April 30, 2014 | by DatapointLabs | views 5495
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
July 27, 2015 | by Paul Du Bois | views 5491
"To assess the problem of containment after a blade-off accident in an aero-engine by numerical
simulation the FAA has instigated a research effort concerning failure prediction in a number of
relevant materials. Aluminium kicked off the program which involved an intensive testing program
providing failure data under different states of stress, different strain rates and different temperatures.
In particular split Hopkinson bars were used to perform dynamic punch tests on plates of different
thicknesses allowing to investigate the transition between different failure modes such as petaling and
plugging. Ballistic impact tests were performed at NASA GRC for the purpose of validation.
This paper focuses on the numerical simulation effort and a comparison with experimental data is
done. The simulations were performed with LS-DYNA and a tabulated version of the Johnson-Cook
material law was developed in order to increase the generality, flexibility and user-friendliness of the
material model."
...read full post
Mechanical
Metals
Yielding/Failure Analysis
Aerospace and Defense
High Speed Testing
LS-DYNA
Research Papers
Validation
July 22, 2015 | by Paul Du Bois | views 5490
"Reliable prediction of the behaviour of structures made from polymers is a topic
under considerable investigation in engineering practice. Especially, if the
structure is subjected to dynamic loading, constitutive models considering the
mechanical behaviour properly are still not available in commercial finite element
codes.
First, we give an overview of material laws for thermoplastics and show how the
behaviour can be characterized and approximated by using visco-elasticity and
metal plasticity, respectively. Experimental work is presented to point out
important phenomena like necking, strain rate dependency, unloading behaviour
and damage. A constitutive model including the experimental findings is derived.
In particular, different yield surfaces in compression and tension and strain rate
dependent failure, the latter with damage induced erosion, need to be taken into
account. With the present formulation, standard verification tests can be
simulated successfully. Also, an elastic damage model is used to approximate
the unloading behaviour of thermoplastics adequately."
...read full post
Mechanical
Rate Dependency
Yielding/Failure Analysis
Automotive
High Speed Testing
LS-DYNA
Research Papers
November 11, 2015 | by Altair Engineering | views 5478
[We] introduced the topic of injection molding process simulation and the influence of the manufacturing process on structural analysis. The strength and stiffness of a part can be inaccurately represented if the manufacturing process conditions are not properly considered. This results in a different calculation of system natural frequencies or improper estimation of the energy absorbing characteristics. We continue on this topic, extending the scope to advanced technologies available in the Altair Partner Alliance (APA) to help solve the problem of proper design validation with fiber reinforced plastics.
...read full post
Mechanical
Aerospace and Defense
Automotive
Injection Molding
Structural Analysis
Moldex3D
DIGIMAT
Papers
Altair RADIOSS
Newsletters
Validation
April 29, 2015 | by Patrick Cunningham | views 5476
This demonstration showing how to analyze plastic parts using finite element analysis was given by Patrick Cunningham at CAE Associates' Accurate FEA of Engineering Plastics seminar, held on October 14, 2014 in Tarrytown, NY.
...read full post
Plastics
Plasticity
Presentations
July 15, 2003 | by DatapointLabs | views 5474
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
March 10, 2011 | by DatapointLabs | views 5471
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
June 12, 2009 | by DatapointLabs | views 5463
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
July 31, 2015 | by Massimo Nutini | views 5460
Notwithstanding the increasing demand for polymeric materials in an
extraordinary variety of applications, the engineers have often only limited tools suitable for
the design of parts made of polymers, both in terms of mathematical models and reliable
material data, which together constitute the basis for a finite-elements based design.
Within this context, creep modelling constitutes a clear example of the needs for a more
refined approach. An accurate prediction of the creep behaviour of polymers would definitely
lead to a more refined design and thus to a better performance of the polymeric components.
However, a limited number of models is available within the f.e. codes, and when the model
complexity increases, it becomes sometimes difficult fitting the models parameters to the
experimental data.
In order to predict the polymer creep behaviour, this paper proposes a solution based on
artificial neural networks, where the experimental creep curves are used to determine the
parameters of a neural network which is then simply implemented in an Abaqus user
subroutine.
This allows to avoid the implementation of a complex material law and also the difficulties
related to match the experimental data to the model parameters, keeping easily into account
the dependence on stress and temperature.
After a discussion of the selection of the appropriate network and its parameters, an example
of the application of this approach to polyolefins in a simplified test case is presented.
...read full post
Mechanical
Plastics
Automotive
Biomedical
Structural Analysis
Abaqus
Research Papers
Validation
August 24, 2015 | by Massimo Nutini | views 5458
Glass-fiber-reinforced polypropylene (GF PP) materials are increasingly being used by customers to replace metal and engineering polymers in structural automotive applications. Like all glass-fiber reinforced thermoplastics, GF PP products can show anisotropy caused by fiber orientation that is induced by the injection process. Taking into account fiber orientation in the simulations enables designers to improve the accuracy of the analyses. This can help prevent arbitrary choices and assumptions when setting material parameters, which become mandatory when an isotropic material law is used. The method proposed in this paper takes advantage of the availability within Ls-dyna of an anisotropic material law (MAT_103), which allows simplified modeling to address critical issues. This law was not developed to address the problem discussed here.
Therefore, this paper illustrates a simplified approach. The presence of glass reinforced fibers is taken into account by running a mold-filling analysis, and then transferring the material flow orientation in to the structural simulation as a material angle. The dependence of the material failure strain on the material orientation can be also easily modeled through a user subroutine. Finally, the approach only requires simple material data based on basic tensile tests; the material law parameters are then identified through optimization techniques. Although this approach is based on some simplifying assumptions, its application is quick and can help the designer obtain more accurate results with respect to the traditional isotropic approach. A selection of validation tests is then proposed that show reliable predictions using limited additional computational effort.
...read full post
Mechanical
Plastics
Rate Dependency
Automotive
High Speed Testing
LS-DYNA
Research Papers
tweet
share
share