March 08, 2021 | by Datapoint Newsletters | views 3400
DatapointLabs Will Move, Summer '21; Get Your Testing in Now. Partner Showcase: Altair
High Speed Testing Structural Analysis Composites Altair RADIOSS Newsletters
September 16, 2019 | by Datapoint Newsletters | views 4539
New DatapointLabs Website; High Temperature Crash Properties
Density Rheology Thermal Mechanical Plastics Automotive High Speed Testing Injection Molding Structural Analysis LS-DYNA ANSYS DIGIMAT Composites Newsletters Validation
February 05, 2018 | by Datapoint Newsletters | views 6289
Focus on Validation of Simulation: CAETestBench Validation for crash, additive manufacturing, injection molding, rubber hyperelasticity; Review of NAFEMS publication on V&V.
Plastics Rubbers Metals High Speed Testing Injection Molding Structural Analysis LS-DYNA Abaqus ANSYS Altair RADIOSS Newsletters Validation 3D Printing OptiStruct
April 06, 2017 | by DatapointLabs | views 4914
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.
Mechanical Plastics Automotive High Speed Testing Nonlinear Material Models Structural Analysis Universal Crash Presentations Validation
January 31, 2017 | by Datapoint Newsletters | views 7203
New test capabilities, Matereality v10.2, upcoming presentations
Mechanical Plastics Rubbers Hyperelastic Viscoelastic Rate Dependency High Speed Testing Structural Analysis Composites Newsletters Validation
September 08, 2016 | by Datapoint Newsletters | views 5492
Support for GISSMO, New Book, SDPD Workflow for Materials
Mechanical High Speed Testing Nonlinear Material Models Structural Analysis LS-DYNA Newsletters Validation
July 05, 2016 | by Hubert Lobo | views 4885
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.
Mechanical Plastics Automotive High Speed Testing Nonlinear Material Models Structural Analysis Universal Crash Presentations Validation
June 24, 2016 | by Massimo Nutini | views 5210
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
Mechanical Plastics Rate Dependency Yielding/Failure Analysis Automotive Material Supplier High Speed Testing LS-DYNA Presentations
June 13, 2016 | by DatapointLabs | views 5677
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.
Mechanical Plastics Rate Dependency Yielding/Failure Analysis Automotive Toys/Sporting Goods Packaging High Speed Testing LS-DYNA Research Papers Validation
June 03, 2016 | by DatapointLabs | views 8054
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.
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
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.
Plasticity Yielding/Failure Analysis Automotive High Speed Testing LS-DYNA Research Papers Validation
August 24, 2015 | by Massimo Nutini | views 4453
Optical strain measurement for the mechanical characterization of polymers, and in particular of polyolefins, is becoming a common practice to determine the parameters to be used in a finite element analysis of crash problems. This experimental technique allows measuring the strain locally on the specimen, so that it is particularly suitable when the deformation is localized, as in the case of polymers: therefore a more accurate description of the behaviour of the material is obtained. By so doing, it is possible to describe the material constitutive law in terms of the true, local strain and of the true stress. As these data are those needed by the most complete material models developed for impact calculation, it is clear that this technique is particularly suitable for coupling with the most advanced material models currently available in the F.E. codes, as for instance with Mat 187 (SAMP-1) of LS-Dyna. The local measurement of the strain can also be used for evaluating the volume strain, whose evolution with the increasing strain shows that for PP-based material the deformation is not isochoric in most the cases. The observed increase in the material volume reflects the fact that voids generate and coalesce within the material, possibly resulting in fracture. The measure of the volume strain, computed as the trace of the strain tensor, is here used for determining the damage function utilized by the damage model implemented in SAMP-1. The effective stress is here estimated as the stress which would be measured if the deformation was isochoric, and it can be assessed on the basis of the measurement of the longitudinal local strain only. Corresponding to each value of longitudinal strain, the volume strain is then used to calculate the ratio between the effective and the true stress. Adopting this procedure, the damage function is thus determined without the needs of repeated loading-unloading tests used to derive the damage parameter from the unloading slope, which is furthermore difficult to be measured. As an application, the results of the numerical reproduction of a benchmark test, consisting in a drop test on a polypropylene box, are presented and discussed
Mechanical Plastics Rate Dependency Yielding/Failure Analysis Automotive High Speed Testing LS-DYNA Research Papers
August 24, 2015 | by Massimo Nutini | views 4309
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.
Mechanical Plastics Rate Dependency Automotive High Speed Testing LS-DYNA Research Papers
July 31, 2015 | by Massimo Nutini | views 4173
Questo articolo si propone di illustrare l’importanza dell’utilizzo di metodi per la misura delle proprietà locali del materiale per determinarne la legge di comportamento. Vengono di seguito presentati alcuni esempi che evidenziano quanto più accurate e realistiche siano le simulazioni numeriche di test di trazione ad alta velocità su provini di poliolefine, quando vengano utilizzate proprietà dei materiali rilevate con misure locali, utilizzando metodi ottici. La disponibilità di misure locali e più accurate evidenzia come sia necessario che nei codici di calcolo commerciali vengano implementate delle leggi di materiale più sofisticate di quelle disponibili attualmente, che sono state per lo più originariamente sviluppate per materiali metallici, e dunque non riescono sempre a predire correttamente il comportamento dei componenti in materiali polimerici.
Mechanical Plastics Rate Dependency Automotive High Speed Testing LS-DYNA Research Papers
July 30, 2015 | by Helmut Gese | views 3995
"In sheet-metal-forming the forming limit curve (FLC) is used for ductile sheets to predict fracture in deep drawing. However the use of the FLC is limited to linear strain paths. The initial FLC cannot be used in a complex nonlinear strain history of a deep drawing process or a successive stamp and crash process including a significant change in strain rate. The CRACH software has been developed to predict the forming limit of sheets for nonlinear strain paths [1]. It has been validated to predict instability for bilinear strain paths with static loading in the first path and dynamic loading in the second path for mild steels [2]. As the postprocessing of strain paths from single finite elements in CRACH is not economic for industrial applications MATFEM initiated a project to couple CRACH directly with FEM-Code LS-DYNA using a userdefined material model. This allows a prediction of possible failure during the simulation for all elements with respect to their complete strain history. A special strategy has been developed to include CRACH without extensive increase in total CPU time. The developed interface to LS-DYNA allows also the implementation of other failure criteria demanding the history of deformation like for example a tensorial fracture criterion. In order to test the reliability of the calculated safety factor experimental tests for bilinear strain paths have been simulated [2]. In this case the experimental and numerical investigations have been made on two-stage forming processes (static in the 1st stage and both static/dynamic in the 2nd stage) . The static-static case should simulate a stamping process with bilinear strain path. The static-dynamic case should simulate a successive stamp and crash process. The simulation of a complex deep drawing problem including areas with significantly nonlinear strain paths has been simulated with LS-DYNA/CRACH-coupling. It can be shown that the prediction of CRACH can differ significantely from a “standard” prediction based on the initial FLC. The coupling of LS-DYNA and CRACH showed the potential to predict possible fracture in deep drawing and crash loading at an early design stage and allowed to optimise geometry and material quality to significantly reduce later problems in real components."
Mechanical Metals Rate Dependency Yielding/Failure Analysis Automotive High Speed Testing LS-DYNA Research Papers
July 30, 2015 | by Helmut Gese | views 4519
"Today the automotive industry is faced with the demand to build light fuel-efficient vehicles while optimizing its crashworthiness and stiffness. A wide variety of new metallic and polymeric materials have been introduced to account for these increased requirements. Numerical analysis can significantly support this process if the analysis is really predictive. Within the numerical model a correct characterization of the material behaviour – including elasto-viscoplastic behaviour and failure - is substantial. The particular behaviour of each material group must be covered by the material model. The user material model MF GenYld+CrachFEM allows for a modular combination of phenomenological models (yield locus, strain hardening, damage evolution, criteria for fracture initiation) to give an adequate representation of technical materials. This material model can be linked to LS-DYNA when using the explicit-dynamic time integration scheme. This paper gives an overview on the material characterization of ultra high strength steels (with focus on failure prediction), non-reinforced polymers (with focus on anisotropic hardening of polymers), and structural foams (with focus on compressibility and stress dependent damage evolution) with respect to crash simulation. It will be shown that a comprehensive material model - including damage and failure behaviour - enables a predictive simulation without iterative calibration of material parameters. A testing programme has been done for each material group in order to allow a fitting of the parameters of the material model first. In a second step different component tests have been carried out, which were part of a systematic procedure to validate the appropriate predictions of the crash behaviour with LS-Dyna and user material MF_GenYld+CrachFEM for each material group."
Mechanical Plastics Foams Metals Rate Dependency Yielding/Failure Analysis Automotive High Speed Testing LS-DYNA Research Papers
July 30, 2015 | by Helmut Gese | views 4299
"The Crash Simulation of Magnesium Structures with Finite Element Methods demands the use of suitable material and failure models. An associated plasticity model describing the complex asymmetric yield behaviour in tension and compression of Mg extrusions has been developed during the InMaK-project (Innovative Magnesium Compound Structures for Automobile Frames) supported by the German Federal Ministry for Education and Research (BMBF). Differences to the material model 124 in LS-DYNA are exposed. In order to describe the failure behaviour of Mg extrusions under multiaxial loading in FEM crash simulation this constitutive model has been combined with a fracture model for ductile and shear fracture. The fracture model has been added to the user defined constitutive magnesium model in LS-DYNA. The experimental investigations carried out on model components are compared with numerical derived results. Experimental methods for fracture parameter evaluation are shown and general aspects of metal failure due to fracture as well as different modelling techniques are discussed."
Mechanical Metals Rate Dependency Yielding/Failure Analysis Automotive High Speed Testing LS-DYNA Research Papers
July 28, 2015 | by Paul Du Bois | views 4717
FAA William J Huges Technical Center (NJ) conducts a research project to simulate failure in aeroengines and fuselages, main purpose is blade-out containment studies. This involved the implementation in LS-DYNA of a tabulated generalisation of the Johnson-Cook material law with regularisation to accommodate simulation of ductile materials.
Mechanical Metals Rate Dependency Yielding/Failure Analysis Aerospace and Defense Automotive High Speed Testing LS-DYNA Presentations Validation
July 27, 2015 | by Paul Du Bois | views 4795
The need for accurate material models to simulate the deformation, damage and failure of polymer matrix composites is becoming critical as these materials are gaining increased usage in the aerospace and automotive industries. While there are several composite material models currently available within LS-DYNA, there are several features that have been identified that could improve the predictive capability of a composite model. To address these needs, a combined plasticity and damage model suitable for use with both solid and shell elements is being developed and is being implemented into LS-DYNA as MAT_213. A key feature of the improved material model is the use of tabulated stress-strain data in a variety of coordinate directions to fully define the stress-strain response of the material. To date, the model development efforts have been focused on creating the plasticity portion of the model. The Tsai-Wu development efforts have focused on creating the plasticity portion of the model. The Tsai-Wu composite failure model has been generalized and extended to a strain-hardening based orthotropic material model with a non-associative flow rule. The coefficients of the yield function, and the stresses to be used in both the yield function and the flow rule are computed based on the input stress-strain curves using the effective plastic strain as the tracking variable. The coefficients in the flow rule are computed based on the obtained stress-strain data. The developed material model is suitable for implementation within LS-DYNA for use in analyzing the nonlinear response of polymer composites.
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 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."
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 4534
"Recently new materials were introduced to enhance different aspects of automotive safety while minimizing the weight added to the vehicle. Such foams are no longer isotropic but typically show a preferred strong direction due to their manufacturing process. Different stress/ strain curves are obtained from material testing in different directions. A new material model was added to the LS-DYNA code in order to allow a correct numerical simulation of such materials. Ease-of-use was a primary concern in the development of this user-subroutine: we required stress/ strain curves from material testing to be directly usable as input parameters for the numerical model without conversion. The user-subroutine is implemented as MAT_TRANSVERSELY_ANISOTROPIC_CRUSHABLE_FOAM, Mat law 142 in LS-DYNA Version 960-1106. In this paper we summarize the background of the material law and illustrate some applications in the field of interior head-impact. The obvious advantage of incorporating such detail in the simulation lies in the numerical assessment of impacts that are slightly offset with respect to the foam’s primary strength direction."
Mechanical Foams Rate Dependency Automotive High Speed Testing LS-DYNA Research Papers
July 27, 2015 | by Paul Du Bois | views 4274
"Heavy trucks have large masses and only small deformation zones. Because of this, they are loaded relatively severe in case of a crash. Under those conditions structural response is characterised not only by plastic deformation but also by failure in terms of cracks or fracture. Hence, failure prediction is essential for designing such parts. The following article describes the procedure of generating material models for failure prognosis of solid parts in the Commercial Vehicles Division at Daimler. Sheet metal parts are mostly discretised by shell elements. In this case the state of stress is characterized by hydrostatic pressure over von-Mises effective stress, the so-called triaxiality. For many real-life load cases which can be modeled by thin shells this ratio is between –2/3 and –2/3. Within this range the Gurson material model with the Tvergaard Needlemann addition leads to sufficiently accurate results. Furthermore, the Gurson material model allows considering the effect of element size, which amongst others is important for ductile materials. Most often however, in the case of solid parts the state of stress is more complex, which results in a triaxiality smaller than –1 or larger than 2/3. Gurson material models are usually validated based on shell meshes and tensile tests with flat bar specimen. If applied to solid parts, these models tend to underpredict failure . Thus, for solid parts the GURSON_JC material model is used. The Johnson Cook parameters are derived from an existing Gurson material model. Afterwards the material model is adapted to test results by modifying the load curve giving failure strain against triaxiality. This requires tensile tests"
Mechanical Metals Rate Dependency Yielding/Failure Analysis Automotive High Speed Testing LS-DYNA 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."
Mechanical Metals Yielding/Failure Analysis Aerospace and Defense High Speed Testing LS-DYNA Research Papers Validation
July 27, 2015 | by Paul Du Bois | views 3898
"Reliable prediction of the behavior 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 behavior properly are still not available in commercial finite element codes yet. In our paper, we present a new constitutive law for polymers which recovers important phenomena like necking, crazing, strain rate dependency, unloading behavior and damage. In particular, different yield surfaces in compression and tension and strain rate dependent failure, the latter with damage induced erosion, is taken into account. All relevant parameters are given directly in the input as load curves, i.e. time consuming parameter identification is not necessary. Moreover, the models by von Mises and Drucker-Prager are included in the description as special cases. With the present formulation, standard verification test can be simulated successfully: tensile and compression test, shear test and three point bending tests."
Mechanical Plastics Plasticity Rate Dependency Yielding/Failure Analysis Automotive High Speed Testing LS-DYNA Research Papers
July 27, 2015 | by Paul Du Bois | views 6326
"Reliable prediction of damage and failure in structural parts is a major challenge posed in engineering mechanics. Although solid material models predicting the deformation behaviour of a structure are increasingly available, reliable prediction of failure remains still open. With SAMP (a Semi-Analytical Model for Polymers), a general and flexible plasticity model is available in LS-DYNA since version 971. Although originally developed for plastics, the plasticity formulation in SAMP is generally applicable to materials that exhibit permanent deformation, such as thermoplastics, crushable foam, soil and metals. In this paper, we present a generalized damage and failure procedure that has been implemented in SAMP and will be available in LS-DYNA soon. In particular, important effects such as triaxiality, strain rate dependency, regularization and non-proportional loading are considered in SAMP. All required physical material parameters are provided in a user-friendly tabulated way. It is shown that our formalism includes many different damage and failure models as special cases, such as the well-known formulations by Johnson-Cook, Chaboche, Lemaitre and Gurson among others. "
Mechanical Plastics Plasticity Rate Dependency Yielding/Failure Analysis Automotive High Speed Testing LS-DYNA Research Papers
July 22, 2015 | by Paul Du Bois | views 4611
"Simulation of rubber-like materials is usually based on hyperelasticity. If strain-rate dependency has to be considered viscous dampers are added to the rheological model. A disadvantage of such a description is timeconsuming parameter identification associated with the damping constants. In this paper, a tabulated formulation is presented which allows fast generation of input data based on uniaxial static and dynamic tensile tests at different strain rates. Unloading, i.e. forming of a hysteresis, can also be modeled easily based on a damage formulation. We show the theoretical background and algorithmic setup of our model which has been implemented in the explicit solver LS-DYNA [1]-[3]. Apart from purely numerical examples, the validation of a soft and a hard rubber under loading and subsequent unloading at different strain rates is shown."
Mechanical Rubbers Hyperelastic Rate Dependency Yielding/Failure Analysis Automotive High Speed Testing LS-DYNA Research Papers
July 22, 2015 | by Paul Du Bois | views 4464
"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."
Mechanical Rate Dependency Yielding/Failure Analysis Automotive High Speed Testing LS-DYNA Research Papers
July 22, 2015 | by Paul Du Bois | views 4085
"During the past years polymer materials have gained enormous importance in the automotive industry. Especially their application for interior parts to help in passenger safety load cases and their use for bumper fascias in pedestrian safety load cases have driven the demand for much more realistic finite element simulations. For such applications the material model 187 (i.e. MAT_SAMP-1) in LS-DYNA® has been developed. In the present paper the authors show how the parameters for the rather general model may be adjusted to allow for the simulation of crazing effects during plastic loading. Crazing is usually understood as inelastic deformation that exhibits permanent volumetric deformations. Hence a material model that is intended to be applied for polymer components that show crazing effects during the experimental study, should be capable to produce the correct volumetric strains during the respective finite element simulation. The paper discusses the real world effect of crazing, the ideas to capture these effect in a numerical model and exemplifies the theoretical ideas with a real world structural component finite element model."
Mechanical Plastics Rate Dependency Automotive High Speed Testing LS-DYNA Research Papers
April 28, 2015 | by Paul Du Bois | views 4117
"The simulation of rubber materials is becoming increasingly important in automotive crashworthiness simulations. Although highly sophisticated material laws are available in LS-DYNA to model rubber parts, the determination of material properties can be non-trivial and time consuming. In many applications, the rubber component is mainly loaded uniaxially at rather high strain rates. In this paper a simplified material model for rubber is presented allowing for a fast generation of input data based on uniaxial static and dynamic test data."
Mechanical Rubbers Hyperelastic Rate Dependency Automotive High Speed Testing LS-DYNA Research Papers
October 28, 2014 | by DatapointLabs | views 4833
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.
High Speed Testing Nonlinear Material Models Structural Analysis ANSYS Presentations Validation
October 08, 2014 | by DatapointLabs | views 4497
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.
Plastics Rubbers Foams Metals High Speed Testing Injection Molding Nonlinear Material Models Structural Analysis LS-DYNA Composites Presentations
September 21, 2014 | by DatapointLabs | views 4279
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.
Plastics High Speed Testing Nonlinear Material Models ANSYS Presentations
May 20, 2014 | by Datapoint Newsletters | views 5201
Verification and Validation Are Focus of Technical Presentations at CAE Events, New Multi-CAE TestPaks® Deliver Data for Injection Molding and Crash Simulations,
May 13, 2014 | by DatapointLabs | views 5171
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.
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
May 08, 2011 | by DatapointLabs | views 4614
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.
Plastics Rubbers Foams Metals High Speed Testing Nonlinear Material Models Structural Analysis Abaqus Composites SIMULIA Presentations
March 10, 2011 | by DatapointLabs | views 4301
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.
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 4004
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
Blow Molding Extrusion High Speed Testing Injection Molding Nonlinear Material Models Structural Analysis DIGIMAT Presentations
May 26, 2010 | by DatapointLabs | views 4122
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.
Plastics Automotive High Speed Testing Nonlinear Material Models Structural Analysis LS-DYNA Abaqus ANSYS PAM-CRASH Altair RADIOSS Presentations
May 11, 2009 | by DatapointLabs | views 5383
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.
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
May 08, 2009 | by Datapoint Newsletters | views 4580
DatapointLabs Featured in Technical Conferences.
Plastics Rubbers Foams Hyperelastic High Speed Testing Nonlinear Material Models LS-DYNA Abaqus Newsletters
April 13, 2009 | by DatapointLabs | views 4566
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.
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
July 17, 2008 | by DatapointLabs | views 4253
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.
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
November 27, 2007 | by DatapointLabs | views 4696
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.
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
May 19, 2006 | by DatapointLabs | views 4205
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.
April 28, 2005 | by DatapointLabs | views 4961
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
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
October 22, 1997 | by DatapointLabs | views 4912
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...
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
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