Assessment of Failure Modeling With Thinning Strain Criterion in LS-DYNA

2003 ◽  
Author(s):  
Ching-Shan Cheng
Keyword(s):  
Failure Criterion ◽  
Material Model ◽  
Failure Criteria ◽  
Material Failure ◽  
Strain Criterion ◽  
Element Analysis ◽  
Material Models ◽  
Ductile Materials ◽  
Failure Modeling ◽  
Nonlinear Nature

Element deletion based on various failure criteria has been implemented in commercial finite element analysis packages, e.g. LS-DYNA. However, due to the localized and nonlinear nature of the material failure, especially for the ductile materials, a good failure criterion needs to be robust for different mesh definitions and loading conditions. In the present work, the material model with enhanced failure criterion in LS-DYNA, material type 123 (MAT123), is investigated. The equations for determining the parameter of the thinning strain failure criterion are derived based on the assumptions that Yeh et al. [7] proposed. Simulations of different tests using MAT123 with the thinning strain at failure calculated show better correlation with the experimental results than the other material models examined.

Improving failure sub-models in an orthotropic plasticity-based material model

2020 ◽  
pp. 002199832098265
Author(s):  
Loukham Shyamsunder ◽  
Bilal Khaled ◽  
Subramaniam D Rajan ◽  
Gunther Blankenhorn
Keyword(s):  
Finite Element ◽  
Failure Criterion ◽  
High Speed ◽  
Simulation Models ◽  
Material Model ◽  
Failure Criteria ◽  
Element Analysis ◽  
Explicit Finite Element ◽  
Explicit Finite Element Analysis ◽  
Static Tensile

Theoretical details of two failure criteria implemented in an orthotropic plasticity model are presented. Improvements to the well-known Puck Failure criterion and a recently developed Generalized Tabulated Failure criterion are used to illustrate how to link a failure sub-model to existing deformation and damage sub-models in the context of explicit finite element analysis. These models are implemented in LS-DYNA, a commercial transient dynamic finite element code. Two validation tests are used to evaluate the failure sub-model implementation and improvements - a stacked-ply test carried out at room temperature under quasi-static tensile and compressive loadings, and a high-speed, projectile impact test where there is significant damage and material failure of the impacted panel. Results indicate that developed procedures and improvements provide the analyst with a reasonable and systematic approach to building predictive impact simulation models.

Strain-Based Failure Criteria for Sharp Part-Wall Defects in Pipelines

1998 ◽  
Author(s):  
Aaron S. Dinovitzer ◽  
Brian A. Graville ◽  
Alan G. Glover
Keyword(s):  
Finite Element ◽  
Failure Criterion ◽  
Local Strain ◽  
Failure Criteria ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Element Analysis ◽  
Acceptance Criterion ◽  
Linear Finite Element ◽  
Non Linear

Failure criteria in current engineering critical assessment procedures for defects in pipelines and welds are stress-based. For example, failure is presumed to occur when the net section average stress reaches some arbitrary flow stress. These approaches are unrealistic for defects of limited length where loading of the net section (ligament) is essentially strain controlled. In order to improve upon this, the authors developed a strain-based failure criterion for part wall pipe defects in terms of the maximum ligament plastic extension. While this criterion[l] provided a basis for assessing the criticality of blunt defects, with respect to plastic collapse, it did not address sharp or planar defects which promote fracture. As a defect becomes sharper, failure is determined more by local strain at the defect tip which is typically characterized by the crack tip opening displacement (CTOD). This paper describes the development of a sharp/planar defect strain-based failure criterion which relates the maximum ligament extension to the critical CTOD of the material. Two and three dimensional non-linear finite element analyses are used to determine local root extensions of circumferential defects which can be related to the loading, defect and pipe dimensions. The root extensions are calibrated to standard CTOD measurements through non-linear finite element analysis. The failure criterion development process considers various defect lengths, material work hardening rates and material models. The failure criterion is compared with analytical and experimental data to demonstrate its predictive capability. The end result of this work is the development of an alternative acceptance criterion for sharp weld defects permitting more effective repair decisions to be made based on a more uniform level of reliability.

A Teaching Note on Failure Criteria and Failure Surfaces for Ductile and Brittle Materials

1994 ◽  
Vol 22 (1) ◽  
pp. 1-13 ◽  
Author(s):  
G. S. Schajer
Keyword(s):  
Isotropic Material ◽  
Three Dimensional ◽  
Brittle Materials ◽  
Failure Criteria ◽  
Material Failure ◽  
Stress Space ◽  
Ductile Materials ◽  
Basic Concepts ◽  
Multiaxial Loadings

This note discusses some basic concepts underlying isotropic material failure criteria under multiaxial loadings. It also describes the shapes and features of the associated failure surfaces in three-dimensional stress space. Failure criteria for ductile materials are first reviewed. They are then generalized so that they may also be applied to brittle materials. The relationships among the various failure criteria, the shapes and characteristics of the associated failure surfaces, and the special features of physically acceptable isotropic failure criteria are then considered.

Methods for Theoretical Assessment of Delamination Risks in Electronic Packaging

2017 ◽  
Author(s):  
Torsten Hauck ◽  
Ilko Schmadlak ◽  
Nishant Lakhera ◽  
Sandeep Shantaram ◽  
David Samet ◽  
...  
Keyword(s):  
Fracture Mechanics ◽  
Electronic Packaging ◽  
Bulk Material ◽  
Material Model ◽  
Simulation Method ◽  
Critical Energy ◽  
Failure Criteria ◽  
Electronic Packages ◽  
Element Analysis ◽  
Advantages And Disadvantages

Fracture mechanics is an essential field of study towards the improvement and development of electronic packages. In combination with modern simulation method such as finite element analysis (FEA), fracture mechanics is widely used and appreciated in the industry. Many different approaches have been developed to calculate the fracture parameters for interfaces or bulk material under given loads in order to compare them against previously measured failure criteria. While many publications are available that have described the different simulation approaches in detail or compare the different fracture test methods, there have been few comparisons of these simulation approaches with respect to their use in research and development of electronic packages. The objective of this work is to compare different delamination modeling methodologies and their applications for electronic packaging. The work highlights the differences in theory behind each approach as well as the differences in their practical use to predict delamination or asses a fracture risk in electronic packages. The intention was to use commercially available FE-codes in conjunction with a well-defined set of adhesion strength tests. During this work, energy based fracture criteria were applied by means of the virtual crack closure technique (VCCT), the J-integral and the cohesive zone material model (CZM) methods. These methodologies are most commonly used but can differ significantly from each other as will be shown in this comparison. To demonstrate the use of these techniques, copper lead frame to epoxy mold compound (EMC) delamination was assessed, representing a very common packaging failure mode. Critical energy release rates were measured on multiple Copper-EMC test specimens under varying load phase angles. ANSYS was used to build mechanical simulation models of a selected device. Existing post processing procedures were applied to assess delamination risk based on above mentioned techniques. The simulation study considers realistic monotonic loading conditions and results will also be compared to existing failure analysis images for demonstration and validation purpose. As an outcome, the paper will include a ranking of the approaches as well as a summary of advantages and disadvantages, based method and accuracy. An outlook on future developments such as fatigue or aging phenomena will finish the work.

scholarly journals Analysis of Impact Energy to Fracture Unnotched Charpy Specimens Made From Railroad Tank Car Steel

2007 ◽  
Author(s):  
H. Yu ◽  
D. Y. Jeong ◽  
J. E. Gordon ◽  
Y. H. Tang
Keyword(s):  
Test Data ◽  
Impact Energy ◽  
Stress Triaxiality ◽  
Fracture Initiation ◽  
Equivalent Strain ◽  
Strain Criterion ◽  
Element Analysis ◽  
Damage And Failure ◽  
Failure Modeling ◽  
The Impact

This paper describes a nonlinear finite element analysis (FEA) framework that examines the impact energy to fracture unnotched Charpy specimens by an oversized, nonstandard pendulum impactor called the Bulk Fracture Charpy Machine (BFCM). The specimens are made from railroad tank car steel, have different thicknesses and interact with impact tups with different sharpness. The FEA employs a Ramberg-Osgood equation for plastic deformations. Progressive damage and failure modeling is applied to predict initiation and evolution of fracture and ultimate material failure. Two types of fracture initiation criterion, i.e., the constant equivalent strain criterion and the stress triaxiality dependent equivalent strain criterion, are compared in material modeling. The impact energy needed to fracture a BFCM specimen is calculated from the FEA. Comparisons with the test data show that the FEA results obtained using the stress triaxiality dependent fracture criterion are in excellent agreement with the BFCM test data.

scholarly journals Computational consistency of the material models and boundary conditions for finite element analyses on cantilever beams

2018 ◽  
Vol 10 (6) ◽  
pp. 168781401878002 ◽  
Author(s):  
Wei-chen Lee ◽  
Chen-hao Zhang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Boundary Conditions ◽  
Material Model ◽  
Cantilever Beams ◽  
Element Analysis ◽  
Material Models ◽  
The Finite Element Analysis ◽  
Selection Of ◽  
Good Agreement

The objective of this research was to investigate the effects of material models, element types, and boundary conditions on the consistency of finite element analysis. Two cantilever beams were used; one made of stainless steel SUS301 3/4H and the other made of polymer polyoxymethylene. The load–deflection curves of the two cantilever beams obtained by experiments were compared to those obtained by finite element analysis, where the material models—including bilinear, trilinear, and multi-linear—were used. Four element types—beam, plane stress, shell, and solid—were also employed with the material models to obtain the simulated load–deflection curves of the cantilever beams. It was found that bilinear material models had the stiffest behavior due to their overestimated yield strength. In addition, by applying a finite displacement to simulate the grip of the cantilever beams, the discrepancy between the simulated permanent set and the experimental set could be reduced from 80% to 5%. To sum up, both the selection of the material model and the setup of the boundary conditions are critical for obtaining good agreement between the finite element analysis results and the experimental data.

scholarly journals Calibration of Failure Criteria for Additively Manufactured Metallic Materials

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3442
Author(s):  
Grzegorz Socha
Keyword(s):  
Failure Criterion ◽  
Failure Strain ◽  
Pure Shear ◽  
Ductile Failure ◽  
Failure Criteria ◽  
Calibration Procedure ◽  
Metallic Materials ◽  
Ductile Materials ◽  
Failure Models

A new version of failure criterion for additively manufactured materials, together with simple and accurate calibration procedures, is proposed and experimentally verified in this paper. The proposition is based on void growth-based ductile failure models. The failure criterion for ductile materials proposed by Hancock–Mackenzie was calibrated using simple methods and accessories. The calibration procedure allows the determination of failure strain under pure shear. The method is accurate and simple due to the fact that it prevents strain localization disturbing stress distribution at the failure zone. The original criterion was modified to better suit the deformation behavior of additively manufactured materials. Examples of calibration of the original and modified failure criteria for additively manufactured 316L alloy steel is also given in this paper, along with analyses of the obtained results.

A Data-Driven Process for Estimating Nonlinear Material Models

2011 ◽  
Vol 50-51 ◽  
pp. 599-604 ◽  
Author(s):  
X.Y. Kou ◽  
S.T. Tan ◽  
Hod Lipson
Keyword(s):  
Numerical Algorithms ◽  
Material Model ◽  
Tensile Tests ◽  
Data Driven ◽  
Nonlinear Material ◽  
Element Analysis ◽  
Material Models ◽  
Cross Section Area ◽  
Wide Range ◽  
New Material

Driven by the wide range of new material properties offered by multi-material 3D printing, there is emerging need to create predictive material models for these materials. A data driven process for estimating nonlinear material model is presented in this paper. In contrast with classical methods which derive the engineering stress-strain relationship assuming constant cross-section area and fixed length of a specimen, the proposed approach takes full advantage of 3D geometry of the specimen to estimate the material models. Give a hypothetical material model, virtual tensile tests are performed using Finite Element Analysis (FEA) method, and the parameters of the material model are estimated by minimizing the discrepancies of the virtual responses and the experimental results. The detailed material models, numerical algorithms as well as the optimization approaches are presented and finally preliminary results are offered.

Concrete Material Models in LS-DYNA for Impact Analysis of Reinforced Concrete Structures

2014 ◽  
Vol 566 ◽  
pp. 173-178
Author(s):  
M.A.K.M. Madurapperuma ◽  
Kazukuni Niwa
Keyword(s):  
Reinforced Concrete ◽  
High Speed ◽  
Impact Analysis ◽  
Material Model ◽  
Material Behavior ◽  
Single Element ◽  
Element Analysis ◽  
Material Models ◽  
Concrete Material ◽  
Rc Structures

Performance of three widely used concrete material models available in LS-DYNA is compared using experimental results of drop-weight impact on a reinforced concrete (RC) beam and high speed aircraft engine missile impact on an RC wall. An overview of these material models and typical concrete material behavior shown by these models using single element analysis are also presented. The study is useful for users who have limited experience on the selection of an appropriate material model for concrete in impact simulation of RC structures.

scholarly journals A Plane Stress Failure Criterion for Inorganically-Bound Core Materials

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 247
Author(s):  
Philipp Lechner ◽  
Christoph Hartmann ◽  
Florian Ettemeyer ◽  
Wolfram Volk
Keyword(s):  
Finite Element ◽  
Plane Stress ◽  
Failure Criterion ◽  
Axial Stress ◽  
Material Model ◽  
Failure Criteria ◽  
Plane Stress State ◽  
Testing Methods ◽  
Coulomb Model ◽  
Core Materials

Inorganically-bound core materials are used in foundries in high quantities. However, there is no validated mechanical failure criterion, which allows performing finite-element calculations on the core geometries, yet. With finite-element simulations, the cores could be optimised for various production processes from robotic core handling to the decoring process after the casting. To identify a failure criterion, we propose testing methods, that enable us to investigate the fracture behaviour of inorganically-bound core materials. These novel testing methods induce multiple bi-axial stress states into the specimens and are developed for cohesive frictional materials in general and for sand cores in particular. This allows validating failure criteria in principal stress space. We found that a Mohr-Coulomb model describes the fracture of inorganic core materials in a plane stress state quite accurately and adapted it to a failure criterion, which combines the Mohr-Coulomb model with the Weakest-Link theory in one consistent mechanical material model. This novel material model has been successfully utilised to predict the fracture force of a Brazilian test. This prediction is based on the stress fields of a finite element method (FEM) calculation.

Sign in / Sign up

Export Citation Format

Share Document