Rate-Dependent Constitutive Modeling of Polymer Subjected to Dynamic Loading

2012 ◽  
Vol 185 ◽  
pp. 119-121
Author(s):  
Jian Ming Yuan ◽  
Jan Ma ◽  
Geoffrey E.B. Tan ◽  
Jian Fei Liu
Keyword(s):  
Test Data ◽  
Constitutive Modeling ◽  
Dynamic Compression ◽  
Fem Simulation ◽  
Material Model ◽  
Strain Rates ◽  
Compression Tests ◽  
Material Models ◽  
Rate Dependent ◽  
Tension Tests

This paper proposes an effective and systematical method to obtain reliable rate-dependent material models used in FEM simulation for polymers. Compressive stress-strain curves of two types of polymer are obtained at different strain rates. Rate-dependent elastic-plastic models are applied to describe the observed rate-dependent behaviors, whereby the input data of material model are determined from the test data obtained. Verification of the material models is proposed via comparing FEM simulation with test data of quasi-static tension tests and dynamic compression tests of different strain rates.

Modeling of the Rate Responsive Behavior of Elastomer Foam Materials

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Feixia Pan
Keyword(s):  
Finite Element ◽  
Constitutive Model ◽  
Test Data ◽  
Experimental Test ◽  
Strain Rates ◽  
Foam Material ◽  
Material Models ◽  
Rate Dependent ◽  
Responsive Behavior ◽  
Rate Responsive

Elastomer foam materials are shock absorbers that have been extensively used in applications of electronic packaging. Finite element modeling simulation plays an important role in helping the designers determine the best elastomer foam material and the best structure of a shock absorber. Elastomer foam materials have very complicated material behaviors. The prediction of the rate responsive behavior is one of the most interesting topics in elastomer material modeling. The focus of this article is to present a unique method for deriving the rate dependent constitutive model of an elastomer foam based on the extension of the Cowper and Symond law and the curve fitting on experimental test data. The research on rate dependent material models and the material models available in commercially available finite element analysis software have been reviewed. Test data collection at various strain rates has been discussed. Two steps of curve fitting on experimental test data are used to retrieve analytical expression of the constitutive model. The performance of the constitutive model for a foam material has been illustrated and shown to be quite good. This method is easy to understand and the simple formulation of the constitutive model is very suitable for applications in numerical simulation. The constitutive model could be used to predict the stress-strain curves of a foam material at any strain rate, especially at the intermediate strain rates, which are the most difficult to collect so far. In addition, this model could be readily integrated with the hyperelastic material models to more efficiently evaluate the mechanical behavior of an elastomer foam material. The model could potentially be implemented in commercially available software such as ABAQUS and LS-DYNA. The method presented is also useful in deriving constitutive models of rubberlike elastomer materials.

Mechanical Testing and Material Modeling of Thermoplastics: Polycarbonate, Polypropylene and Acrylonitrile-Butadiene-Styrene

2008 ◽  
Vol 1130 ◽  
Author(s):  
Jean-Luc Bouvard ◽  
Hayley Brown ◽  
Esteban Marin ◽  
Paul Wang ◽  
Mark Horstemeyer
Keyword(s):  
Mechanical Response ◽  
Acrylonitrile Butadiene Styrene ◽  
Material Model ◽  
Strain Rates ◽  
Ongoing Research ◽  
Rate Dependent ◽  
Tension Tests ◽  
Model Predictions ◽  
Good Agreement ◽  
Butadiene Styrene

AbstractThe work presents some results of an ongoing research program aimed at building a material database and material models for specific types of polymers. Results for three thermoplastics are the focus of the present article: polycarbonate, polypropylene, and acrylonitrile-butadiene-styrene. Uniaxial compression / tension tests at room temperature and different strain rates have been performed to characterize their mechanical response. A rate-dependent material model has been developed and implemented in a finite element code to predict such mechanical behavior. The model predictions have shown good agreement with the tests results.

Influence of strain rate, temperature and fatigue on the radial compression behaviour of Norway spruce

Holzforschung ◽  
2017 ◽  
Vol 71 (6) ◽  
pp. 505-514 ◽  
Author(s):  
Carolina Moilanen ◽  
Tomas Björkqvist ◽  
Markus Ovaska ◽  
Juha Koivisto ◽  
Amandine Miksic ◽  
...  
Keyword(s):  
Strain Rate ◽  
Linear Model ◽  
Norway Spruce ◽  
Material Model ◽  
Radial Compression ◽  
Compression Tests ◽  
Static Compression ◽  
Rate Dependent ◽  
Compression Model ◽  
Wood Compression

Abstract A dynamic elastoplastic compression model of Norway spruce for virtual computer optimization of mechanical pulping processes was developed. The empirical wood behaviour was fitted to a Voigt-Kelvin material model, which is based on quasi static compression and high strain rate compression tests (QSCT and HSRT, respectively) of wood at room temperature and at high temperature (80–100°C). The effect of wood fatigue was also included in the model. Wood compression stress-strain curves have an initial linear elastic region, a plateau region and a densification region. The latter was not reached in the HSRT. Earlywood (EW) and latewood (LW) contributions were considered separately. In the radial direction, the wood structure is layered and can well be modelled by serially loaded layers. The EW model was a two part linear model and the LW was modelled by a linear model, both with a strain rate dependent term. The model corresponds well to the measured values and this is the first compression model for EW and LW that is based on experiments under conditions close to those used in mechanical pulping.

A Microstructure-Level Material Model for Simulating the Machining of Carbon Nanotube Reinforced Polymer Composites

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Ashutosh Dikshit ◽  
Johnson Samuel ◽  
Richard E. DeVor ◽  
Shiv G. Kapoor
Keyword(s):  
Carbon Nanotube ◽  
Weight Fraction ◽  
Material Model ◽  
Material Behavior ◽  
Compression Tests ◽  
Linear Elastic ◽  
Rate Dependent ◽  
Wide Range ◽  
Parametrization Scheme ◽  
Fraction Length

A continuum-based microstructure-level material model for simulation of polycarbonate carbon nanotube (CNT) composite machining has been developed wherein polycarbonate and CNT phases are modeled separately. A parametrization scheme is developed to characterize the microstructure of composites having different loadings of carbon nanotubes. The Mulliken and Boyce constitutive model [2006, “Mechanics of the Rate Dependent Elastic Plastic Deformation of Glassy Polymers from Low to High Strair Rates,” Int. J. Solids Struct., 43(5), pp. 1331–1356] for polycarbonate has been modified and implemented to capture thermal effects. The CNT phase is modeled as a linear elastic material. Dynamic mechanical analyzer tests are conducted on the polycarbonate phase to capture the changes in material behavior with temperature and strain rate. Compression tests are performed over a wide range of strain rates for model validation. The model predictions for yield stress are seen to be within 10% of the experimental results for all the materials tested. The model is used to study the effect of weight fraction, length, and orientation of CNTs on the mechanical behavior of the composites.

Input Data Determination for Large Strain Simulations

2015 ◽  
Vol 751 ◽  
pp. 124-130
Author(s):  
Jan Džugan ◽  
Martina Maresova ◽  
Jan Nachazel
Keyword(s):  
Numerical Simulations ◽  
Input Data ◽  
Large Strain ◽  
Fem Simulation ◽  
Material Behavior ◽  
Production Costs ◽  
Image Correlation ◽  
Compression Tests ◽  
Material Models ◽  
Strain Measurements

Numerical simulations are widely used for forming processes optimizations nowadays. They significantly contribute to improvement of forgings quality and production costs reduction. The crucial points of the numerical simulations are material input data and implemented material models. The paper is dealing with overview of methods for the input data measurement. There are discussed tests with various options of strain measurements as well as modifications of compression tests. Part of the paper is dealing with 3D strain measurements by Digital Image Correlation (DIC) enabling local strains measurements. DIC enables direct comparison of strains experimentally measured and strains obtained by numerical simulations, which is going to be presented. Finally, possibilities of complex material description considering plastic damage are presented. The last approach is the most accurate providing the most information on material behavior for FEM simulation, the procedure includes measurements on samples of various geometries with various stress strain conditions. Examples of sample sets for these measurements are shown here together with material models describing multiaxial plastic flow and damage.

Asymmetric Yield Locus Evolution for HCP Materials: A Continuum Constitutive Modeling Approach

2013 ◽  
Vol 554-557 ◽  
pp. 1184-1188
Author(s):  
Dariush Ghaffari Tari ◽  
Michael J. Worswick ◽  
Usman Ali
Keyword(s):  
Constitutive Modeling ◽  
Material Model ◽  
Anisotropic Hardening ◽  
Material Models ◽  
Compression Behavior ◽  
Modified Model ◽  
Hcp Materials ◽  
Asymmetry Parameters ◽  
Deviatoric Stress Tensor ◽  
Hexagonal Closed Packed

A continuum-based plasticity approach is considered to model the anisotropic hardening response of hexagonal closed packed (hcp) materials. A Cazacu-Plunkett-Barlat (CPB06) yield surface is modified to create anisotropic hardening in terms of the accumulated plastic strain. The anisotropy and asymmetry parameters are replaced with saturation-type functions and the new modified model is then optimized globally to fit the material response. Furthermore, the effect of the number of linear stress transformations performed on the deviatoric stress tensor is investigated on the capability of the model to capture the response from the experiments. By increasing the number of stress transformations, more flexibility is obtained. However, increasing the number of stress transformations increases the arithmetic calculations involved in the material model. The proposed approach is an effective and time efficient method to create material models with complex evolving tension/compression behavior.

Numerical Simulation of Small-Scale Explosion in Dry Sand

2013 ◽  
Vol 705 ◽  
pp. 110-114
Author(s):  
Yu Qing Ding ◽  
Wen Hui Tang ◽  
Xian Wen Ran ◽  
Xin Xu
Keyword(s):  
Numerical Simulation ◽  
Test Data ◽  
Detonation Product ◽  
Material Model ◽  
Small Scale ◽  
Two Dimensional ◽  
Material Models ◽  
Simulation Results ◽  
Dry Sand ◽  
Sand Material

Numerical simulation of small-scale explosion in dry sand using two sand material models including the Sand model and the LA model were carried out in the present study. Three cases were considered which the depths of burial (DOB) of the explosive C4 charge were 0, 30 mm and 80 mm, respectively. The time arrival of the blast-wave front and the maximum overpressure of fixed measuring locations were studied using a two dimensional axisymmetric model in hydrocode ANSYS/AUTODYN. Furthermore, the crater diameters and the heights of detonation product cloud respect to the time were also studied by comparing with the test data. The simulation results indicate that the both sand material models were hardly predict the test data exactly which proves that the sand properties and the material model should be more carefully studied and defined.

Thermal Deformation Behavior and Processing Map of Al-Mg-Er Alloy

2018 ◽  
Vol 913 ◽  
pp. 30-36
Author(s):  
Ran Liu ◽  
Hui Huang ◽  
Ya Liu ◽  
Li Rong
Keyword(s):  
Flow Stress ◽  
Deformation Behavior ◽  
Deformation Temperature ◽  
Material Model ◽  
Instability Criterion ◽  
Strain Rates ◽  
Processing Maps ◽  
Hot Workability ◽  
Compression Tests ◽  
Dynamic Material Model

To study the hot deformation behavior of Al-Mg-Er alloy, hot compression tests were conducted on a Gleeble-1500D thermal simulator at the temperature range of 200-500°C with the strain rates from 0.001 to 10s-1. With the increase in the deformation temperature and the decrease in strain rates, the flow stress of the Al-Mg-Er alloy decreased. Processing maps were constructed to study on hot workability characteristics. The results showed that the flow stress curves exhibited the typical dynamic recrystallization characteristics and the stress decreased with the increase of deformation temperature and the decrease of strain rate. Moreover, the processing maps were established on the basis of dynamic material model and Prasad’s instability criterion.

Designing Hot Working Processes of Nickel Base Superalloys Using FEM Simulation

2001 ◽  
Author(s):  
R. Kopp ◽  
M. Tschirnich ◽  
M. Wolske ◽  
J. Klöwer
Keyword(s):  
Testing Machine ◽  
Fem Simulation ◽  
Material Model ◽  
Hydraulic Testing ◽  
Compression Tests ◽  
Finite Element Program ◽  
Real Process ◽  
Forming Temperature ◽  
Element Program ◽  
Nickel Base

Knowledge of correct flow stress curves of Ni-based alloys at high temperatures is of essential importance for reliable plasto-mechanical simulations in materials processing and for an effective planning and designing of industrial hot forming schedules like hot rolling or forging. The experiments are performed on a computer controlled servo-hydraulic testing machine at IBF (Institute of Metal Forming). To avoid an inhomogeneous deformation due to the influence of friction and initial microstructure, a suitable specimen geometry and lubricant is used and a thermal treatment before testing has to provide a microstructure, similar to the structure of the material in the real process. The compression tests are performed within a furnace, which keeps sample, tools and surrounding atmosphere at the defined forming temperature. The uniaxial compressions were carried out in the range of strain rates between 0.001 and 50 s−1 and temperatures between 950 and 1280°C. Furthermore two-stage step tests are carried out to derive the work hardening and softening behaviour as well as the recrystallisation kinetics of the selected Ni-based alloys. At the end of this work a material model is adapted by the previously determined material data. This model is integrated into the Finite Element program LARSTRAN/SHAPE to calculate a forging process of the material Alloy 617.

scholarly journals Experimental Tests, FEM Constitutive Modeling and Validation of PLGA Bioresorbable Polymer for Stent Applications

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2003
Author(s):  
Jakub Bukala ◽  
Piotr P. Buszman ◽  
Jerzy Małachowski ◽  
Lukasz Mazurkiewicz ◽  
Kamil Sybilski
Keyword(s):  
Constitutive Modeling ◽  
Experimental Tests ◽  
Material Model ◽  
Coronary Intervention ◽  
Compression Tests ◽  
Rate Dependency ◽  
Type Specimens ◽  
Modeling Methodology ◽  
Bioresorbable Polymer ◽  
Modeling Strategy

The use of bioresorbable polymers such as poly(lactic-co-glycolic acid) (PLGA) in coronary stents can hypothetically reduce the risk of complications (e.g., restenosis, thrombosis) after percutaneous coronary intervention. However, there is a need for a constitutive modeling strategy that combines the simplicity of implementation with strain rate dependency. Here, a constitutive modeling methodology for PLGA comprising numerical simulation using a finite element method is presented. First, the methodology and results of PLGA experimental tests are presented, with a focus on tension tests of tubular-type specimens with different strain rates. Subsequently, the constitutive modeling methodology is proposed and described. Material model constants are determined based on the results of the experimental tests. Finally, the developed methodology is validated by experimental and numerical comparisons of stent free compression tests with various compression speeds. The validation results show acceptable correlation in terms of both quality and quantity. The proposed and validated constitutive modeling approach for the bioresorbable polymer provides a useful tool for the design and evaluation of bioresorbable stents.

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