scholarly journals Finite Element Implementation of a Temperature-Dependent Cyclic Plastic Model for SA508-3 Steel

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 955 ◽  
Author(s):  
Jun Tian ◽  
Jian Li ◽  
Hai Xie ◽  
Yu Yang ◽  
Qianhua Kan
Keyword(s):  
Finite Element ◽  
Kinematic Hardening ◽  
Cyclic Softening ◽  
Image Correlation ◽  
Temperature Dependent ◽  
Strain Fields ◽  
Plastic Model ◽  
Cyclic Plastic ◽  
Hardening Rule ◽  
Nonuniform Strain

A new temperature-dependent cyclic plastic model, combining the nonlinear cyclic softening and kinematic hardening rules is established for a nuclear material of SA508-3 steel. A modified isotropic hardening rule is proposed to capture the temperature-dependent cyclic softening, and a modified kinematic hardening rule is established to improve the prediction of the ratcheting behavior by introducing an exponential function related to the accumulated plastic strain. The stress is updated by the radial return mapping algorithm based on the backward Euler integration. A new expression of consistent tangent modulus for the equilibrium iteration is derived, and then the proposed model is implemented into the finite element software ABAQUS by using the user material subroutine (UMAT) to simulate the temperature-dependent ratcheting behaviors of SA508-3 steel. Finally, the ratcheting evolutions of notched bars at elevated temperature are obtained by uniaxial stress-controlled cyclic tests, and the nonuniform strain fields on the surface of plates with a center hole is measured by using the digital image correlation (DIC) technology. Comparisons between experimental and simulated results of a material point and structural examples show that the implemented model can provide reasonable predictions for ratcheting behaviors and nonuniform strain fields of structures at different temperatures for SA508-3 steel.

Elastic-Plastic Finite Element Simulation and Fatigue Life Prediction for Beam and Elbow Under Cyclic Loading

2007 ◽  
Author(s):  
Xian-Kui Zhu ◽  
Brian N. Leis
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Cyclic Loading ◽  
Plastic Strain ◽  
Kinematic Hardening ◽  
Kinematic Model ◽  
Cyclic Plastic ◽  
Hardening Models ◽  
Critical Location ◽  
Cyclic Plastic Strain

Work hardening and Bauschinger effects on plastic deformation and fatigue life for a beam and an elbow under cyclic loading are examined using finite element analysis (FEA). Three typical material plastic hardening models, i.e. isotropic, kinematic and combined isotropic/kinematic hardening models are adopted in the FEA calculations. Based on the FEA results of cyclic stress and strain at a critical location and using an energy-based fatigue damage parameter, the fatigue lives are predicted for the beam and elbow. The results show that (1) the three material hardening models determine similar stress at the critical location with small differences during the cyclic loading, (2) the isotropic model underestimates the cyclic plastic strain and overestimates the fatigue life, (3) the kinematic model overestimates the cyclic plastic strain and underestimates the fatigue life, and (4) the combined model predicts the intermediate cyclic plastic strain and reasonable fatigue life.

scholarly journals A Crystallographic Homogenization Elastic/Crystal Viscoplastic Finite Element Analysis of Pure Iron Polycrystal Material by Employing the Kinematic Hardening Rule

2006 ◽  
Vol 72 (713) ◽  
pp. 1-7
Author(s):  
Eiji NAKAMACHI ◽  
Kohei FUJITA ◽  
Takehiro HAGISATO ◽  
Yasutomo UETSUJI ◽  
Hiroyuki KURAMAE ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pure Iron ◽  
Kinematic Hardening ◽  
Element Analysis ◽  
Hardening Rule

The Influence of Facet Size and Filtering on the Results of Strain Fields’ Investigation Performed on Small Surfaces Using Digital Image Correlation

2015 ◽  
Vol 732 ◽  
pp. 179-182
Author(s):  
Martin Hagara ◽  
Róbert Huňady ◽  
Matúš Kalina
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Digital Image Correlation ◽  
Numerical Solution ◽  
Digital Image ◽  
Strain Analysis ◽  
Image Correlation ◽  
Strain Fields ◽  
Tension Loading ◽  
Facet Size

The contribution deals with the investigation of the influence of facet size and smoothing on the results obtained by low-speed digital image correlation (DIC) system by strain analysis performed on specimen with a small hole loaded by tension loading. In conclusion the obtained results are verified by a numerical solution using finite element method.

scholarly journals On finite element implementation of cyclic elastoplasticity: theory, coding, and exemplary problems

2021 ◽  
Author(s):  
Cyprian Suchocki
Keyword(s):  
Finite Element ◽  
Kinematic Hardening ◽  
Constitutive Models ◽  
Small Strain ◽  
Cyclic Plasticity ◽  
Isotropic Hardening ◽  
Mapping Algorithm ◽  
Hardening Rule ◽  
Return Mapping ◽  
Cyclic Plasticity Model

AbstractIn this work the finite element (FE) implementation of the small strain cyclic plasticity is discussed. The family of elastoplastic constitutive models is considered which uses the mixed, kinematic-isotropic hardening rule. It is assumed that the kinematic hardening is governed by the Armstrong–Frederick law. The radial return mapping algorithm is utilized to discretize the general form of the constitutive equation. A relation for the consistent elastoplastic tangent operator is derived. To the best of the author’s knowledge, this formula has not been presented in the literature yet. The obtained set of equations can be used to implement the cyclic plasticity models into numerous commercial or non-commercial FE packages. A user subroutine UMAT (User’s MATerial) has been developed in order to implement the cyclic plasticity model by Yoshida into the open-source FE program CalculiX. The coding is included in the Appendix. It can be easily modified to implement any isotropic hardening rule for which the yield stress is a function of the effective plastic strain. The number of the utilized backstress variables can be easily increased as well. Several validation tests which have been performed in order to verify the code’s performance are discussed.

Long and Short Radius Elbow Experiments and Evaluation of Advanced Constitutive Models to Simulate the Responses

2015 ◽  
Author(s):  
Nazrul Islam ◽  
Matthew Fenton ◽  
Tasnim Hassan
Keyword(s):  
Finite Element ◽  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Constitutive Models ◽  
Image Correlation ◽  
Cycle Fatigue ◽  
Element Simulation ◽  
Piping Systems ◽  
Diameter Change ◽  
Dic Technique

Low-cycle fatigue (LCF) and strain ratcheting responses of long and short radius elbows are studied experimentally and analytically. Elbow piping components are widely used in piping systems, however, the prediction of their low-cycle fatigue and ratcheting responses remain a challenge. Hence, a systematic set of short and long radius elbow LCF responses are developed by prescribing displacement-controlled loading cycles with or without internal pressure. A setup comprised of four LVDTs was utilized to measure diameter change during cyclic loading. In order to evaluate the accuracy of the strain gage data, strains are also acquired using the digital image correlation (DIC) technique. Recorded fatigue responses are analyzed in understanding the differences in LCF lives between the long and short radius elbows. The Chaboche nonlinear kinematic hardening constitutive model in ANSYS and a modified version of this model are evaluated for their simulation capability against the recorded elbow responses. The experimental and finite element simulation responses are presented in this article.

scholarly journals Modelling Local Bending Stiffness of Norway Spruce Sawn Timber Using Scanned Fibre Orientation

Proceedings ◽  
2018 ◽  
Vol 2 (8) ◽  
pp. 505
Author(s):  
Min Hu ◽  
Anders Olsson ◽  
Marie Johansson ◽  
Jan Oscarsson
Keyword(s):  
Finite Element ◽  
Laser Scanning ◽  
Fibre Orientation ◽  
Three Dimensional ◽  
Element Model ◽  
High Accuracy ◽  
Bending Stiffness ◽  
Image Correlation ◽  
Strain Fields ◽  
Three Dimensional Finite Element

Strength of structural timber depends to a high degree on the occurrence of knots and on the local fibre deviation around such defects. Knowledge of local fibre orientation, obtained by laser scanning, have been utilized in a previously developed machine strength grading method. However, that method was based on rather crude assumptions regarding the fibre orientation in the interior of boards and a mechanical model that does not capture the full compliance of knotty sections. The purpose of the present study was to suggest and verify a model by which local bending stiffness can be predicted with high accuracy. This study included development of a model of fibre orientation in the interior of boards, and application of a three-dimensional finite element model that is able to capture the compliance of the board. Verification included bending of boards in laboratory and application of digital image correlation to obtain strain fields comparable to those obtained by finite element simulation. Results presented comprise strain fields of boards subjected to bending and calculated bending stiffness variation along boards. Comparisons of results indicated that models suggested herein were sufficient to capture the variation of local bending stiffness along boards with very high accuracy.

Using Digital Image Correlation Techniques and Finite Element Models for Strain-Field Analysis of a Welded Aluminium Structure

2011 ◽  
Vol 70 ◽  
pp. 123-128 ◽  
Author(s):  
Mathias Flansbjer ◽  
Torsten Sjögren
Keyword(s):  
Finite Element ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Strain Field ◽  
Base Material ◽  
Fe Analysis ◽  
Image Correlation ◽  
Micro Hardness ◽  
Strain Fields ◽  
Welding Operation

The use of aluminium in lightweight structures and corrosive environments is continuously increasing. Welding is often used to assemble different aluminium components and it is of great importance to take into account the deteriorating effect the welding operation on the aluminium’s strength when designing these structures. In the present study, the strain-fields of welded aluminium tensile specimens have been analysed by digital image correlation (DIC) techniques, micro hardness measurements and finite element (FE) modelling. The stress-strain curve of the weld material, the heat affected zone (HAZ) and the base material have been determined by tensile tests. The material properties and the extension of the HAZ were also correlated to the micro hardness. The experimental data has been used as an input to the material models of the FE analysis. The study shows that using FE-analysis in combination with strain-field determination by DIC is very powerful. The resulting strain-fields are easily compared and the FE-analysis is verified in a straightforward way. Furthermore, the results of the study suggest that micro hardness measurements could be used to derive the strength of the material affected by the welding operation.

Finite Element Analysis of V-Bending of Polypropylene Using Hydrostatic-Pressure Dependent Plastic Constitutive Equation

2007 ◽  
Vol 340-341 ◽  
pp. 1103-1108 ◽  
Author(s):  
Kunio Hayakawa ◽  
Yukio Sanomura ◽  
Mamoru Mizuno ◽  
Yukio Kasuga ◽  
Tamotsu Nakamura
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Hydrostatic Pressure ◽  
Constitutive Equations ◽  
Kinematic Hardening ◽  
Uniaxial Stress ◽  
Isotropic Hardening ◽  
Element Analysis ◽  
Hardening Rule ◽  
Stress Strain Relation

Finite element analysis of V-bending process of polypropylene was performed using hydrostatic-dependent elastic-plastic constitutive equations proposed by the present authors. Kinematic and isotropic hardening rule was employed for the plastic constitutive equations. The kinematic hardening rule was more suitable for the expression of the stress reversal in uniaxial stress - strain relation than the isotropic hardening. For the result of the finite element analysis of V-bending, the kinematic hardening rule was able to predict the experimental behavior of springback more properly than the isotropic hardening. Moreover, the effects of hydrostatic pressure-dependence were revealed by examining the calculated distribution of bending plastic strain, bending stress and the width of the bent specimen.

Delamination in the scoring and folding of paperboard

TAPPI Journal ◽  
2012 ◽  
Vol 11 (1) ◽  
pp. 61-66 ◽  
Author(s):  
DOEUNG D. CHOI ◽  
SERGIY A. LAVRYKOV ◽  
BANDARU V. RAMARAO
Keyword(s):  
Finite Element ◽  
Plane Deformation ◽  
Strain Analysis ◽  
Local Strain ◽  
Uniaxial Stress ◽  
Material Model ◽  
Element Model ◽  
Plastic Behavior ◽  
Stress Strain ◽  
Strain Fields

Delamination between layers occurs during the creasing and subsequent folding of paperboard. Delamination is necessary to provide some stiffness properties, but excessive or uncontrolled delamination can weaken the fold, and therefore needs to be controlled. An understanding of the mechanics of delamination is predicated upon the availability of reliable and properly calibrated simulation tools to predict experimental observations. This paper describes a finite element simulation of paper mechanics applied to the scoring and folding of multi-ply carton board. Our goal was to provide an understanding of the mechanics of these operations and the proper models of elastic and plastic behavior of the material that enable us to simulate the deformation and delamination behavior. Our material model accounted for plasticity and sheet anisotropy in the in-plane and z-direction (ZD) dimensions. We used different ZD stress-strain curves during loading and unloading. Material parameters for in-plane deformation were obtained by fitting uniaxial stress-strain data to Ramberg-Osgood plasticity models and the ZD deformation was modeled using a modified power law. Two-dimensional strain fields resulting from loading board typical of a scoring operation were calculated. The strain field was symmetric in the initial stages, but increasing deformation led to asymmetry and heterogeneity. These regions were precursors to delamination and failure. Delamination of the layers occurred in regions of significant shear strain and resulted primarily from the development of large plastic strains. The model predictions were confirmed by experimental observation of the local strain fields using visual microscopy and linear image strain analysis. The finite element model predicted sheet delamination matching the patterns and effects that were observed in experiments.

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