September 26, 2024 | by DatapointLabs | views 299
Our presentation, “Beyond Standards: Material Testing and Processing for Successful Simulations of Polymeric Materials (LAW76)”, focuses on the Semi-Analytical Model for Polymers (SAMP), a material law developed for simulating complex polymer behavior in industries like automotive and aerospace. SAMP integrates strain-rate dependencies and a damage model for accurate predictions in crash and impact scenarios but faces limitations like slow convergence and the absence of a damage model that incorporates strain-rate and triaxiality dependencies. We emphasize the need to go beyond standardized testing, advocating for tailored tests that better reflect real-world conditions, such as varying strain rates, geometries, and environmental factors. This presentation also details a semi-automated calibration process for SAMP and BIQUAD models using iterative workflows to optimize simulation accuracy for tension, compression, shear, and impact tests. Ultimately, SAMP’s flexibility and predictive accuracy make it a powerful tool, but its successful implementation requires advanced knowledge, customized testing, and careful calibration to ensure stability and reliability in material simulations.
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Plastics
Yielding/Failure Analysis
Altair RADIOSS
Presentations
Validation
April 17, 2024 | by DatapointLabs | views 1634
Thermoplastic composites present a promising opportunity for innovation within the automotive sector, owing to their lightweight properties, durability, and recyclability. Our efforts concentrate on testing and developing models to accurately simulate the behavior of materials in automotive settings. By delivering precise simulation models, we empower manufacturers to gain deeper insights into the performance of these materials, thereby streamlining their incorporation into vehicle design and manufacturing workflows. This advancement ensures the effective utilization of thermoplastic composites, resulting in tangible advantages such as improved fuel efficiency, enhanced safety, and reduced environmental footprint across the automotive industry.
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Automotive
Nonlinear Material Models
Composites
Validation
May 15, 2023 | by DatapointLabs | views 1579
Simulations play a crucial role in engineering and material science, and their success heavily relies on the accuracy of input data. Material testing, data conversion, fitting, and formatting are essential steps in the simulation process. This conference will highlight the importance of material testing requirements that extend beyond ISO and ASTM standards to obtain reliable data for input into various common material models, such as Elastic-Plastic, Hyperelastic, and Rate Dependent models. The complexity of foam materials is shown through a case study of successful validation of polyurethane (PU) foam ball drop impact test using LAW 90. PU foams exhibit high deformation with rate dependency in compressive loading, as well as viscoelastic unloading behavior. Proper handling of input test data and critical settings in simulation setup are crucial for accurate results. The case study will showcase our streamlined approach to successful simulation of foam materials, including challenges and limitations of current material models.
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Mechanical
Foams
Hyperelastic
Rate Dependency
Altair RADIOSS
Validation
September 22, 2022 | by DatapointLabs | views 1611
Material characterization considerations for SIGMASOFT simulations using thermoplastic and thermoset materials.
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Rheology
Thermal
Mechanical
Plastics
Rubbers
Injection Molding
SIGMASOFT
April 01, 2019 | by DatapointLabs | views 3808
Keynote address delivered at NAFEMS seminar on "Material Properties in Structural Calculation: Modeling, Calibration, Simulation & Optimization."
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Structural Analysis
Presentations
Validation
Materials Information Management
March 13, 2019 | by DatapointLabs | views 4797
Multi-scale material models are being increasing applied for high level simulation of complex materials such as UD layups, fabric laminate composites, fiber-filled plastics. These models require data inputs from a variety of material tests which are then assembled into models used in the finite element solvers. We present an infrastructure for the digitalization of such information, where the required material data are collected including a process for maintaining traceability and consistency of the source data. Information about the compositional characteristics and processing history are captured. Built-in software modules or external client tools can be used for calibration of material models with the resulting material file linked to the source data. The accuracy of the reduced order model can be checked by running a validation simulation against a physical test. Models can be published and released into a master CAE materials library output where they can be used to model such materials for a variety of target solvers. This process improves the reliability and accuracy of composites simulation.
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Aerospace and Defense
Automotive
Structural Analysis
Composites
Presentations
Materials Information Management
October 01, 2018 | by DatapointLabs | views 9037
Multiscale material models are being increasingly applied for high-level simulation of complex materials, such as continuous reinforced material products (unidirectional and woven product forms). These multiscale material models require input data from a minimum of experimental tests, which are then used to characterize a multiscale material model that can be used in structural simulations within a variety of commercial finite element solvers, including OptiStruct, RADIOSS, Abaqus, and LS-Dyna. Using these models, it is possible is to predict the performance of layups from single layer properties, as well as performance of these composites under complex loadings.
We present a framework where the required experimental data are collected, including a process for maintaining traceability and consistency of the experimental data using the Matereality software. Experimental test data are transmitted to the HyperWorks Multiscale Designer software for development of an appropriate multiscale material model. The resulting multiscale material model data is stored within Matereality linked to the source experimental data. Different manufactured layups are tested and compared to simulation in a validation step which provides a measure of the solution accuracy.
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Mechanical
Nonlinear Material Models
Structural Analysis
LS-DYNA
Abaqus
Composites
Altair RADIOSS
Validation
OptiStruct
February 05, 2018 | by DatapointLabs | views 4889
This booklet is intended to be a guide to the V&V process.
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Book Review
Validation
November 01, 2017 | by DatapointLabs | views 3311
Propos recueillis par Olivier Guillon : Pierre-Pascal Bouf représente désormais DatapointLabs en France et plus largement en Europe si nécessaire. Celui-ci nous fait part de l’ambition de l’entreprise spécialiste dans les essais de matériaux et dévoile sa stratégie dont le succès passera inévitablement, selon lui, par une approche de partenariat avec ses clients, en particulier ceux de l’automobile.
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Automotive
Trade Publication
October 07, 2017 | by DatapointLabs | views 5470
Physically accurate simulation is a requirement for initiatives such as late-stage prototyping, additive manufacturing, and digital twinning. Simulations use mathematical models to replicate physical reality. Verification and validation
(V&V) is an important step for high-fidelity simulation. While verification is a way to check the accuracy of these
models, factors such as simulation settings, element type, mesh size, choice of material model, material parameter conversion process, quality and suitability of material property data used can have a large impact on simulation quality. Validation presents a means to check simulation accuracy against a physical experiment.
These validations are a valuable tool to measure solver accuracy prior to use in product development. Confidence is gained that the simulation replicates real-life physical
behavior.
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Presentations
Validation
3D Printing
August 02, 2017 | by DatapointLabs | views 6061
The modeling of material behavior for injection molded plastics is a vital step for good simulation results. We detail the types of material data needed by various injection-molding simulation programs, factors that can affect simulation quality including test techniques and process variables such as moisture content. The case of fiber filled plastics is covered along with the extension to structural analysis applications.
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Plastics
Viscoelastic
Rate Dependency
Injection Molding
Nonlinear Material Models
Structural Analysis
Moldflow
LS-DYNA
Abaqus
Moldex3D
DIGIMAT
SIGMASOFT
Universal Molding
Simpoe-Mold
Presentations
Validation
June 12, 2017 | by DatapointLabs | views 4532
Physically accurate simulation is a requirement for initiatives such as late-stage prototyping, additive manufacturing and digital twinning. The use of mid-stage validation has been shown to be a valuable tool to measure solver accuracy prior to use in simulation. Factors such as simulation settings, element type, mesh size, choice of material model, the material model parameter conversion process, quality and suitability of material property data used can all be evaluated. These validations do not use real-life parts, but instead use carefully designed standardized geometries in a controlled physical test that probes the accuracy of the simulation. With this a priori knowledge, it is possible to make meaningful design decisions. Confidence is gained that the simulation replicates real-life physical behavior. We present three case studies using different solvers and materials, which illustrate the broad applicability of this technique.
...read full post
Mechanical
Plastics
Rubbers
Metals
Structural Analysis
LS-DYNA
Abaqus
ANSYS
Research Papers
Presentations
Validation
3D Printing
April 06, 2017 | by DatapointLabs | views 4950
Performing simulations that can approximate the material behavior of ductile plastics is daunting. Factors such as nonlinear elasticity, inclusion of volumetric and deviatoric behavior, finding and correctly applying the proper material data to create failure criteria are only a few hurdles. A variety of material models exist, each with numerous settings and varied parameter conversion methods. Combined, these cause a great deal of uncertainty for the FEA user. In previous papers, we delved into material models for both LS-DYNA (MAT089, MAT024, and MAT187) and ABAQUS (*ELASTIC, *PLASTIC) using mid-stage validation as a technique to probe solver accuracy. In this presentation, we summarize our findings on the benefits of this combined approach as a general tool to test and tune simulations for greater reliability.
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Mechanical
Plastics
Automotive
High Speed Testing
Nonlinear Material Models
Structural Analysis
Universal Crash
Presentations
Validation
October 21, 2016 | by DatapointLabs | views 6286
Plastics exhibit non-linear viscoelastic behavior followed by a combination of deviatoric and volumetric plastic deformation until failure. Capturing these phenomena correctly in simulation presents a challenge because of limitations in commonly used material models. We follow an approach where we outline the general behavioral phenomena, then prescribe material models for handling different phases of plastics deformation. Edge cases will then be covered to complete the picture. Topics to be addressed include: Using elasto-plasticity; When to use hyperelasticity; Brittle polymers – filled plastics; Failure modes to consider; Criteria for survival; Choosing materials; Spatial non-isotropy from injection molding; Importance of residual stress; Visco-elastic and creep effects; Strain-rate effects for drop test and crash simulations; Fitting material data to FEA material models; The use of mid-stage validation as a tool to confirm the quality of simulation before use in real-life applications.
...read full post
Density
Rheology
Thermal
Mechanical
Plastics
Rubbers
Hyperelastic
Viscoelastic
Plasticity
Rate Dependency
Yielding/Failure Analysis
Injection Molding
Structural Analysis
ANSYS
Presentations
Validation
October 05, 2016 | by DatapointLabs | views 5499
Hyperelastic material models are complex in nature requiring stress-strain properties in uniaxial, biaxial and shear modes. The data need to be self-consistent in order to fit the commonly used material models. Choosing models and fitting this data to these equations adds additional uncertainty to the process. We present a validation mechanism where, using of a standard validation experiment one can compare results from a simulation and a physical test to obtain a quantified measure of simulation quality. Validated models can be used with greater confidence in the design of real-life components.
...read full post
Mechanical
Hyperelastic
Structural Analysis
ANSYS
Papers
Presentations
Validation
October 04, 2016 | by DatapointLabs | views 4887
Finite element analysis of plastics contains assumptions and uncertainties that can affect simulation accuracy. It is useful to quantify these effects prior to using simulation for real-life applications. A mid-stage validation uses a controlled physical test on a standardized part to compare results from simulation to physical experiment. These validations do not use real-life parts but carefully designed geometries that probe the accuracy of the simulation; the geometries themselves can be tested with boundary conditions that can be simulated correctly. In one study, a quasi-static three-point bending experiment of a standardized parallel ribbed plate is performed and simulated, using Abaqus. A comparison of the strain fields resulting from the complex stress state on the face of the ribs obtained by digital image correlation (DIC) vs. simulation is used to quantify the simulation's fidelity. In a second study, a dynamic dart impact experiment is validated using LS-Dyna probing the multi-axial deformation of a polypropylene until failure.
...read full post
Mechanical
Plastics
Automotive
Structural Analysis
LS-DYNA
Abaqus
Presentations
Validation
June 13, 2016 | by DatapointLabs | views 5711
Quantifying simulation accuracy before running crash simulations could be a helpful confidence building measure. This study continues our development of a mechanism to validate material models for plastics used in modeling high-speed impact. Focusing on models for isotropic materials that include options for rate dependency and failure, we explore other models commonly used for ductile plastics including MAT089 and MAT187.
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Mechanical
Plastics
Rate Dependency
Yielding/Failure Analysis
Automotive
Toys/Sporting Goods
Packaging
High Speed Testing
LS-DYNA
Research Papers
Validation
June 07, 2016 | by DatapointLabs | views 5726
With the advent of 3D printing and additive manufacturing, manufacturing designs previously thought difficult to produce can now be generated quickly and efficiently and without tooling. In the aerospace industry, weight is often tied directly to cost and is thus of great importance to any engineering design. Traditionally, the design process often involves much iteration between the designer and the analyst, where the designer submits a design to the analyst, and then the analyst completes his or her analysis and sends recommendations back to the designer. The process is repeated until a valid design meets the analysis criteria. The design is then handed to the manufacturing team which then may have additional constraints or concerns and iterations can continue. Additive manufacturing coupled with topology optimization allows the design and analysis loops and manufacturing iterations to be reduced significantly or even eliminated. The critical step is to ensure that the part will perform as simulated.
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Metals
Aerospace and Defense
Structural Analysis
Altair RADIOSS
Research Papers
Validation
3D Printing
June 03, 2016 | by DatapointLabs | views 8085
This book is intended to be a companion to the NAFEMS book, "An Introduction to the Use of Material Models in FE". It informs Finite Element Analysis users of the manner and methodologies by which materials are tested in order to calibrate material models currently implemented in various FEA programs. While the authors seek first to satisfy the basic material models outlined in the companion book, they make important extensions to FEA used in currently active areas including explicit simulation.
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Mechanical
Plastics
Rubbers
Foams
Metals
Hyperelastic
Viscoelastic
Plasticity
Rate Dependency
Yielding/Failure Analysis
Aerospace and Defense
Automotive
Biomedical
Building Materials
Consumer Products
Energy and Petroleum
Material Supplier
Furniture
Industrial Goods
CAE Vendor/Supplier
Packaging
Home Appliances
Research Laboratory
High Speed Testing
Nonlinear Material Models
Structural Analysis
LS-DYNA
Abaqus
ANSYS
DIGIMAT
SOLIDWORKS
MSC.DYTRAN
MSC.MARC
MSC.NASTRAN
NX Nastran
PAM-COMFORT
PAM-CRASH
Altair RADIOSS
SIMULIA
Book Review
May 24, 2016 | by DatapointLabs | views 5893
Simulations contain assumptions and uncertainties that a designer must evaluate to obtain a measure of accuracy. The assumptions of the product design can be differentiated from the ones for the solver and material model through the use of a mid-stage validation. An open loop validation uses a controlled test on a standardized part to compare results from a simulation to the physical experiment. From the validation, confidence in the material model and solver is gained. In this study, the material properties of a polypropylene are tested to characterize for an *ELASTIC *PLASTIC model in ABAQUS. A validation of a quasi-static three-point bending experiment of a parallel ribbed plate is then performed and simulated. A comparison of the strain fields resulting from the complex stress state on the face of the ribs obtained by digital image correlation (DIC) vs. simulation is used to quantify the simulation's fidelity.
...read full post
Plastics
Plasticity
Automotive
Biomedical
Consumer Products
Material Supplier
Toys/Sporting Goods
Furniture
Packaging
Home Appliances
Nonlinear Material Models
Structural Analysis
Abaqus
Research Papers
Validation
September 23, 2015 | by DatapointLabs | views 4438
Thermoplastic materials are one of the largest categories of materials to be injection molded. Moisture-sensitive materials can lead to issues in the molding process. Simulation of the injection molding process requires sophisticated and exact material properties to be measured. This presentation discusses the testing required to characterize a thermoplastic material for use in SIGMASOFT, as well as the effects of moisture on viscosity measurement of a moisture-sensitive material. Consequences of basing designs on wet or dry materials are covered. Implementation of material data into the software to produce a successful injection molding simulation simulation is described.
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Rheology
Plastics
CAE Vendor/Supplier
Injection Molding
Nonlinear Material Models
SIGMASOFT
Presentations
September 10, 2015 | by DatapointLabs | views 4487
Molding Views, brought to you by the Injection Molding Division of the Society of Plastics Engineers
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Rheology
Mechanical
Injection Molding
Moldflow
Moldex3D
SIGMASOFT
Universal Molding
Simpoe-Mold
Newsletters
June 11, 2015 | by DatapointLabs | views 5355
With the growing interest in 3D printing, there is a desire to accurately simulate the behavior of components made by this process. The layer by layer print process appears to create a morphology that is different from that from conventional manufacturing processes. This can have dramatic impact on the material properties, which in turn, can affect how the material is modeled in simulation. In the first stage of our work, we seek to test an additively manufactured material for mechanical properties and validate its use in ANSYS simulation using the Cornell Bike Crank model.
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Mechanical
ANSYS
Research Papers
Validation
3D Printing
April 28, 2015 | by DatapointLabs | views 5086
There is interest in quantifying the accuracy of different material models being used in LS-DYNA today for the modeling of plastics. In our study, we characterize two ductile, yet different materials, ABS and polypropylene for rate dependent tensile properties and use the data to develop material parameters for the material models commonly used for plastics: MAT_024 and its variants, MAT_089 and MAT_187. We then perform a falling dart impact test which produces a complex multi-axial stress state and simulate this experiment using LS-DYNA. For each material model we are able to compare simulation to actual experiment thereby obtaining a measure of fidelity of the simulation to reality. In this way, we can assess the benefits of using a particular material model for plastics simulation.
...read full post
Mechanical
Plastics
Rate Dependency
LS-DYNA
Research Papers
Validation
March 12, 2015 | by DatapointLabs | views 5646
Finite-element analysis and injection-molding simulation are two technologies that are seeing widespread use today in the design of plastic components. Limitations exist in our ability to mathematically describe the complexity of polymer behavior to these software packages. Material models commonly used in finite-element analysis were not designed for plastics, making it difficult to correctly describe non-linear behavior and plasticity of these complex materials. Time-based viscoelastic phenomena further complicate analysis. Dealing with fiber fillers brings yet another layer of complexity. It is vital to the plastics engineer to comprehend these gaps in order to make good design decisions. Approaches to understanding and dealing with these challenges, including practical strategies for everyday use, will be discussed.
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Mechanical
Plastics
Blow Molding
Extrusion
Injection Molding
Nonlinear Material Models
Structural Analysis
Thermoforming
LS-DYNA
Abaqus
DIGIMAT
Presentations
November 21, 2014 | by DatapointLabs | views 4656
Thermoplastic materials are one of the largest categories of materials to be injection molded. Simulation of the injection molding process requires sophisticated and exact material properties to be measured. This presentation will discuss the testing required to characterize a material for use in SIGMASOFT, as well as the significance of material model parameters. Differences in testing methodology for amorphous and semi-crystalline polymers will be covered, along with step-by-step implementation into the software to produce a successful injection molding simulation simulation.
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Plastics
Electonics/Electrical
Injection Molding
Nonlinear Material Models
Structural Analysis
SIGMASOFT
Presentations
October 28, 2014 | by DatapointLabs | views 4861
It has long been desired to quantify the accuracy of simulation results. Through developments in digital image correlation (DIC) techniques, it is now possible to quantify the deviation between simulation and real life experimentation. In this paper, three-dimension DIC measurements of deformed parts are compared to deformed surfaces predicted in simulation. Using DIC, it is possible to import deformed surface elements from simulation and map the magnitude of deviation from the measurements of the actual deformed shape.
...read full post
High Speed Testing
Nonlinear Material Models
Structural Analysis
ANSYS
Presentations
Validation
October 08, 2014 | by DatapointLabs | views 4526
LS-DYNA software contains a wealth of material models that allow for the simulation of transient phenomena. The Matereality® CAE Modeler is a generalized pre-processor software used to convert material property data into material parameters for different material models used in CAE. In a continuation of previously presented work, we discuss the extension of the CAE Modeler software to commonly used material models beyond MAT_024. Software enhancements include advanced point picking to perform extrapolations beyond the tested data, as well as the ability to fine-tune the material models while scrutinizing the trends shown in the underlying raw data. Advanced modeling features include the ability to tune the rate dependency as well as the initial response. Additional material models that are quite complex and difficult to calibrate are supported, including those for hyperelastic and viscoelastic behavior. As before, the written material cards are directly readable into the LS-DYNA software, but now they can also be stored and catalogued in a material card library for later reuse.
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Plastics
Rubbers
Foams
Metals
High Speed Testing
Injection Molding
Nonlinear Material Models
Structural Analysis
LS-DYNA
Composites
Presentations
September 21, 2014 | by DatapointLabs | views 4308
Plastics exhibit non-linear viscoelastic behavior followed by a combination of deviatoric and volumetric plastic deformation until failure. Capturing these phenomena correctly in simulation presents a challenge because of the inadequacy of currently used material models. We follow an approach where we outline the general behavioral phenomena, then prescribe material models for handling different phases of plastics deformation. Edge cases will then be covered to complete the picture. Topics to be addressed include: Using elasto-plasticity; When to use hyperelasticity; Brittle polymers – filled plastics; Failure modes to consider; Criteria for survival; Choosing materials; Spatial non-isotropy from injection molding; Importance of residual stress; Visco-elastic and creep effects; Strain-rate effects for drop test and crash simulations; Fitting material data to FEA material models.
...read full post
Plastics
High Speed Testing
Nonlinear Material Models
ANSYS
Presentations
August 12, 2014 | by DatapointLabs | views 5369
Material specifications define properties for incoming materials to meet required criteria. We present software that manages creation of material specifications, input of properties and material composition; and provides a way to evaluate qualification per specification. While it is designed for OEM/Tier n environments, it is also applicable for materials suppliers.
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Automotive
Moldflow
LS-DYNA
Abaqus
ANSYS
Moldex3D
DIGIMAT
SIGMASOFT
SOLIDWORKS
ADINA
ANSYS FIDAP
B-Sim
Cadmould
Altair HyperXtrude
MSC.DYTRAN
MSC.MARC
MSC.NASTRAN
Universal Molding
NX Nastran
PAM-CRASH
PAM-FORM
PlanetsX
Polycad
POLYFLOW Blow Molding
POLYFLOW Extrusion
POLYFLOW Thermoforming
PolyXtrue
Altair RADIOSS
Simpoe-Mold
T-Sim
VEL
VISI Flow
WinTXS
Presentations
May 13, 2014 | by DatapointLabs | views 5203
Plastics appeared as design materials of choice about 30 years ago. They brought with them huge design challenges because their multi-variable, non-linear nature was not well understood by engineers trained to work in a linear elastic world. We outline a 20 year journey accompanying our customers in their efforts to understand and simulate these remarkable materials to produce the highly reliable plastic products of today. We discuss challenges related to processes such as injection molding vs. blow-molding; coping with filled plastics; the difficulties of modeling polymers for crash applications. We include our latest findings related to volumetric yield in polymers and its relationship to failure. We describe the material database technology that was created to store this kind of multi-variable data and the analytical tools created to help the CAE engineer understand and use plastics material data.
...read full post
Plastics
Automotive
Blow Molding
High Speed Testing
Injection Molding
Nonlinear Material Models
Structural Analysis
Moldflow
LS-DYNA
Abaqus
ANSYS
Moldex3D
DIGIMAT
Universal Crash
Universal Molding
Universal Structural
PAM-CRASH
Presentations
April 30, 2014 | by DatapointLabs | views 4313
The use of CAE in design decision-making has created a need for proven simulation accuracy. The two areas where simulation touches the ground are with material data and experimental verification and validation (V&V). Precise, well designed and quantitative experiments are key to ensure that the simulation initiates with correct material behavior. Similar validation experiments are needed to verify simulation and manage the risk associated with this predictive technology.
...read full post
Plastics
Rubbers
Foams
Metals
Automotive
Biomedical
Building Materials
Consumer Products
Energy and Petroleum
Material Supplier
Toys/Sporting Goods
Electonics/Electrical
Industrial Goods
CAE Vendor/Supplier
Mold Maker/Designer
Nonlinear Material Models
Structural Analysis
Abaqus
Composites
SIMULIA
Presentations
February 13, 2014 | by DatapointLabs | views 4396
As part of Cornell University's mechanical engineering curriculum and study of classical beam theory, an aluminium beam is deformed to a specific load. Theoretical strains are calculated at certain points along the beam using beam theory, and then verified by using strain gauges placed at these points on the beam. This experiment is then extended to simulation of the same test setup in simulation software, where strains are analyzed at the same points. Discrepancies between the simulation, theory, and strain gauge results have often plagued the test, especially when incorporating more complex beam design. Through use of digital image correlation (DIC) it is possible to pinpoint some of the problem areas in the beam analysis and provide a better understanding of the localized strains that occur at any point in the deformed beam. The use of DIC provides a full field validation of simulation data, rather than a single spot check that strain gauges can provide. This validation technique helps to eliminate error that is associated with strain gauge placement and the possibility of missing strain hot spots that can arise when analyzing complex deformations or geometries.
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Plastics
Metals
Aerospace and Defense
Automotive
Biomedical
Building Materials
Consumer Products
Material Supplier
Toys/Sporting Goods
Electonics/Electrical
Industrial Goods
CAE Vendor/Supplier
Mold Maker/Designer
Structural Analysis
ANSYS
Presentations
October 29, 2013 | by DatapointLabs | views 4478
There is interest in quantifying the differences between simulation and real life experimentation. This kind of work establishes a baseline for more complex simulations bringing a notion of traceability to the practice of CAE. We present the use of digital image correlation as a way to capture strain fields from component testing and compare these to simulation. Factors that are important in ensuring fidelity between simulation and experiment will be discussed.
...read full post
Plastics
Aerospace and Defense
Automotive
Biomedical
Material Supplier
Electonics/Electrical
CAE Vendor/Supplier
Nonlinear Material Models
Structural Analysis
Abaqus
Composites
SIMULIA
Presentations
September 15, 2013 | by DatapointLabs | views 4329
The development of material parameters for FEA is heavily reliant on precision material data that captures the stress-strain relationship with fidelity. While conventional methods involving UTMs and extensometers are quite adequate for obtaining such data on a number of materials, there are important cases where they have been known to be inadequate. The testing of composites to obtain directional properties remains a complex task because of the difficulty related to measuring these properties in different orientations. Digital Image Correlation (DIC) methods are able to capture the stress-strain relationship all the way to failure. In this paper, we combine DIC and conventional methods to measure directional properties of composites. We exploit the unique capability of DIC to retroactively place virtual strain gauges in areas of critical interest in the test specimen. Utilising an Iosipescu fixture, we measure shear properties of structured composites in a variety of orientations to compute the parameters of an orthotropic linear elastic material model. Model consistency is checked by validation using Abaqus.
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Aerospace and Defense
Nonlinear Material Models
Structural Analysis
Abaqus
Composites
SIMULIA
Research Papers
April 07, 2013 | by DatapointLabs | views 4316
Today, CAE is integrated with modern automotive product development. This creates new challenges for departments that support new product development. In the materials arena, the testing is elevated to much higher levels of sophistication and precision to accommodate the complex material models used in CAE. It is no longer simple matter to convert raw data into material model parameters. We present an end-to-end strategy that gives automakers a well managed pathway to transforming to simulation-based design. We operate a quick-turnaround expert material testing lab to support high-end CAE and product development. We provide a data management software designed specifically to capture and display material data of any complexity. The software can transform raw material data into material parameter files for most commonly used simulations. The CAE Modeler software is of adequate sophistication to fit equations to data, visualize material models along with raw data, and output material cards. Examples for high strain-rate crash material modeling will be presented.
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Automotive
CAE Vendor/Supplier
Nonlinear Material Models
Structural Analysis
Presentations
March 10, 2013 | by DatapointLabs | views 4287
SAMP-1 is a complex material model designed to capture non-Mises yield and localization behavior in plastics. To perform well, it is highly dependent on accurate post-yield material data. A number of assumptions and approximations are currently used to translate measured stress-strain data into the material parameters related to these inputs. In this paper, we look at the use of direct localized strain measurements using digital image correlation (DIC) as a way to more directly extract the required data needed for SAMP-1.
...read full post
Plastics
Nonlinear Material Models
Structural Analysis
LS-DYNA
Composites
Research Papers
May 08, 2011 | by DatapointLabs | views 4642
DatapointLabs' TestPaks (material testing + model calibration + Abaqus input decks) for rate-dependent, hyperelastic, viscoelastic, NVH, and the use of Abaqus CAE Modeler to transform raw data into material cards will be presented. A representative from Idiada will present a case study explaining the use of DatapointLabs’ material data and TestPaks for simulation.
...read full post
Plastics
Rubbers
Foams
Metals
High Speed Testing
Nonlinear Material Models
Structural Analysis
Abaqus
Composites
SIMULIA
Presentations
March 10, 2011 | by DatapointLabs | views 4325
The testing of materials for use in crash and safety simulations and the conversion of test data into material models is a process that is not well standardized in the industry. Consequently, CAE users face uncertainty and risk in this process that can have a negative impact on simulation quality. In this workshop, we present approaches currently used in the US for the gathering of high quality test data plus the acclaimed Matereality CAE Modeler software that is used to transform high strain-rate data into crash material cards.
...read full post
Automotive
High Speed Testing
Nonlinear Material Models
Structural Analysis
LS-DYNA
Abaqus
ANSYS
DIGIMAT
SIGMASOFT
NX Nastran
PAM-CRASH
Altair RADIOSS
Presentations
January 19, 2011 | by DatapointLabs | views 4032
We present a methodology for DIGIMAT users to perform the DIGIMAT MX reverse engineering process to obtain material parameter inputs for crash, elasto-plastic, creep and visco-elasticity. The injection-molding process used involves a standardized plaque geometry with fully developed flow, with test specimens taken from a specific plaque location. A standardized testing procedure is applied and the resulting DIGIMAT MX inputs are handled in a streamlined data stream, which saves time and improves the reliability of the reverse engineering process. The DIGIMAT MX reverse engineering itself can be performed as a service in collaboration with e-Xstream. This gives the user a speedy and tightly controlled process for performing complex finite element analysis with filled plastics
...read full post
Blow Molding
Extrusion
High Speed Testing
Injection Molding
Nonlinear Material Models
Structural Analysis
DIGIMAT
Presentations
August 03, 2010 | by DatapointLabs | views 4547
Ultra-high molecular weight polyethylene (UHMWPE) is used extensively in orthopedic applications within the human body. Components made from these materials are subject to complex loading over extended periods of time. Modeling of components used in such applications depends heavily on having material data under in-vivo conditions. We present mechanical and visco-elastic properties measured in saline at 37C. Comparisons to conventionally measured properties at room temperature are made.
...read full post
Plastics
Biomedical
Blow Molding
Extrusion
Injection Molding
Nonlinear Material Models
Structural Analysis
Moldflow
Abaqus
ANSYS
SIGMASOFT
Papers
POLYFLOW Blow Molding
POLYFLOW Extrusion
POLYFLOW Thermoforming
July 21, 2010 | by DatapointLabs | views 4415
The limitations of modeling materials for simulation are discussed, including lack of clarity in material model requirements, gaps between the material data and the model to which it will be fitted, issues in obtaining pertinent properties, difficulties in parameter conversion (fitting), and preparation of input files for the software being used. Means to address these limitations are presented, including understanding the model completely, measuring the correct data with precision on the right material, selecting the best model for the data and ensuring the best fit of the model to the data, validating the model against a simple experiment, and following best practices to create an error-free input file.
...read full post
Plastics
Rubbers
Foams
Aerospace and Defense
Automotive
Biomedical
Consumer Products
Material Supplier
Toys/Sporting Goods
Electonics/Electrical
Industrial Goods
Packaging
Home Appliances
Presentations
May 28, 2010 | by DatapointLabs | views 4203
Material modeling has become increasing important as ANSYS software has added analysis capabilities such as non-linear CAE, crash, CFD, and manufacturing process simulation. Poor material representaion brings risk to CAE and product development. Material data needs for various material models are discussed.
...read full post
ANSYS
ANSYS FIDAP
MSC.NASTRAN
Presentations
May 26, 2010 | by DatapointLabs | views 4146
Many material models are available for crash simulation. However, common models are not designed for plastics. We present best practices developed for adapting common models to plastics, as well as best testing protocols to generate clean, accurate rate-dependent data. In addition, we present a streamlined process to convert raw data to LS-DYNA material cards, and harmonized material datasets that allow the same raw data to be used for other crash and rate-dependent analysis software.
...read full post
Plastics
Automotive
High Speed Testing
Nonlinear Material Models
Structural Analysis
LS-DYNA
Abaqus
ANSYS
PAM-CRASH
Altair RADIOSS
Presentations
April 14, 2010 | by DatapointLabs | views 4044
Material testing for simulation is about understanding how to best describe a material’s behavior as input for the CAE code. Such testing requires expertise and experience beyond testing performed in a typical test laboratory; while the test instruments may be the same, the knowledge of CAE and experience with diverse materials is increasingly important. FEA software such as ANSYS is being increasingly used for non-linear simulations. We discuss how DatapointLabs' uncommon material expertise helps you avoid problems when the data is being generated these applications.
...read full post
Research Papers
June 12, 2009 | by DatapointLabs | views 4449
Over the past couple of decades, standard test methods and material models have existed for rubber-like materials. These materials were classified under the category of Hyperelastic materials. Well established physical test methods and computational procedures exist for the characterization of the material behavior in tension, compression, shear volumetric response, tear strength etc. However, effective modeling of the fracture behavior of hyperelastic materials using finite element techniques is very challenging. In this paper, we make an attempt to demonstrate the use of such standard test methods and the applicability of such test data for performing finite element analyses of complex nonlinear problems using Abaqus. Our goal is to demonstrate the effective use of standard physical test data to model multi-axial loading situations and fracture of hyperelastic materials through tear tests and indentation test simulations.
...read full post
Rubbers
Material Supplier
Industrial Goods
Nonlinear Material Models
Structural Analysis
Abaqus
Research Papers
May 11, 2009 | by DatapointLabs | views 5408
High strain rate material modelling of polymers for use in crash and drop testing has been plagued by a number of problems. These include poor quality and noisy data, material models unsuited to polymer behaviour and unclear material model calibration guidelines. The modelling of polymers is thus a risky proposition with a highly variable success rate. In previous work, we tackled each of the above problems individually. In this paper, we summarize and then proceed to present a material modelling strategy that can be applied for a wide variety of polymers.
...read full post
Mechanical
Plastics
Aerospace and Defense
Automotive
Consumer Products
Material Supplier
Industrial Goods
Packaging
Home Appliances
High Speed Testing
Nonlinear Material Models
Structural Analysis
LS-DYNA
Abaqus
ANSYS
MSC.DYTRAN
PAM-CRASH
Altair RADIOSS
Research Papers
April 13, 2009 | by DatapointLabs | views 4591
We seek to lay down a framework to help us understand the different behavioral classes of foams. Following a methodology that we previously applied to plastics, we will then attempt to propose the right LS-DYNA material models that best capture these behaviours. Guidelines for model selection will be presented as well as best practices for characterization. Limitations of existing material models will be discussed.
...read full post
Foams
Automotive
Consumer Products
Material Supplier
Packaging
Home Appliances
High Speed Testing
Nonlinear Material Models
Structural Analysis
LS-DYNA
Abaqus
ANSYS
MSC.DYTRAN
Research Papers
February 18, 2009 | by DatapointLabs | views 4308
Abaqus’ Non-linear NVH capability permits the capture of material behavior of rubber seals and bushings, plastic parts and foam inserts which have a significant influence on the simulation. In this presentation, we discuss material calibration procedures for this application.
...read full post
Plastics
Rubbers
Automotive
Building Materials
Material Supplier
Nonlinear Material Models
Structural Analysis
Abaqus
Presentations
July 17, 2008 | by DatapointLabs | views 4278
If you want a crash simulation involving plastics to yield useful results, it is important to model the material behavior appropriately. The high strain rates have a significant effect on the properties, and failure can be ductile or brittle in nature, depending on a number of factors.
...read full post
Plastics
Aerospace and Defense
Automotive
Biomedical
Consumer Products
Material Supplier
Toys/Sporting Goods
Industrial Goods
Packaging
High Speed Testing
Nonlinear Material Models
Structural Analysis
LS-DYNA
Abaqus
ANSYS
MSC.DYTRAN
PAM-CRASH
Altair RADIOSS
Research Papers
May 16, 2008 | by DatapointLabs | views 4697
We present a perspective on material modeling as applied to mold analysis requirements. Melt-solid transitions and the case for a unified material model are discussed, along with prediction of post-filling material behavior and shrinkage, and the impact of viscous heating on flow behavior and material degradation.
...read full post
Plastics
Rubbers
Foams
Metals
Aerospace and Defense
Automotive
Biomedical
Consumer Products
Energy and Petroleum
Electonics/Electrical
Industrial Goods
CAE Vendor/Supplier
Packaging
Home Appliances
Blow Molding
Extrusion
Injection Molding
Nonlinear Material Models
Moldflow
Composites
Presentations
Gels
Oils/Lubricants
Waxes
November 27, 2007 | by DatapointLabs | views 4719
Many LS-DYNA models are used for plastics crash simulation. However, common models are not designed for plastics. We present best practices developed for adapting common models to plastics, as well as best testing protocols to generate clean, accurate rate-dependent data.
...read full post
Metals
Aerospace and Defense
Automotive
Consumer Products
Material Supplier
Industrial Goods
Packaging
High Speed Testing
Nonlinear Material Models
Structural Analysis
LS-DYNA
Abaqus
ANSYS
MSC.DYTRAN
PAM-CRASH
Presentations
November 15, 2006 | by DatapointLabs | views 4690
A considerable amount of CAE today is devoted to the simulation of non-metallic materials, many of which exhibit non-linear behavior. However, most material models to date are still based on metals theory. This places severe restrictions on the proper description of their behavior in CAE. In this paper, we describe non-linear elastic behavior and its interrelationship with plastic behavior in plastics. Special attention is given to the differentiation between visco-elastic (recoverable) strain and plastic (non-recoverable) strain. The goal of this work is to have a material model for plastics that can describe both loading and unloading behavior accurately and provide an accurate measure of damage accumulation during complex loading operations.
...read full post
Plastics
Rubbers
Aerospace and Defense
Automotive
Biomedical
Consumer Products
Material Supplier
Toys/Sporting Goods
Packaging
Home Appliances
Nonlinear Material Models
Structural Analysis
Abaqus
Research Papers
September 21, 2006 | by DatapointLabs | views 4590
The volume of plastics that are subjected to impact simulation has grown rapidly. In a previous paper, we discussed why different material models are needed to describe the highly varied behavior exhibited by these materials. In this paper, we cover the subject in more detail, exploring in depth, the nuances of commonly used LS-DYNA material models for plastics, covering important exceptions and criteria related to their use.
...read full post
Plastics
Aerospace and Defense
Automotive
Consumer Products
Material Supplier
Industrial Goods
Packaging
Nonlinear Material Models
Structural Analysis
LS-DYNA
Abaqus
ANSYS
PAM-CRASH
Altair RADIOSS
Research Papers
May 19, 2006 | by DatapointLabs | views 4234
The volume of plastics that are subjected to impact simulation has grown rapidly. In a
previous paper, we discussed why different material models are needed to describe the
highly varied behavior exhibited by these materials. In this paper, we cover the subject
in more detail, exploring in depth, the nuances of commonly used LS-DYNA material
models for plastics, covering important exceptions and criteria related to their use.
...read full post
Plastics
High Speed Testing
LS-DYNA
Research Papers
April 28, 2005 | by DatapointLabs | views 4988
High strain-rate properties have many applications in the simulation of automotive crash and product drop testing.
These properties are difficult to measure. These difficulties result from inaccuracies in extensometry at high strain
rates due to extensometer slippage and background noise due to the sudden increase in stress at the start of the
test. To eliminate these inaccuracies we use an inferential technique that correlates strain to extension at low
strain rates and show that this can be extended to measure strain at higher strain rates
...read full post
Mechanical
Plastics
Rate Dependency
Aerospace and Defense
Automotive
Consumer Products
Material Supplier
Toys/Sporting Goods
Packaging
Home Appliances
High Speed Testing
Nonlinear Material Models
Structural Analysis
LS-DYNA
Abaqus
ANSYS
MSC.DYTRAN
PAM-CRASH
Research Papers
July 15, 2003 | by DatapointLabs | views 4500
Assurance of quality in raw materials, control over production, and a basic understanding of criteria for performance all require a sure and complete
knowledge of analytical methods for plastics. The present volume organizes the vast world of plastics analysis into a relatively compact form. A plastics engineer will find familiar territory in such subjects as
rheometry, differential scanning calorimetry, and measurement of thermal properties. Polymer physicists and chemists will be at home with spectroscopic analyses, liquid chromatography, and nuclear magnetic resonance. All these topics and many more are covered in twelve chapters written by an impressive array of experts drawn from industry and academia.
...read full post
Rheology
Thermal
Plastics
Structural Analysis
Book Review
April 23, 2003 | by DatapointLabs | views 4221
This book covers some of the most significant techniques used in modern analytical technology to characterize plastic and composite materials.
...read full post
Plastics
Rubbers
Foams
Composites
November 09, 2002 | by DatapointLabs | views 4031
There has been a long standing need for a book that describes the
process of injection molding using the insights developed from twenty years of computer aided engineering (CAE). The authors, all veterans of injection molding CAE, have filled this need with their book. "Successful
Injection Molding" is a lot more than a book about injection molding CAE. It is clear at this stage that CAE is a tool, which, if well handled, can provide excellent results. That being said, a successful implementer of CAE for injection molding must have a range of insights into the diverse
idiosyncrasies of this enormously complex manufacturing process. The book is successful in clearly addressing these issues.
...read full post
Injection Molding
Book Review
March 13, 2001 | by DatapointLabs | views 4569
Hyperelastic models are used extensively in the finite element analysis of rubber and elastomers. These models need to be able to describe elastomeric behavior at large deformations and under different modes of deformation. In order to accomplish this daunting task, material models have been presented that can mathematically describe this behavior [1]. There are several in common use today, notably, the Mooney-Rivlin, Ogden and Arruda Boyce. Each of these has advantages that we will discuss in this article. Further, we will examine the applicability of a particular material model for a given modeling situation.
...read full post
Rubbers
Foams
Aerospace and Defense
Automotive
Biomedical
Nonlinear Material Models
Structural Analysis
Abaqus
ANSYS
SOLIDWORKS
MSC.MARC
NX Nastran
Research Papers
September 13, 2000 | by DatapointLabs | views 4264
We discuss open issues in material models for plastics and propose better means of acquiring the right material data for Moldflow simulations using current testing technologies.
...read full post
Plastics
Material Supplier
Mold Maker/Designer
Injection Molding
Moldflow
Presentations
March 16, 1999 | by DatapointLabs | views 4593
We discuss developments in viscosity modeling. New models are not generalized, but are designed to predict expected trends for polymers and incorporate both Newtonian and shear-thinning behavior.
...read full post
Plastics
Material Supplier
Mold Maker/Designer
Injection Molding
Moldflow
Presentations
July 14, 1998 | by DatapointLabs | views 4320
We discuss material properties in injection molding simulations, including the definition of property requirements, identification of evaluation parameters, and the role of material properties at each stage of the injection molding process, from mold filling through cooling, post-filling and shrinkage/warpage considerations.
...read full post
Plastics
Material Supplier
Mold Maker/Designer
Packaging
Injection Molding
Moldflow
Moldex3D
Cadmould
C-MOLD
Presentations
October 22, 1997 | by DatapointLabs | views 4938
With the recent changes in the crashworthiness requirements for US automobiles for improved safety, design engineers are being challenged to design interior trim systems comprised of polymeric materials to meet these new impact requirements. Impact analysis programs are being used increasingly by designers to gain an insight into the final part performance during the design stage. Material models play a crucial role in these design simulations by representing the response of the material to an applied stimulus. In this work, we seek to develop novel test methods to generate high speed stress-strain properties of plastics, which can be used as input to structural analysis programs...
...read full post
Plastics
Metals
Aerospace and Defense
Material Supplier
Toys/Sporting Goods
Packaging
Home Appliances
High Speed Testing
Nonlinear Material Models
Structural Analysis
Thermoforming
LS-DYNA
Abaqus
ANSYS
MSC.DYTRAN
PAM-CRASH
Research Papers
August 14, 1997 | by DatapointLabs | views 4102
This book presents a concise and easily readable introduction to polymer behavior for design and production engineers. It seeks to explain the behavior of plastics and rubber using a materials science framework, by relating observed phenomena to changes in morphological and molecular structure. This presents a powerful way for engineers to grasp the underlying factors that make polymers the complex materials that they are. The reader is encouraged to step away from using linear-elastic metals concepts when designing with plastics. The pitfalls of such
simplifications are pointed out and guidelines are presented to aid the designer in adopting a non-linear approach.
...read full post
Plastics
Rubbers
Nonlinear Material Models
Book Review
April 15, 1994 | by DatapointLabs | views 4086
Two approaches to polymer processing rheology are discernible; by theoreticians. who are concerned with a fundamental description of what would be happening if certain idealized criteria are met; and by practitioners, who are concerned with the results of what is actually happening.” In his newly revised book, Mr. Cogswell skillfully treads the middle ground between these camps, providing an interesting, informative guide to rheology for the design engineer.
...read full post
Rheology
Industrial Goods
Book Review
March 18, 1994 | by DatapointLabs | views 4176
This book presents a valuable resource for engineers and designers seeking to apply structural analysis and other advanced methods to the design of plastic parts. The reader learns what to expect for the mechanical properties of polymers and develops a grasp of how plastics respond to various applied stress conditions. The book introduces mechanical tests and polymer transitions, moving onward into chapters on elastic behavior, creep and stress relaxation, dynamic mechanical properties, stress- strain behavior and strength, It also covers abrasion, fatigue, friction and stress cracking. Additionally, the effects of fillers and fibers on these properties are considered.
...read full post
Mechanical
Plastics
Structural Analysis
Composites
Book Review
January 17, 1994 | by DatapointLabs | views 4167
This book, edited by the Wisconsin based team of Osswald, Turng and Gramman, represents a compilation of work by several well known authors and brings together a body of knowledge that will be appreciated by injection molding professionals and students of plastics processing.
...read full post
Plastics
Injection Molding
Book Review
July 14, 1993 | by DatapointLabs | views 4725
The primary purpose of this book is to describe the application of modern engineering analysis techniques to the design of components fabricated from thermoplastic materials. The book, the first of its kind to address the unique behavioral characteristics of thermoplastics and their impact on finite element analysis (FEA), points out the need for plastics designers to move on to nonlinear analysis in order to truly simulate the behavior of plastic parts. According to the authors, the easy availability of high speed computing and efficient analysis codes means that it is no longer necessary nor cost-effective to restrict oneself to simple linear analyses.
...read full post
Plastics
Nonlinear Material Models
Structural Analysis
Thermoforming
Book Review
"RenoBrico"
Finite-element analysis and injection-molding simulation are two technologies that are seeing widespread use today in the design of plastic components. Limitations exist in our ability to mathematically describe the complexity of polymer behavior to these software packages. Material models commonly used in finite-element analysis were not designed for plastics, making it difficult to correctly describe non-linear behavior and plasticity of these complex materials. Time-based viscoelastic phenomena further complicate analysis. Dealing with fiber fillers brings yet another layer of complexity. It is vital to the plastics engineer to comprehend these gaps in order to make good design decisions. Approaches to understanding and dealing with these challenges, including practical strategies for everyday use, will be discussed.
...click to view
"A Novel Technique to Measure Tensile Properties of Plastics at High Strain Rates"
High strain-rate properties have many applications in the simulation of automotive crash and product drop testing.
These properties are difficult to measure. These difficulties result from inaccuracies in extensometry at high strain
rates due to extensometer slippage and background noise due to the sudden increase in stress at the start of the
test. To eliminate these inaccuracies we use an inferential technique that correlates strain to extension at low
strain rates and show that this can be extended to measure strain at higher strain rates ...click to view
"Thermoplastic Material Testing for Use in SIGMASOFT"
Thermoplastic materials are one of the largest categories of materials to be injection molded. Simulation of the injection molding process requires sophisticated and exact material properties to be measured. This presentation will discuss the testing required to characterize a material for use in SIGMASOFT, as well as the significance of material model parameters. Differences in testing methodology for amorphous and semi-crystalline polymers will be covered, along with step-by-step implementation into the software to produce a successful injection molding simulation simulation.
...click to view
"A Robust Methodology to Calibrate Crash Material Models for Polymers"
High strain rate material modelling of polymers for use in crash and drop testing has been plagued by a number of problems. These include poor quality and noisy data, material models unsuited to polymer behaviour and unclear material model calibration guidelines. The modelling of polymers is thus a risky proposition with a highly variable success rate. In previous work, we tackled each of the above problems individually. In this paper, we summarize and then proceed to present a material modelling strategy that can be applied for a wide variety of polymers. ...click to view
"Methodology for Selection of Material Models for Plastics Impact Simulation. "
The volume of plastics that are subjected to impact simulation has grown rapidly. In a
previous paper, we discussed why different material models are needed to describe the
highly varied behavior exhibited by these materials. In this paper, we cover the subject
in more detail, exploring in depth, the nuances of commonly used LS-DYNA material
models for plastics, covering important exceptions and criteria related to their use. ...click to view
"Understanding the Role of Material Properties in Simulations, Part 2"
We discuss material properties in injection molding simulations, including the definition of property requirements, identification of evaluation parameters, and the role of material properties at each stage of the injection molding process, from mold filling through cooling, post-filling and shrinkage/warpage considerations. ...click to view
"Material Models in Simulation, Part 3: New viscosity models "
We discuss developments in viscosity modeling. New models are not generalized, but are designed to predict expected trends for polymers and incorporate both Newtonian and shear-thinning behavior.
...click to view
"Closing the Gap: Improving Solution Accuracy with Better Material Models "
We discuss open issues in material models for plastics and propose better means of acquiring the right material data for Moldflow simulations using current testing technologies.
...click to view
"Practical Issues in the Development and Implementation of Hyperelastic Models "
Hyperelastic models are used extensively in the finite element analysis of rubber and elastomers. These models need to be able to describe elastomeric behavior at large deformations and under different modes of deformation. In order to accomplish this daunting task, material models have been presented that can mathematically describe this behavior [1]. There are several in common use today, notably, the Mooney-Rivlin, Ogden and Arruda Boyce. Each of these has advantages that we will discuss in this article. Further, we will examine the applicability of a particular material model for a given modeling situation.
...click to view
"Methodology for Selection of Material Models for Plastics Impact Simulation "
The volume of plastics that are subjected to impact simulation has grown rapidly. In a previous paper, we discussed why different material models are needed to describe the highly varied behavior exhibited by these materials. In this paper, we cover the subject in more detail, exploring in depth, the nuances of commonly used LS-DYNA material models for plastics, covering important exceptions and criteria related to their use. ...click to view
"Characterization and Modeling of Non-linear Behavior of Plastics "
A considerable amount of CAE today is devoted to the simulation of non-metallic materials, many of which exhibit non-linear behavior. However, most material models to date are still based on metals theory. This places severe restrictions on the proper description of their behavior in CAE. In this paper, we describe non-linear elastic behavior and its interrelationship with plastic behavior in plastics. Special attention is given to the differentiation between visco-elastic (recoverable) strain and plastic (non-recoverable) strain. The goal of this work is to have a material model for plastics that can describe both loading and unloading behavior accurately and provide an accurate measure of damage accumulation during complex loading operations.
...click to view
"Material Modeling Strategies for Crash and Drop Test Simulation"
Many LS-DYNA models are used for plastics crash simulation. However, common models are not designed for plastics. We present best practices developed for adapting common models to plastics, as well as best testing protocols to generate clean, accurate rate-dependent data.
...click to view
"Material Modeling and Mold Analysis "
We present a perspective on material modeling as applied to mold analysis requirements. Melt-solid transitions and the case for a unified material model are discussed, along with prediction of post-filling material behavior and shrinkage, and the impact of viscous heating on flow behavior and material degradation.
...click to view
"Simulating Plastics in Drop and Crash Tests "
If you want a crash simulation involving plastics to yield useful results, it is important to model the material behavior appropriately. The high strain rates have a significant effect on the properties, and failure can be ductile or brittle in nature, depending on a number of factors.
...click to view
"Material Modeling of Soft Material for Non-linear NVH "
Abaqus’ Non-linear NVH capability permits the capture of material behavior of rubber seals and bushings, plastic parts and foam inserts which have a significant influence on the simulation. In this presentation, we discuss material calibration procedures for this application.
...click to view
"Selecting Material Models for the Simulation of Foams "
We seek to lay down a framework to help us understand the different behavioral classes of foams. Following a methodology that we previously applied to plastics, we will then attempt to propose the right LS-DYNA material models that best capture these behaviours. Guidelines for model selection will be presented as well as best practices for characterization. Limitations of existing material models will be discussed.
...click to view
"Characterization of Damage in Hyperelastic Materials Using Standard Test Methods and Abaqus"
Over the past couple of decades, standard test methods and material models have existed for rubber-like materials. These materials were classified under the category of Hyperelastic materials. Well established physical test methods and computational procedures exist for the characterization of the material behavior in tension, compression, shear volumetric response, tear strength etc. However, effective modeling of the fracture behavior of hyperelastic materials using finite element techniques is very challenging. In this paper, we make an attempt to demonstrate the use of such standard test methods and the applicability of such test data for performing finite element analyses of complex nonlinear problems using Abaqus. Our goal is to demonstrate the effective use of standard physical test data to model multi-axial loading situations and fracture of hyperelastic materials through tear tests and indentation test simulations.
...click to view
"The Need for Simulation-Quality Material Data"
Material testing for simulation is about understanding how to best describe a material’s behavior as input for the CAE code. Such testing requires expertise and experience beyond testing performed in a typical test laboratory; while the test instruments may be the same, the knowledge of CAE and experience with diverse materials is increasingly important. FEA software such as ANSYS is being increasingly used for non-linear simulations. We discuss how DatapointLabs' uncommon material expertise helps you avoid problems when the data is being generated these applications.
...click to view
"PhenQ Avis"
This book covers some of the most significant techniques used in modern analytical technology to characterize plastic and composite materials.
...click to view
"Behavior-based Material Model Selection and Calibration of Plastics for Crash Simulation "
Many material models are available for crash simulation. However, common models are not designed for plastics. We present best practices developed for adapting common models to plastics, as well as best testing protocols to generate clean, accurate rate-dependent data. In addition, we present a streamlined process to convert raw data to LS-DYNA material cards, and harmonized material datasets that allow the same raw data to be used for other crash and rate-dependent analysis software.
...click to view
"Material Testing and Calibration for Non-Linear ANSYS Simulations "
Material modeling has become increasing important as ANSYS software has added analysis capabilities such as non-linear CAE, crash, CFD, and manufacturing process simulation. Poor material representaion brings risk to CAE and product development. Material data needs for various material models are discussed.
...click to view
"Understanding and Coping with Material Modeling Limitations in FEA "
The limitations of modeling materials for simulation are discussed, including lack of clarity in material model requirements, gaps between the material data and the model to which it will be fitted, issues in obtaining pertinent properties, difficulties in parameter conversion (fitting), and preparation of input files for the software being used. Means to address these limitations are presented, including understanding the model completely, measuring the correct data with precision on the right material, selecting the best model for the data and ensuring the best fit of the model to the data, validating the model against a simple experiment, and following best practices to create an error-free input file.
...click to view
"Mechanical and Visco-Elastic Properties of UHMWPE for In-Vivo Applications "
Ultra-high molecular weight polyethylene (UHMWPE) is used extensively in orthopedic applications within the human body. Components made from these materials are subject to complex loading over extended periods of time. Modeling of components used in such applications depends heavily on having material data under in-vivo conditions. We present mechanical and visco-elastic properties measured in saline at 37C. Comparisons to conventionally measured properties at room temperature are made.
...click to view
"A Standardized Methodology for the DigimatMX Reverse Engineering Process "
We present a methodology for DIGIMAT users to perform the DIGIMAT MX reverse engineering process to obtain material parameter inputs for crash, elasto-plastic, creep and visco-elasticity. The injection-molding process used involves a standardized plaque geometry with fully developed flow, with test specimens taken from a specific plaque location. A standardized testing procedure is applied and the resulting DIGIMAT MX inputs are handled in a streamlined data stream, which saves time and improves the reliability of the reverse engineering process. The DIGIMAT MX reverse engineering itself can be performed as a service in collaboration with e-Xstream. This gives the user a speedy and tightly controlled process for performing complex finite element analysis with filled plastics
...click to view
"Testing for Crash & Safety Simulation"
The testing of materials for use in crash and safety simulations and the conversion of test data into material models is a process that is not well standardized in the industry. Consequently, CAE users face uncertainty and risk in this process that can have a negative impact on simulation quality. In this workshop, we present approaches currently used in the US for the gathering of high quality test data plus the acclaimed Matereality CAE Modeler software that is used to transform high strain-rate data into crash material cards.
...click to view
"Material Parameter Calibration Services for Abaqus Non-Linear Material Models"
DatapointLabs' TestPaks (material testing + model calibration + Abaqus input decks) for rate-dependent, hyperelastic, viscoelastic, NVH, and the use of Abaqus CAE Modeler to transform raw data into material cards will be presented. A representative from Idiada will present a case study explaining the use of DatapointLabs’ material data and TestPaks for simulation.
...click to view
"Applying Digital Image Correlation Methods to SAMP-1 Characterization "
SAMP-1 is a complex material model designed to capture non-Mises yield and localization behavior in plastics. To perform well, it is highly dependent on accurate post-yield material data. A number of assumptions and approximations are currently used to translate measured stress-strain data into the material parameters related to these inputs. In this paper, we look at the use of direct localized strain measurements using digital image correlation (DIC) as a way to more directly extract the required data needed for SAMP-1.
...click to view
"A Strategy for Material Testing and Data Management for the Automotive Industry "
Today, CAE is integrated with modern automotive product development. This creates new challenges for departments that support new product development. In the materials arena, the testing is elevated to much higher levels of sophistication and precision to accommodate the complex material models used in CAE. It is no longer simple matter to convert raw data into material model parameters. We present an end-to-end strategy that gives automakers a well managed pathway to transforming to simulation-based design. We operate a quick-turnaround expert material testing lab to support high-end CAE and product development. We provide a data management software designed specifically to capture and display material data of any complexity. The software can transform raw material data into material parameter files for most commonly used simulations. The CAE Modeler software is of adequate sophistication to fit equations to data, visualize material models along with raw data, and output material cards. Examples for high strain-rate crash material modeling will be presented.
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"Use of Digital Image Correlation to Obtain Material Model Parameters for Composites "
The development of material parameters for FEA is heavily reliant on precision material data that captures the stress-strain relationship with fidelity. While conventional methods involving UTMs and extensometers are quite adequate for obtaining such data on a number of materials, there are important cases where they have been known to be inadequate. The testing of composites to obtain directional properties remains a complex task because of the difficulty related to measuring these properties in different orientations. Digital Image Correlation (DIC) methods are able to capture the stress-strain relationship all the way to failure. In this paper, we combine DIC and conventional methods to measure directional properties of composites. We exploit the unique capability of DIC to retroactively place virtual strain gauges in areas of critical interest in the test specimen. Utilising an Iosipescu fixture, we measure shear properties of structured composites in a variety of orientations to compute the parameters of an orthotropic linear elastic material model. Model consistency is checked by validation using Abaqus.
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"Validating Simulation Using Digital Image Correlation "
There is interest in quantifying the differences between simulation and real life experimentation. This kind of work establishes a baseline for more complex simulations bringing a notion of traceability to the practice of CAE. We present the use of digital image correlation as a way to capture strain fields from component testing and compare these to simulation. Factors that are important in ensuring fidelity between simulation and experiment will be discussed.
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"The Use of Digital Image Correlation (DIC) and Strain Gauges to Validate Simulation "
As part of Cornell University's mechanical engineering curriculum and study of classical beam theory, an aluminium beam is deformed to a specific load. Theoretical strains are calculated at certain points along the beam using beam theory, and then verified by using strain gauges placed at these points on the beam. This experiment is then extended to simulation of the same test setup in simulation software, where strains are analyzed at the same points. Discrepancies between the simulation, theory, and strain gauge results have often plagued the test, especially when incorporating more complex beam design. Through use of digital image correlation (DIC) it is possible to pinpoint some of the problem areas in the beam analysis and provide a better understanding of the localized strains that occur at any point in the deformed beam. The use of DIC provides a full field validation of simulation data, rather than a single spot check that strain gauges can provide. This validation technique helps to eliminate error that is associated with strain gauge placement and the possibility of missing strain hot spots that can arise when analyzing complex deformations or geometries.
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"Providing an Experimental Basis in Support of FEA "
The use of CAE in design decision-making has created a need for proven simulation accuracy. The two areas where simulation touches the ground are with material data and experimental verification and validation (V&V). Precise, well designed and quantitative experiments are key to ensure that the simulation initiates with correct material behavior. Similar validation experiments are needed to verify simulation and manage the risk associated with this predictive technology.
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"Comments on the Testing and Management of Plastics Material Data "
Plastics appeared as design materials of choice about 30 years ago. They brought with them huge design challenges because their multi-variable, non-linear nature was not well understood by engineers trained to work in a linear elastic world. We outline a 20 year journey accompanying our customers in their efforts to understand and simulate these remarkable materials to produce the highly reliable plastic products of today. We discuss challenges related to processes such as injection molding vs. blow-molding; coping with filled plastics; the difficulties of modeling polymers for crash applications. We include our latest findings related to volumetric yield in polymers and its relationship to failure. We describe the material database technology that was created to store this kind of multi-variable data and the analytical tools created to help the CAE engineer understand and use plastics material data.
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"Software for Creating and Managing Material Specifications "
Material specifications define properties for incoming materials to meet required criteria. We present software that manages creation of material specifications, input of properties and material composition; and provides a way to evaluate qualification per specification. While it is designed for OEM/Tier n environments, it is also applicable for materials suppliers.
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"Plastics & Simulation "
Plastics exhibit non-linear viscoelastic behavior followed by a combination of deviatoric and volumetric plastic deformation until failure. Capturing these phenomena correctly in simulation presents a challenge because of the inadequacy of currently used material models. We follow an approach where we outline the general behavioral phenomena, then prescribe material models for handling different phases of plastics deformation. Edge cases will then be covered to complete the picture. Topics to be addressed include: Using elasto-plasticity; When to use hyperelasticity; Brittle polymers – filled plastics; Failure modes to consider; Criteria for survival; Choosing materials; Spatial non-isotropy from injection molding; Importance of residual stress; Visco-elastic and creep effects; Strain-rate effects for drop test and crash simulations; Fitting material data to FEA material models.
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"Finite Element Analysis of Additively Manufactured Products"
With the growing interest in 3D printing, there is a desire to accurately simulate the behavior of components made by this process. The layer by layer print process appears to create a morphology that is different from that from conventional manufacturing processes. This can have dramatic impact on the material properties, which in turn, can affect how the material is modeled in simulation. In the first stage of our work, we seek to test an additively manufactured material for mechanical properties and validate its use in ANSYS simulation using the Cornell Bike Crank model. ...click to view
"Comparison of Crash Models for Ductile Plastics"
There is interest in quantifying the accuracy of different material models being used in LS-DYNA today for the modeling of plastics. In our study, we characterize two ductile, yet different materials, ABS and polypropylene for rate dependent tensile properties and use the data to develop material parameters for the material models commonly used for plastics: MAT_024 and its variants, MAT_089 and MAT_187. We then perform a falling dart impact test which produces a complex multi-axial stress state and simulate this experiment using LS-DYNA. For each material model we are able to compare simulation to actual experiment thereby obtaining a measure of fidelity of the simulation to reality. In this way, we can assess the benefits of using a particular material model for plastics simulation. ...click to view
"Thermoplastic Material Testing for Use in SIGMASOFT and the Effect of Moisture on PA 6/6"
Thermoplastic materials are one of the largest categories of materials to be injection molded. Moisture-sensitive materials can lead to issues in the molding process. Simulation of the injection molding process requires sophisticated and exact material properties to be measured. This presentation discusses the testing required to characterize a thermoplastic material for use in SIGMASOFT, as well as the effects of moisture on viscosity measurement of a moisture-sensitive material. Consequences of basing designs on wet or dry materials are covered. Implementation of material data into the software to produce a successful injection molding simulation simulation is described. ...click to view
"A Standardized Mechanism to Validate Crash Models for Ductile Plastics - PREPRINT"
Quantifying simulation accuracy before running crash simulations could be a helpful confidence building measure. This study continues our development of a mechanism to validate material models for plastics used in modeling high-speed impact. Focusing on models for isotropic materials that include options for rate dependency and failure, we explore other models commonly used for ductile plastics including MAT089 and MAT187. ...click to view
"Using an Intermediate Validation Step to Increase CAE Confidence - PREPRINT"
Simulations contain assumptions and uncertainties that a designer must evaluate to obtain a measure of accuracy. The assumptions of the product design can be differentiated from the ones for the solver and material model through the use of a mid-stage validation. An open loop validation uses a controlled test on a standardized part to compare results from a simulation to the physical experiment. From the validation, confidence in the material model and solver is gained. In this study, the material properties of a polypropylene are tested to characterize for an *ELASTIC *PLASTIC model in ABAQUS. A validation of a quasi-static three-point bending experiment of a parallel ribbed plate is then performed and simulated. A comparison of the strain fields resulting from the complex stress state on the face of the ribs obtained by digital image correlation (DIC) vs. simulation is used to quantify the simulation's fidelity. ...click to view
"A Design–Validation-Production Workflow for Aerospace Additive Manufacturing - EXTENDED ABSTRACT"
With the advent of 3D printing and additive manufacturing, manufacturing designs previously thought difficult to produce can now be generated quickly and efficiently and without tooling. In the aerospace industry, weight is often tied directly to cost and is thus of great importance to any engineering design. Traditionally, the design process often involves much iteration between the designer and the analyst, where the designer submits a design to the analyst, and then the analyst completes his or her analysis and sends recommendations back to the designer. The process is repeated until a valid design meets the analysis criteria. The design is then handed to the manufacturing team which then may have additional constraints or concerns and iterations can continue. Additive manufacturing coupled with topology optimization allows the design and analysis loops and manufacturing iterations to be reduced significantly or even eliminated. The critical step is to ensure that the part will perform as simulated. ...click to view
"A Design–Validation-Production Workflow for Aerospace Additive Manufacturing - PRESENTATION"
Megan Lobdell, Brian Croop, Hubert Lobo (DatapointLabs); Robert Yancey, Sridhar Ravikoti, Leo Jeng, Aaron Leinmiller (Altair Engineering)
With the advent of 3D printing and additive manufacturing, manufacturing designs previously thought difficult to produce can now be generated quickly and efficiently and without tooling. In the aerospace industry, weight is often tied directly to cost and is thus of great importance to any engineering design. Traditionally, the design process often involves much iteration between the designer and the analyst, where the designer submits a design to the analyst, and then the analyst completes his or her analysis and sends recommendations back to the designer. The process is repeated until a valid design meets the analysis criteria. The design is then handed to the manufacturing team which then may have additional constraints or concerns and iterations can continue. Additive manufacturing coupled with topology optimization allows the design and analysis loops and manufacturing iterations to be reduced significantly or even eliminated. The critical step is to ensure that the part will perform as simulated. ...click to view
"Using an Intermediate Validation Step to Increase CAE Confidence - PRESENTATION"
Christopher Wolfrom (Cornell University); Megan Lobdell, Hubert Lobo, Brian Croop (DatapointLabs)
Simulations contain assumptions and uncertainties that a designer must evaluate to obtain a measure of accuracy. The assumptions of the product design can be differentiated from the ones for the solver and material model through the use of a mid-stage validation. An open loop validation uses a controlled test on a standardized part to compare results from a simulation to the physical experiment. From the validation, confidence in the material model and solver is gained. In this study, the material properties of a polypropylene are tested to characterize for an *ELASTIC *PLASTIC model in ABAQUS. A validation of a quasi-static three-point bending experiment of a parallel ribbed plate is then performed and simulated. A comparison of the strain fields resulting from the complex stress state on the face of the ribs obtained by digital image correlation (DIC) vs. simulation is used to quantify the simulation's fidelity. ...click to view
"A Standardized Mechanism to Validate Crash Models for Ductile Plastics - PRESENTATION"
Megan Lobdell, Brian Croop, Hubert Lobo
Quantifying simulation accuracy before running crash simulations could be a helpful confidence building measure. This study continues our development of a mechanism to validate material models for plastics used in modeling high-speed impact. Focusing on models for isotropic materials that include options for rate dependency and failure, we explore other models commonly used for ductile plastics including MAT089 and MAT187. ...click to view
"A Mechanism for the Validation of Hyperelastic Materials in ANSYS - PAPER"
Hyperelastic material models are complex in nature requiring stress-strain properties in uniaxial, biaxial and shear modes. The data need to be self-consistent in order to fit the commonly used material models. Choosing models and fitting this data to these equations adds additional uncertainty to the process. We present a validation mechanism where, using of a standard validation experiment one can compare results from a simulation and a physical test to obtain a quantified measure of simulation quality. Validated models can be used with greater confidence in the design of real-life components. ...click to view
"A Mechanism for the Validation of Hyperelastic Materials in ANSYS - PRESENTATION"
Hyperelastic material models are complex in nature requiring stress-strain properties in uniaxial, biaxial and shear modes. The data need to be self-consistent in order to fit the commonly used material models. Choosing models and fitting this data to these equations adds additional uncertainty to the process. We present a validation mechanism where, using of a standard validation experiment one can compare results from a simulation and a physical test to obtain a quantified measure of simulation quality. Validated models can be used with greater confidence in the design of real-life components. ...click to view
"Testing, Modeling and Validation for Plastics & Rubber Simulation in ANSYS - part 1 of 5"
Role of Materials in Simulation: reducing materials risk through testing, modeling, validation, management and knowledge capture ...click to view
"Testing, Modeling and Validation for Plastics & Rubber Simulation in ANSYS - part 2 of 5"
Plastics: testing, modeling and model validation ...click to view
"Testing, Modeling and Validation for Plastics & Rubber Simulation in ANSYS - part 3 of 5"
Hyperelastic: testing, modeling and model validation ...click to view
"Testing, Modeling and Validation for Plastics & Rubber Simulation in ANSYS - part 4 of 5"
Creep/Stress Relaxation/Viscoelastic/Fiber-filled: testing, modeling ...click to view
"Testing, Modeling and Validation for Plastics & Rubber Simulation in ANSYS - part 5 of 5"
Rate Dependent: testing, modeling and model validation ...click to view
"Using Mid-stage Validation to Increase Confidence in Simulation of TPOs - Presentation"
Finite element analysis of plastics contains assumptions and uncertainties that can affect simulation accuracy. It is useful to quantify these effects prior to using simulation for real-life applications. A mid-stage validation uses a controlled physical test on a standardized part to compare results from simulation to physical experiment. These validations do not use real-life parts but carefully designed geometries that probe the accuracy of the simulation; the geometries themselves can be tested with boundary conditions that can be simulated correctly. In one study, a quasi-static three-point bending experiment of a standardized parallel ribbed plate is performed and simulated, using Abaqus. A comparison of the strain fields resulting from the complex stress state on the face of the ribs obtained by digital image correlation (DIC) vs. simulation is used to quantify the simulation's fidelity. In a second study, a dynamic dart impact experiment is validated using LS-Dyna probing the multi-axial deformation of a polypropylene until failure. ...click to view
"The Role of Material Data in the Simulation of Injection Molded Parts "
PDF of presentation delivered at the SPE IMTECH 2017 Conference. ...click to view
"A Framework for the Calibration and Validation of Multiscale Material Models - presentation"
Simulation of composites ...click to view
"Improving Simulation Quality with Reliable Materials Methods - Presentation"
Keynote address delivered at NAFEMS seminar on "Material Properties in Structural Calculation: Modeling, Calibration, Simulation & Optimization." ...click to view
"Materials Data Workflow for Simulation of Composites in Transportation Applications - presentation"
Presented by Hubert Lobo at JEC World 2019, March 13, 2019 ...click to view
"Validation of Simulation - presentation"
Presented by Hubert Lobo at the TechNet Alliance Fall Meeting; Bilbao, Spain; October 6-7, 2017 ...click to view
"Mid-Stage Validation as a Process Step in Simulation V&V - presentation"
Presented by Hubert Lobo at NAFEMS World Conference 2017, Stockholm, Sweden ...click to view
"Mid-Stage Validation as a Process Step in Simulation V&V - paper"
Physically accurate simulation is a requirement for initiatives such as late-stage prototyping, additive manufacturing and digital twinning. The use of mid-stage validation has been shown to be a valuable tool to measure solver accuracy prior to use in simulation. Factors such as simulation settings, element type, mesh size, choice of material model, the material model parameter conversion process, quality and suitability of material property data used can all be evaluated. These validations do not use real-life parts, but instead use carefully designed standardized geometries in a controlled physical test that probes the accuracy of the simulation. With this a priori knowledge, it is possible to make meaningful design decisions. Confidence is gained that the simulation replicates real-life physical behavior. We present three case studies using different solvers and materials, which illustrate the broad applicability of this technique. ...click to view
"Insights into the Simulation of Failure of Ductile Plastics - presentation"
Presented by Hubert Lobo at CARHS Automotive CAE Grand Challenge 2017. ...click to view
"Datapoint Newsletter Vol. 27.3 - PDF"
Datapoint v27.3 printer friendly PDF ...click to view
"Material Testing for SIGMASOFT - Presentation"
Material Testing for SIGMASOFT ...click to view
"Beyond Standards: Material Testing and Processing for Successful Simulations of Foam Materials (LAW90) - Presentation, long version"
Long version of presentation used for online conference proceedings ...click to view
"Beyond Standards: Material Testing and Processing for Successful Simulations of Foam Materials (LAW90) - Presentation, short version"
Presentation as delivered in person. ...click to view
"Integrated Experimental Analysis, Modeling, and Validation of High-Performance UD CFRTP Lamina: PRESENTATION"
CARHS Automotive CAE Grand Challenge 2024 presentation ...click to view
"Beyond Standards: Material Testing and Processing for Successful Simulations of Polymeric Materials (LAW76): PRESENTATION"
Presented at OpenRadioss Users' Day 2024 ...click to view