The uniaxial and biaxial, monotonic and cyclic plasticity behaviour of a lead alloy model material

1983 ◽  
Vol 18 (2) ◽  
pp. 125-133 ◽  
Author(s):  
T H Hyde
Keyword(s):  
Cyclic Loading ◽  
Cyclic Hardening ◽  
Model Material ◽  
Monotonic Loading ◽  
Biaxial Stress ◽  
Cyclic Plasticity ◽  
Lead Alloy ◽  
Material Behaviour ◽  
Loading Tests ◽  
Chill Cast

A chill-cast, antimony-arsenic-lead alloy model material has been used to investigate the monotonic and cyclic loading, uniaxial and biaxial plasticity behaviour of a metal at elevated temperature, i.e., T/ Tm ≈ 0.5. For the lead alloy used, a post-machining heat treatment of 96h at 100 C considerably reduced the scatter in the material behaviour. Uniaxial monotonic loading tests showed that the behaviour is relatively independent of temperature and strain-rate for strains less than about 1 per cent. Under cyclic loading conditions, between fixed strain limits, a stable hysteresis loop is obtained after the first cycle for both uniaxial and biaxial stress systems. By taking into account the biaxiality ratio and the increase in yield-range caused by cyclic hardening, the uniaxial and biaxial, cyclic plasticity behaviour was reasonably accurately predicted from the uniaxial, monotonic loading behaviour.

Quantitative Evaluation of Dislocation Structure Induced by Cyclic Plasticity

2007 ◽  
Vol 345-346 ◽  
pp. 49-52 ◽  
Author(s):  
Tsuyoshi Mayama ◽  
Katsuhiko Sasaki ◽  
Yoshihiro Narita
Keyword(s):  
Cyclic Loading ◽  
Quantitative Evaluation ◽  
Strain Amplitude ◽  
Dislocation Structure ◽  
Evaluation Method ◽  
Cyclic Hardening ◽  
Cyclic Softening ◽  
Cyclic Plasticity ◽  
Loading Test ◽  
Loading Tests

In the present study, a new approach is conducted to evaluate dislocation structure induced by cyclic plasticity. First, cyclic plastic loading tests are carried out up to 100 cycles with three different small strain amplitudes on SUS316L stainless steel at room temperature. The test result presents the dependence of the strain amplitude on cyclic hardening and softening behaviors. Specifically, it is found that the cyclic loading test with strain amplitude of 0.25% shows both cyclic hardening and cyclic softening, while the cyclic loading tests with strain amplitudes of 0.75% and 1.0% show no cyclic softening. Secondly, the dislocation structures of the specimens after cyclic loading are observed by using a transmission electron microscope (TEM), and this observation reveals that the dislocation structure after cyclic loading test depends on the strain amplitude. Finally, a quantitative evaluation method of the dislocation structure is also proposed. The TEM images are converted into binary images and the resolution dependence of the generated binary image is used to visualize the characteristics of the dislocation structure. The relationship between strain amplitudes of cyclic plasticity and dislocation structure organization is clarified by the evaluation method. Finally, the heterogeneity of the dislocation structure is discussed.

A Phenomenological Model for Cyclic Plasticity

1997 ◽  
Vol 119 (1) ◽  
pp. 7-11 ◽  
Author(s):  
Dar-Yun Chiang
Keyword(s):  
Cyclic Loading ◽  
Phenomenological Model ◽  
Material Properties ◽  
Experimental Studies ◽  
Cyclic Hardening ◽  
Analytical Models ◽  
Cyclic Plasticity ◽  
Loading Conditions ◽  
Microstructural Behavior ◽  
Distributed Elements

A phenomenological model is proposed for cyclic plasticity based on the concept of distributed elements, which is capable of reflecting microstructural behavior of real materials under multiaxial cyclic loading conditions. By investigating the detailed behavior of the model, various important phenomena and effects of materials in cyclic plasticity can be elucidated. Generalization of the model is also done to include cyclic hardening effects. A thorough understanding of these complicated response mechanisms and material properties provides useful insight and guidelines for validating analytical models and for performing experimental studies in the related areas of cyclic plasticity.

scholarly journals Viscoplastic Parametric Analysis of Cylindrical Specimen Under Cyclic Behaviour

2021 ◽  
pp. 75-82
Author(s):  
Panagiotis J. Charitidis
Keyword(s):  
Cyclic Loading ◽  
Numerical Study ◽  
Kinematic Hardening ◽  
Cyclic Hardening ◽  
Material Model ◽  
Cyclic Plasticity ◽  
Axial Deformation ◽  
Cyclic Behaviour ◽  
Von Mises ◽  
Cyclic Plasticity Model

The present study tries to present a cyclic hardening model with the aim to simulate quantitatively the material response under strain controlled cyclic loading in tension-compression, of specified axial deformation. A numerical study was carried out to investigate the cyclic constitutive behaviour of alloy Indium under viscoplastic deformation. The analysis was performed under prescribed symmetric strain-controlled cyclic loading. The model contains both isotropic and kinematic hardening components, while the analysis were performed using Comsol Multiphysics for only 60 seconds duration. The kinematic hardening was described by using multiple back stresses. Multiple back stresses can provide a smoother transition between the elastic and plastic deformation, and it improves the general shape of the hysteresis loop. Two cases (geometries) have been examined in this study. From the material model and finite element cyclic plasticity model results, it is found that for the same parameters, but different dimensions there is difference on the stress-strain curves as well as on the von Mises stresses.

scholarly journals Cyclic Soft/Hardening and Microscopic Mechanism of GS-20Mn5

2021 ◽  
Author(s):  
Zongyuan Zou ◽  
Doudou Liu ◽  
Shuting Han ◽  
Chunyan Song ◽  
Hongzhong Wang
Keyword(s):  
Cyclic Loading ◽  
Mechanical Response ◽  
Cast Steel ◽  
Cyclic Hardening ◽  
Cyclic Softening ◽  
Offshore Platforms ◽  
Microscopic Mechanism ◽  
Tem Analysis ◽  
Loading Tests ◽  
Cyclic Loading Tests

Abstract The cyclic plastic characteristics of metal materials are different from the deformation characteristics under monotonic loading, which has an important effect on the safety of structures in service under cyclic loading. However, GS-20Mn5, which is commonly used in large hydraulic machine beams, offshore platforms and large Bridges, is still lacking the studies of mechanical response characteristics under cyclic loading. In this study, the cyclic softening/hardening characteristics of GS-20Mn5 are studied by a series of cyclic loading tests under uniaxial strain control. Combined with transmission electron microscope (TEM) analysis of cyclic loading tests under typical strain levels, the microscopic mechanism of cyclic softening/hardening is discussed. The results show that the cyclic softening/hardening properties of GS-20Mn5 cast steel are sensitive to amplitudes and cycles. At smaller strain amplitudes (0.16%,0.2% and 0.3%), the cyclic hardening properties of GS-20Mn5 cast steel are rapid at the beginning of the cycle, followed by cyclic softening and then slow secondary cyclic hardening at the end. However, under larger strain amplitudes (0.4% and 0.5%), the cyclic hardening continues during the cyclic loading, and the hardening rate is bigger at the beginning of the cyclic loading and smaller at the later cyclic stage. The cyclic softening/hardening characteristics of GS-20Mn5 cast steel are related to the dislocation structure of ferrite and pearlite. Taking the strain amplitude of 0.2% as an example, the initial cyclic hardening is mainly caused by the proliferation and interaction of dislocations in ferrite. Dislocation spots and cell walls in ferrite grains are mainly caused cyclic softening at the initial stage, the secondary cyclic hardening is directly related to dislocation proliferation and entanglement in pearlite.

Comparative study of the effective parameters on residual stress relaxation in welded aluminum plates under cyclic loading

2020 ◽  
Vol 21 (5) ◽  
pp. 505
Author(s):  
Yousef Ghaderi Dehkordi ◽  
Ali Pourkamali Anaraki ◽  
Amir Reza Shahani
Keyword(s):  
Residual Stress ◽  
Cyclic Loading ◽  
Stress Relaxation ◽  
Stress Amplitude ◽  
Cyclic Plasticity ◽  
Mean Stress ◽  
Effective Parameters ◽  
Perfect Plasticity ◽  
Residual Stress Relaxation ◽  
Aluminum Plates

The prediction of residual stress relaxation is essential to assess the safety of welded components. This paper aims to study the influence of various effective parameters on residual stress relaxation under cyclic loading. In this regard, a 3D finite element modeling is performed to determine the residual stress in welded aluminum plates. The accuracy of this analysis is verified through experiment. To study the plasticity effect on stress relaxation, two plasticity models are implemented: perfect plasticity and combined isotropic-kinematic hardening. Hence, cyclic plasticity characterization of the material is specified by low cycle fatigue tests. It is found that the perfect plasticity leads to greater stress relaxation. In order to propose an accurate model to compute the residual stress relaxation, the Taguchi L18 array with four 3-level factors and one 6-level is employed. Using statistical analysis, the order of factors based on their effect on stress relaxation is determined as mean stress, stress amplitude, initial residual stress, and number of cycles. In addition, the stress relaxation increases with an increase in mean stress and stress amplitude.

scholarly journals Study of biaxial mechanical properties of the passive pig heart: material characterisation and categorisation of regional differences

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Fulufhelo Nemavhola
Keyword(s):  
Mechanical Properties ◽  
Constitutive Model ◽  
Computational Models ◽  
Heart Diseases ◽  
Interventricular Septum ◽  
Model Material ◽  
Biaxial Test ◽  
Material Behaviour ◽  
Material Parameters ◽  
Biaxial Tests

AbstractRegional mechanics of the heart is vital in the development of accurate computational models for the pursuit of relevant therapies. Challenges related to heart dysfunctioning are the most important sources of mortality in the world. For example, myocardial infarction (MI) is the foremost killer in sub-Saharan African countries. Mechanical characterisation plays an important role in achieving accurate material behaviour. Material behaviour and constitutive modelling are essential for accurate development of computational models. The biaxial test data was utilised to generated Fung constitutive model material parameters of specific region of the pig myocardium. Also, Choi-Vito constitutive model material parameters were also determined in various myocardia regions. In most cases previously, the mechanical properties of the heart myocardium were assumed to be homogeneous. Most of the computational models developed have assumed that the all three heart regions exhibit similar mechanical properties. Hence, the main objective of this paper is to determine the mechanical material properties of healthy porcine myocardium in three regions, namely left ventricle (LV), mid-wall/interventricular septum (MDW) and right ventricle (RV). The biomechanical properties of the pig heart RV, LV and MDW were characterised using biaxial testing. The biaxial tests show the pig heart myocardium behaves non-linearly, heterogeneously and anisotropically. In this study, it was shown that RV, LV and MDW may exhibit slightly different mechanical properties. Material parameters of two selected constitutive models here may be helpful in regional tissue mechanics, especially for the understanding of various heart diseases and development of new therapies.

Cyclic Plasticity for Nonproportional Paths: Part 1—Cyclic Hardening, Erasure of Memory, and Subsequent Strain Hardening Experiments

1978 ◽  
Vol 100 (1) ◽  
pp. 96-103 ◽  
Author(s):  
H. S. Lamba ◽  
O. M. Sidebottom
Keyword(s):  
Strain Hardening ◽  
Effective Strain ◽  
Strain Range ◽  
Cyclic Hardening ◽  
Cyclic Plasticity ◽  
Phase Cycling ◽  
Strain Behavior ◽  
Subsequent Yield Surface ◽  
Strain Hardening Behavior ◽  
Annealed Copper

Extensive experiments were conducted on annealed copper under cyclic nonproportional strain histories. After cyclically stabilizing the material by uniaxial cycling, out-of-phase axial-shear strain cycling for the same effective strain range caused additional increases in stress amplitudes to restabilized levels. Following cyclic stabilization of the material under out-of-phase cycling, a cycle whose effective strain amplitude was comparable to those of previous cycles resulted in stress-strain behavior unique to that cycle and independent of prior stable deformation. The experimental verification of this material property, which has been the subject of much conjecture, allowed the design of a fundamental class of experiments that determined the subsequent yield surface and strain hardening behavior from only one specimen.

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