July 31, 2015 | by Massimo Nutini | views 4434
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.
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Mechanical
Plastics
Automotive
Biomedical
Structural Analysis
Abaqus
Research Papers
Validation
June 12, 2009 | by DatapointLabs | views 4423
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.
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Rubbers
Material Supplier
Industrial Goods
Nonlinear Material Models
Structural Analysis
Abaqus
Research Papers
September 23, 2015 | by DatapointLabs | views 4419
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
November 11, 2015 | by Altair Engineering | views 4413
[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.
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Mechanical
Aerospace and Defense
Automotive
Injection Molding
Structural Analysis
Moldex3D
DIGIMAT
Papers
Altair RADIOSS
Newsletters
Validation
July 27, 2015 | by Paul Du Bois | views 4407
"A general purpose orthotropic elasto-plastic computational constitutive material model has been
developed to accurately predict the response of composites subjected to high velocity impact.
The three-dimensional orthotropic elasto-plastic composite material model is being implemented
initially for solid elements in LS-DYNA® as MAT213. In order to accurately represent the
response of a composite, experimental stress-strain curves are utilized as input, allowing for a
more general material model that can be used on a variety of composite applications. The
theoretical details are discussed in a companion paper. This paper documents the
implementation, verification and validation of the material model using the T800-F3900
fiber/resin composite material."
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Mechanical
Plasticity
Yielding/Failure Analysis
Aerospace and Defense
Automotive
High Speed Testing
LS-DYNA
Composites
Research Papers
Validation
July 27, 2015 | by Paul Du Bois | views 4398
"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."
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Mechanical
Metals
Yielding/Failure Analysis
Aerospace and Defense
High Speed Testing
LS-DYNA
Research Papers
Validation
July 21, 2010 | by DatapointLabs | views 4391
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.
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Plastics
Rubbers
Foams
Aerospace and Defense
Automotive
Biomedical
Consumer Products
Material Supplier
Toys/Sporting Goods
Electonics/Electrical
Industrial Goods
Packaging
Home Appliances
Presentations
April 29, 2015 | by Patrick Cunningham | views 4387
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.
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Plastics
Plasticity
Presentations
August 26, 2015 | by Massimo Nutini | views 4379
The airbag door system is one of the most delicate aspects in the design phase of a car instrument panel: seamless systems are increasingly used, which combine styling criteria with good functional performances. These systems typically include a tear seam, which may be obtained through laser scoring, to pre-determine the location of the opening during airbag deployment. The design of the scoring line is currently validated through experimental tests on real life exemplars, submitted to airbag deployment, resulting in high development times and relevant costs. This is the main reason which suggests proposing numerical simulation in the design phase, not to substitute actual part homologation by testing but in order to limit the scope and complexity of the experimental campaign, thus reducing the development costs and the time to market. So far, modeling the scoring line has been difficult due to limitations in the testing methods and simulation codes available to the industry. The methodology proposed in this paper takes advantage from the availability of a material law as LS-Dyna SAMP-1, with polymer-dedicated plasticity, damage model and strain-rate dependent failure criteria, which is supported by local strain measurement used for material characterization. The method, here described in detail, is validated on a benchmark test, consisting in the real and virtual testing on a variety of scoring profiles obtained on a polypropylene box submitted to high speed impact test.
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Plasticity
Yielding/Failure Analysis
Automotive
High Speed Testing
LS-DYNA
Research Papers
Validation
February 13, 2014 | by DatapointLabs | views 4369
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
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