scholarly journals Yield criterion and finite strain behavior of random porous isotropic materials

2021 ◽  
Vol 85 ◽  
pp. 104143
Author(s):  
J. Hure
Keyword(s):  
Finite Strain ◽  
Yield Criterion ◽  
Isotropic Materials ◽  
Strain Behavior

IMAGE ANALYSIS BASED FINITE STRAIN MEASUREMENT OF LOCAL DEFORMATION UNDER UNIAXIAL LOAD USING NATURAL STRAIN

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Yasuyuki Kato
Keyword(s):  
Image Analysis ◽  
Strain Measurement ◽  
Finite Strain ◽  
Local Deformation ◽  
Strain Theory ◽  
Strain Behavior ◽  
Natural Strain ◽  
Strain Components ◽  
Shearing Strain ◽  
Local Deformations

This paper describes the effectiveness of image analysis based on the Natural Strain theory for measuring the finite strain. Since the additive law of strain on an identical line element can be satisfied and the rigid body rotation can clearly be removed from the shearing strain components, the Natural Strain theory is significantly effective for representing the stress-strain behavior under large elasto-plastic deformation. In this study, the strain measurements under large deformation are conducted by making use of such merits into the image analysis. In our previous studies, in order to verify the effectiveness of this method, the results of strain measurement by image analysis have been compared with the results of conventional strain measurement based on the displacement meter. Consequently, since the results of both measurements almost coincide, the validity of this image analysis has been confirmed. However, these experiments were limited to uniform deformation fields, although in the range of finite deformation. Hence, as for the local deformation, the detailed measurements have not been carried out yet in our previous study. So, in this paper, the local deformations generated under uniaxial tension and simple shear are investigated as the fundamental research. Especially, the progress of local deformations is revealed by comparing the measured values of upper and middle positions in the specimen.

scholarly journals Elastic-plastic analysis of metallic shells at finite strains

2007 ◽  
Vol 60 (2) ◽  
pp. 381-389 ◽  
Author(s):  
Eduardo Moraes Barreto Campello ◽  
Paulo de Mattos Pimenta ◽  
Peter Wriggers
Keyword(s):  
Finite Strain ◽  
Yield Criterion ◽  
Isotropic Hardening ◽  
Triangular Finite Element ◽  
Numerical Examples ◽  
Plastic Analysis ◽  
Isotropic Elasticity ◽  
Von Mises ◽  
Variable Thickness Shell ◽  
Thickness Shell

The geometrically-exact finite-strain variable-thickness shell model of [1] is reviewed in this paper and extended to the case of metallic elastoplastic shells. Isotropic elasticity and von Mises yield criterion with isotropic hardening are considered. The model is implemented within a triangular finite element and is briefly assessed by means of two numerical examples.

scholarly journals Lower Bound Yield Locus Calculations

1990 ◽  
Vol 12 (1-3) ◽  
pp. 89-101 ◽  
Author(s):  
William Hosford ◽  
Aitor Galdos
Keyword(s):  
Lower Bound ◽  
Upper Bound ◽  
Work Hardening ◽  
Stress Ratio ◽  
Yield Criterion ◽  
Yield Locus ◽  
Stress Strain ◽  
Strain Behavior ◽  
Yield Loci ◽  
The Hill

A lower-bound model for the deformation of work-hardening polycrystals is proposed. All grains are assumed to be loaded under the same stress and the stress–strain behavior is found by averaging the strains in all grains. The shapes of the yield loci have been calculated for textured metals which deform by {111} 〈110〉 slip (fcc) and by 〈111〉-pencil glide (bcc). As with the corresponding upper-bound models, the yield loci are best described by an anisotropic yield criterion with an exponent of 6 to 10 (instead of 2 as in the Hill theory). Also it is shown that a model of polycrystal deformation in which the grains are loaded to the same stress ratio (but not the same level of stresses) violates normality and is not a lower bound.

Transverse-Isotropic Elastic and Viscoelastic Solids

2004 ◽  
Vol 126 (1) ◽  
pp. 38-44 ◽  
Author(s):  
Alan D. Freed
Keyword(s):  
Finite Strain ◽  
Constitutive Theory ◽  
Simple Shearing ◽  
Viscoelastic Solids ◽  
Strain Fields ◽  
Isotropic Materials ◽  
Transverse Isotropic ◽  
Produce Strain

A set of invariants are presented for transverse-isotropic materials whose gradients produce strain fields, instead of deformation fields as is typically the case. Finite-strain theories for elastic and K-BKZ-type viscoelastic solids are derived. Shear-free and simple shearing deformations are employed to illustrate the constitutive theory.

scholarly journals The mechanical behavior of polylactic acid (PLA) films: fabrication, experiments and modelling

2019 ◽  
Author(s):  
S. M. Mirkhalaf ◽  
M. Fagerström
Keyword(s):  
Thin Films ◽  
Constitutive Model ◽  
Mechanical Behavior ◽  
Polylactic Acid ◽  
Finite Strain ◽  
Uniaxial Stress ◽  
Strain Rates ◽  
Rate Dependency ◽  
Strain Behavior ◽  
Physically Based

Abstract Polylactic acid (PLA) is one of the highly applicable bio-polymers in a wide variety of applications including medical fields and packaging. In order to quantitatively model the mechanical behavior of PLA and PLA based bio-composite materials, and also tailor new bio-composites, it is required to characterize the mechanical behavior of PLA. In this study, thin films of PLA are fabricated via hot-pressing, and tensile experiments are performed under different strain rates. To model the mechanical behavior, an elasto-viscoplastic constitutive model, developed in a finite strain setting, is adopted and calibrated. Using the physically-based constitutive model, all regimes of deformation under uniaxial stress state, including post-yield softening, were adequately captured in the simulations. Also, the rate dependency of the stress–strain behavior was properly modelled.

scholarly journals AVALIAÇÃO DO DESEMPENHO DO MÉTODO CPPM EM ANÁLISES ELASTOPLÁSTICAS

2016 ◽  
Vol 12 (1) ◽  
Author(s):  
Maria Paz Duque Gutiérrez ◽  
William Taylor Matias Silva
Keyword(s):  
Projection Method ◽  
Yield Criterion ◽  
Flow Rule ◽  
Analytical Formulation ◽  
Strain Behavior ◽  
Nonlinear Responses ◽  
Von Mises ◽  
Closest Point Projection ◽  
Point Projection ◽  
Nonlinear Hardening

RESUMO: O método de projeção do ponto mais próximo (CPPM, closest point projection method) é amplamente utilizado quando se apresentam respostas não lineares no comportamento dos materiais. Este artigo destina-se ao detalhamento e formulação analítica do método e avaliar com exemplos simples seu desempenho utilizando distintas leis de endurecimento não lineares para definir a evolução das deformações plásticas. O método é implementado sob uma cinemática de deformações infinitesimais. É considerado que o material possui propriedades elásticas constantes. O critério de escoamento de von Mises é utilizado com uma regra associativa de fluxo para descrever o comportamento tensão-deformação do material. A principal contribuição deste trabalho é verificar a robustez do método e apresentar explicação completa da formulação analítica. ABSTRACT: The closest point projection method is widely used when nonlinear responses occur in the behavior of the materials. The aim of this work is detailing its analytical formulation with simple examples and evaluates the performance of the method using different nonlinear hardening laws to define the evolution of plastic deformation. The method is implemented under a kinematic of infinitesimal strains, it is considered a material with constant elastic properties, the von Mises yield criterion and an associative flow rule is used to describe the stress - strain behavior of the material. The main contribution of this work is to verify the robustness of the method and the complete explanation of the analytical formulation. RESUMEN. El método de proyección al punto más próximo (CPPM, closest point projection method) es ampliamente utilizado cuando se presentan respuestas no lineales en el comportamiento de los materiales. Se pretende con este trabajo detallar su formulación analítica y evaluar con ejemplos simples el desempeño del método utilizando diferentes leyes de endurecimiento no lineales para definir la evolución de las deformaciones plásticas. El método es implementado bajo una cinemática de deformaciones infinitesimales. Se considera un material con propiedades elásticas constantes, se emplea el criterio de fluencia de von Mises y una regla asociativa de flujo para describir el comportamiento tensión - deformación del material. La principal contribución de este trabajo es la verificación de la robustez del método y la explicación completa de la formulación analítica.

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