scholarly journals Behavior of the Abaqus CDP model in simple stress states

2019 ◽  
Vol 52 (2) ◽  
pp. 87-113
Author(s):  
Alexis Fedoroff ◽  
Kim Calonius ◽  
Juha Kuutti
Keyword(s):  
Pure Shear ◽  
Material Model ◽  
Sensitivity Study ◽  
Stress States ◽  
Tension State ◽  
Impact Simulations ◽  
Parameter Values ◽  
Shear State ◽  
Element Removal ◽  
Simple Stress

In order to use the Abaqus Concrete Damaged Plasticity (CDP) material model in simulations of reinforced concrete structures, one has to understand the effect of various parameters of the material model. Although most of the material parameters can be determined from standard concrete tests, some parameters need more advanced tests to be determined. In impact simulations, one often has only limited material data available, and it makes therefore sense to study the parameter sensitivity of the material model in order to fix realistic parameter values. In this paper, the sensitivity of the simulation response with respect to two modelparameters is studied: the dilation angle and the tensile to compressive meridian ratio. The sensitivity study is performed in three simple but representative stress states: the uniaxial tension state, the confined uniaxial compressive state and the pure shear state. Finally, it is discussed how these simple stress states relate to the element removal criteria, which is necessary in simulations involving fragmentation.

Determination of a Rubber-Like Material Model as an Inverse Problem

2011 ◽  
Vol 70 ◽  
pp. 225-230 ◽  
Author(s):  
Agnieszka Derewonko ◽  
Andrzej Kiczko
Keyword(s):  
Selection Process ◽  
Axial Stress ◽  
Constitutive Models ◽  
Material Model ◽  
Polyester Fabric ◽  
Point Of View ◽  
Air Cushion ◽  
Ill Conditioning ◽  
Stress States

The purpose of this paper is to describe the selection process of a rubber-like material model useful for simulation behaviour of an inflatable air cushion under multi-axial stress states. The air cushion is a part of a single segment of a pontoon bridge. The air cushion is constructed of a polyester fabric reinforced membrane such as Hypalon®. From a numerical point of view such a composite type poses a challenge since numerical ill-conditioning can occur due to stiffness differences between rubber and fabric. Due to the analysis of the large deformation dynamic response of the structure, the LS-Dyna code is used. Since LS-Dyna contains more than two-hundred constitutive models the inverse method is used to determine parameters characterizing the material on the base of results of the experimental test.

Prediction of Cutting Force in Bone Cutting Using Finite Element Analysis

2021 ◽  
Author(s):  
Varatharajan Prasannavenkadesan ◽  
Ponnusamy Pandithevan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cutting Force ◽  
Material Model ◽  
Tensile Tests ◽  
Bovine Bone ◽  
Element Analysis ◽  
Cutting Processes ◽  
Parameter Values ◽  
First Time

Abstract In orthopedic surgery, bone cutting is an indispensable procedure followed by the surgeons to treat the fractured and fragmented bones. Because of the unsuitable parameter values used in the cutting processes, micro crack, fragmentation, and thermal osteonecrosis of bone are observed. Therefore, prediction of suitable cutting force is essential to subtract the bone without any adverse effect. In this study, the Cowper-Symonds model for bovine bone was developed for the first time. Then the developed model was coupled with the finite element analysis to predict the cutting force. To determine the model constants, tensile tests with different strain rates (10−5/s, 10−4/s, 10−3/s, and 1/s) were conducted on the cortical bone specimens. The developed material model was implemented in the bone cutting simulation and validated with the experiments.

Sensitivity Study of Material Input Data on FE Forming Results for Wrinkling and Shearing of Fiber Reinforced Thermoplastic Parts

2019 ◽  
Vol 809 ◽  
pp. 500-505
Author(s):  
Bernd Engel ◽  
Jasmin Graef
Keyword(s):  
Input Data ◽  
Test Procedure ◽  
Material Model ◽  
Sensitivity Study ◽  
Bending Test ◽  
Fiber Reinforced ◽  
Forming Process ◽  
Bias Extension ◽  
Reinforced Thermoplastics ◽  
Material Input

This work presents the analysis of the influence of several material input data to the FE results of the forming process of fiber reinforced thermoplastics within a sensitivity study. The *Fabric material model of Abaqus/Explicit is used for the description of the shear, tensile and compression behavior. It is a test-data based model. The bending behavior will be modeled with beam elements. The interaction between input data will be analyzed and its influence onto the FE forming results and FE analysis of material tests like bias-extension-test, compression and bending test with focus on interactions of input data and test procedure itself.

Effect of Critical Void Volume Fraction fF on Results of Ductile Fracture Simulation for S235JR Steel under Multi-Axial Stress States

2014 ◽  
Vol 598 ◽  
pp. 113-118 ◽  
Author(s):  
Paweł Grzegorz Kossakowski ◽  
Wiktor Wciślik
Keyword(s):  
Volume Fraction ◽  
Axial Stress ◽  
Material Model ◽  
Model Parameters ◽  
Material Microstructure ◽  
Fracture Simulation ◽  
Critical Volume Fraction ◽  
Stress States ◽  
The Impact ◽  
Critical Void

The article describes an example of the GTN material model parameters determination and application. The main objective of the study was to determine experimentally the value of the critical volume fraction of voids fFfor S235JR steel and to assess the impact of this parameter on the numerical force-elongation curve under the multi-axial stress state. Value of fFwas obtained by the quantitative analysis of the material microstructure at fracture surfaces. For a sake of comparison, two other values of fF, described in the literature, were also used in numerical simulations.

scholarly journals Material Characterization for FEM Simulation of Sheet Metal Stamping Processes

2014 ◽  
Vol 6 ◽  
pp. 167147 ◽  
Author(s):  
Alejandro Quesada ◽  
Antonio Gauchia ◽  
Carolina Álvarez-Caldas ◽  
José Luis San Román
Keyword(s):  
Sheet Metal ◽  
Manufacturing Industry ◽  
Fem Simulation ◽  
Main Tool ◽  
Material Model ◽  
Experimental Results ◽  
Simulation Tools ◽  
Sheet Metal Parts ◽  
Simulation Results ◽  
Parameter Values

Sheet metal forming is an important technology in manufacturing, especially in the automotive industry. Today, engineering simulation tools based on the finite elements method are employed regularly in the design of stamping dies for sheet metal parts. However, a bad material model choice or the use of nonaccurate enough parameters can lead to imprecise simulation results. This work uses ANSYS LS-DYNA software to analyze several material models and the influence of their parameter values in FEM simulation results. The main tool to solve these problems is an application designed to assist die stamp designers. The program allows a procedure to be defined to obtain the values of the properties of an unknown material, which combines finite element simulations with real experimental results. Results obtained for the simulation of a real automotive part are analyzed and compared with the real experimental results. Parameters involved in each material model have been identified, and their influence in final results has been quantified. This is very useful to fit material properties in other simulations. This paper fulfils an identified need in the manufacturing industry. In fact, the proposed application is currently being used by a manufacturer of automotive components.

Uplift and Mantle Thickness: A Sensitivity Study

2007 ◽  
Vol 25 (4) ◽  
pp. 273-299
Author(s):  
I. Lerche ◽  
K. Reicherter
Keyword(s):  
Heat Flux ◽  
Input Parameter ◽  
Sensitivity Study ◽  
Surface Heat ◽  
Water Density ◽  
Relative Contribution ◽  
Input Variables ◽  
Crustal Density ◽  
Parameter Values ◽  
Mantle Thickness

This paper derives an inverse set of equations for equilibrium situations to discuss the resolution and sensitivity of models used to describe tectonic uplift and thermal heat flux. The sensitivity of results to variations in single parameters away from a described set of canonical values is given first. This sensitivity study is followed by a detailed treatment describing the probabilities of obtaining mantle thickness, surface heat flux, thermal expansion coefficient, base crustal heat flux, and Moho temperature at or above particular values as the water density, crustal density, asthenospheric density, uplift, crustal thickness, average lithospheric density, base lithospheric temperature, and water depth to the free asthenosphere marker are all allowed to vary simultaneously around their canonical values. In addition, a relative contribution plot for each of the five output variables identifies which of the eight input variables is causing the greatest contribution to the uncertainty. In this way one can identify which variables need to have their ranges of uncertainty narrowed in order to be more precise about the chances of obtaining particular values for the five outputs. A skewness estimate also is given that enables one to determine the most likely directions one should expect improvement to occur with a probability plot of obtaining particular values, or higher, for each of the output variables. Numerical illustrations show how one goes about performing the quantitative assessments and also show how the inverse procedure allows one to be more definitive concerning the five output values, and their ranges of uncertainty, because of uncertainties in the eight input parameter values.

scholarly journals Characterization of polystyrene under shear deformation using Molecular Dynamics

2021 ◽  
Author(s):  
Maximilian Ries ◽  
Paul Steinmann ◽  
Sebastian Pfaller
Keyword(s):  
Molecular Dynamics ◽  
Shear Deformation ◽  
Pure Shear ◽  
Material Model ◽  
Md Simulations ◽  
Constitutive Law ◽  
Coupling Scheme ◽  
Suitable Material ◽  
Continuum Description ◽  
The Continuum

Nano-filled polymers are becoming more and more important to meet the continuously growing requirements of modern engineering problems. The investigation of these composite materials at the molecular level, however, is either prohibitively expensive or just impossible. Multiscale approaches offer an elegant way to analyze such nanocomposites by significantly reducing computational costs compared to fully molecular simulations.When coupling different time and length scales, however, it is in particular important to ensure that the same material description is applied at each level of resolution.The Capriccio method, for instance, couples a particle domain modeled with molecular dynamics (MD) with a finite element based continuum description and has been used i.a. to investigate the effects of nano-sized silica additives embedded in atactic polystyrene (PS). However, a simple hyperelastic constitutive law is used so far for the continuum description which is not capable to fully match the behavior of the particle domain. To overcome this issue and to enable further optimization of the coupling scheme, the material model used for the continuum should be derived directly from pure MD simulations under thermodynamic conditions identical to those used by the Capriccio method.To this end, we analyze the material response of pure PS under uniaxial deformation using strain-controlled MD simulations. Analogously, we perform simulations under pure shear deformation to obtain a comprehensive understanding of the material behavior.As a result, the present PS shows viscoelastic characteristics for small strains, whereas viscoplasticity is observed for larger deformations. The insights gained and data generated are used to select a suitable material model whose parameters have to be identified in a subsequent parameter optimization.

A Study on the Material Modeling of a Robot Polyurethane Stopper

2009 ◽  
Author(s):  
Kyukwon Bang ◽  
Taewung Kim ◽  
Hyun-Yong Jeong
Keyword(s):  
Finite Element ◽  
Shear Test ◽  
Pure Shear ◽  
Material Model ◽  
Tension Test ◽  
Material Behavior ◽  
Prony Series ◽  
Material Constants ◽  
Torsion Vibration ◽  
Element Simulation

Polyurethane stoppers are used to protect heavy parts from damage in case of an unpredicted impact between parts in a robot. In order to evaluate the performance of a polyurethane stopper during impact, it was necessary to model the material behavior. Thus, the compression test, the tension test, the pure shear test, the torsion vibration test were conducted, and the hyperelastic material constants and viscoelastic material constants (Prony series parameters) were determined. Finite element simulations for the tests were conducted to check whether the material model adequately represented the material behavior. In addition, a finite element simulation for an impact between a part of a robot and a stopper was conducted to evaluate the performance of a stopper.

Mechanical Properties of the Porcine Coronary Artery

2009 ◽  
Author(s):  
Chantal N. van den Broek ◽  
Arjen van der Horst ◽  
Marcel C. N. Rutten ◽  
Frans N. van de Vosse
Keyword(s):  
Mechanical Properties ◽  
Coronary Artery ◽  
Vascular Function ◽  
Arterial Wall ◽  
Material Model ◽  
Porcine Coronary Artery ◽  
Balloon Catheters ◽  
General Parameter ◽  
Fiber Reinforced Material ◽  
Parameter Values

Knowledge of the mechanical properties of arteries is important to understand vascular function during disease and the effect of interventions, such as PTCA treatment. A mechanical model of the vascular tree would facilitate the improvement of (balloon-)catheters and stents. The aim of this research is to propose general parameter values for the fiber-reinforced material model as proposed by Driessen et al. (2005) that can describe the arterial wall behavior of the porcine left anterior descending coronary artery (LAD, fig. 1a) at physiological axial stretch.

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