April 06, 2017 | by DatapointLabs | views 4858
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 6198
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.
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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 5440
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.
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Mechanical
Hyperelastic
Structural Analysis
ANSYS
Papers
Presentations
Validation
October 04, 2016 | by DatapointLabs | views 4828
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.
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Mechanical
Plastics
Automotive
Structural Analysis
LS-DYNA
Abaqus
Presentations
Validation
July 05, 2016 | by Hubert Lobo | views 4852
We will focus on our work related to the testing, modeling and validation of simulation for crash
and durability applications, including testing techniques, software tools for material parameter conversion, and
the use of a mid-stage validation process that uses standardized experiments to check the accuracy of the simulation prior to use in real-life applications. In addition, we present a short introduction to the Knowmats initiative which seeks to collect posts and links to papers from industry experts as a reference for simulation professionals.
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Mechanical
Plastics
Automotive
High Speed Testing
Nonlinear Material Models
Structural Analysis
Universal Crash
Presentations
Validation
June 24, 2016 | by Massimo Nutini | views 5180
Topics covered: Damage in mineral filled polypropylene under impact conditions; damage modeling and parameter identification (prior art, LyondellBasell contributions, debate in the CAE community); experimental and numerical validation; next steps
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Mechanical
Plastics
Rate Dependency
Yielding/Failure Analysis
Automotive
Material Supplier
High Speed Testing
LS-DYNA
Presentations
June 13, 2016 | by DatapointLabs | views 5631
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
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