A method for the simultaneous derivation of tensile and compressive behaviour of materials under Bauschinger effect using bend tests

2006 ◽  
Vol 220 (10) ◽  
pp. 1509-1518 ◽  
Author(s):  
G Urriolagoitia-Sosa ◽  
J F Durodola ◽  
A Lopez-Castro ◽  
N A Fellows
Keyword(s):  
Compressive Stress ◽  
Bauschinger Effect ◽  
Experimental Testing ◽  
Kinematic Hardening ◽  
Theoretical Data ◽  
Test Results ◽  
Stress Strain ◽  
Element Analysis ◽  
Strain Behaviour ◽  
Hardening Rules

Some materials exhibit Bauschinger effect as a consequence of strain hardening. The effect leads to asymmetric tensile and compressive stress-strain behaviour. If the hardening behaviour in either tension or compression is known, combined isotropic/kinematic hardening rules can be used to estimate the hardening behaviour in the other. These rules are, however, only approximate empirical relationships that are derived from the analysis of separate tensile and compressive test results. This article presents a method for the simultaneous derivation of tensile and compressive stress-strain behaviour from bending tests only. The information required is strains at the top and bottom surfaces of beams and moment as load is incrementally applied. The derivation of the method is based on the application of tensile and moment equilibrium conditions. The proposed method is tested on theoretical data obtained from finite-element analysis and as well as on data from actual experimental testing. The agreement between the results obtained is very good.

Determination of Tensile and Compressive Stress Strain Curves from Bend Tests

2004 ◽  
Vol 1-2 ◽  
pp. 133-138 ◽  
Author(s):  
G. Urriolagoitia-Sosa ◽  
J.F. Durodola ◽  
N.A. Fellows
Keyword(s):  
Compressive Stress ◽  
Inverse Method ◽  
Bauschinger Effect ◽  
Stress Strain ◽  
Bending Tests ◽  
Strain Behaviour ◽  
Strain Data ◽  
Tension And Compression ◽  
Bend Tests

A new inverse method has been developed for the simultaneous derivation of tensile and compressive stress strain behaviour from bending tests only. This new procedure can be applied to materials having asymmetric tensile and compressive stress strain behaviour and also materials that have been previously strain hardened (Bauschinger Effect). This paper presents results obtained using the new method and compares them with experimentally obtained tensile and compressive stress strain curves. The agreement of the derived stress strain data in tension and compression is encouraging.

Numerical Modeling and Analytical Investigation of Autofrettage Process on the Fluid End Module of Fracture Pumps

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Mahdi Kiani ◽  
Roger Walker ◽  
Saman Babaeidarabad
Keyword(s):  
Residual Stresses ◽  
Kinematic Hardening ◽  
Analytical Formula ◽  
Strain Analysis ◽  
Material Model ◽  
Analytical Investigation ◽  
Stress Strain ◽  
Element Analysis ◽  
Hardening Material ◽  
Strain Evolution

One of the most important components in the hydraulic fracturing is a type of positive-displacement-reciprocating-pumps known as a fracture pump. The fluid end module of the pump is prone to failure due to unconventional drilling impacts of the fracking. The basis of the fluid end module can be attributed to cross bores. Stress concentration locations appear at the bores intersections and as a result of cyclic pressures failures occur. Autofrettage is one of the common technologies to enhance the fatigue resistance of the fluid end module through imposing the compressive residual stresses. However, evaluating the stress–strain evolution during the autofrettage and approximating the residual stresses are vital factors. Fluid end module geometry is complex and there is no straightforward analytical solution for prediction of the residual stresses induced by autofrettage. Finite element analysis (FEA) can be applied to simulate the autofrettage and investigate the stress–strain evolution and residual stress fields. Therefore, a nonlinear kinematic hardening material model was developed and calibrated to simulate the autofrettage process on a typical commercial triplex fluid end module. Moreover, the results were compared to a linear kinematic hardening model and a 6–12% difference between two models was observed for compressive residual hoop stress at different cross bore corners. However, implementing nonlinear FEA for solving the complicated problems is computationally expensive and time-consuming. Thus, the comparison between nonlinear FEA and a proposed analytical formula based on the notch strain analysis for a cross bore was performed and the accuracy of the analytical model was evaluated.

Predictions of microtorsional experiments by micropolar plasticity

2005 ◽  
Vol 461 (2053) ◽  
pp. 189-205 ◽  
Author(s):  
Paschalis Grammenoudis ◽  
Charalampos Tsakmakis
Keyword(s):  
Size Effects ◽  
Bauschinger Effect ◽  
Kinematic Hardening ◽  
Circular Cylinders ◽  
Isotropic Hardening ◽  
Gradient Plasticity ◽  
Material Response ◽  
Micropolar Plasticity ◽  
Classical Plasticity ◽  
Hardening Rules

Kinematic hardening rules are employed in classical plasticity to capture the so–called Bauschinger effect. They are important when describing the material response during reloading. In the framework of thermodynamically consistent gradient plasticity theories, kinematic hardening effects were first incorporated into a micropolar plasticity model by Grammenoudis and Tsakmakis. The aim of the present paper is to investigate this model by predicting size effects in torsional loading of circular cylinders. It is shown that kinematic hardening rules compared with isotropic hardening rules, as adopted in the paper, provide more possibilities for modelling size effects in the material response, even if only monotonous loading conditions are considered.

scholarly journals A Simplified Method for Elastic-Plastic-Creep Structural Analysis

1985 ◽  
Vol 107 (1) ◽  
pp. 231-237 ◽  
Author(s):  
A. Kaufman
Keyword(s):  
Finite Element ◽  
Stress Relaxation ◽  
Kinematic Hardening ◽  
Nonlinear Finite Element ◽  
Strain History ◽  
Stress Strain ◽  
Element Analysis ◽  
Inelastic Analysis ◽  
Simplified Method ◽  
Time Required

A simplified inelastic analysis computer program (ANSYMP) was developed for predicting the stress-strain history at the critical location of a thermomechanically cycled structure from an elastic solution. The program uses an iterative and incremental procedure to estimate the plastic strains from the material stress-strain properties and a plasticity hardening model. Creep effects can be calculated on the basis of stress relaxation at constant strain, creep at constant stress or a combination of stress relaxation and creep accumulation. The simplified method was exercised on a number of problems involving uniaxial and multiaxial loading, isothermal and nonisothermal conditions, dwell times at various points in the cycles, different materials, and kinematic hardening. Good agreement was found between these analytical results and nonlinear finite element solutions for these problems. The simplified analysis program used less than 1 percent of the CPU time required for a nonlinear finite element analysis.

Correlation of strength, rubber content, and water to cement ratio in rubberized concrete

2005 ◽  
Vol 32 (6) ◽  
pp. 1075-1081 ◽  
Author(s):  
Ashraf M Ghaly ◽  
James D Cahill IV
Keyword(s):  
Compressive Stress ◽  
Experimental Testing ◽  
Concrete Strength ◽  
Crumb Rubber ◽  
Test Results ◽  
Rubberized Concrete ◽  
Rubber Content ◽  
Research Project ◽  
Conventional Concrete ◽  
Cement Ratio

Waste rubber tires that cannot be processed for useful applications are numbered in the millions around the world. The build up of old rubber tires in landfills is commonly considered a major threat to the environment, and it is unquestionably a burden on landfill space. This research project was an investigation into the possibility of using fine rubber particles in concrete mixtures. The experimental testing program was designed to study the effect of the addition of crumb rubber, as replacement of a portion of fine aggregates (sand), on the strength of concrete. Rubber was added to concrete in quantities of 5%, 10%, and 15% by volume of the mixture. Three different water/cement ratios were used: 0.47, 0.54, and 0.61. A total of 180 concrete cubes were made. The cubes were tested in compression at 1, 7, 14, 21, and 28 d with the load continuously and automatically measured until failure. The load values were used to calculate compressive stress as related to different rubber contents and water/cement ratios. Compression test results were used to develop several plots relating rubber content and water/cement ratio to compressive stress of concrete. Test results gathered in this research project indicated that the addition of crumb rubber to concrete results in a reduced strength as compared with that of conventional concrete. Based on the experimental results, correlations have been developed to estimate the reduction in concrete strength as a function of the rubber content in the mix.Key words: compressive strength, concrete, crumb rubber, rubberized concrete.

A General Autofrettage Model of a Thick-Walled Cylinder Based on Tensile-Compressive Stress-Strain Curve of a Material

2005 ◽  
Vol 40 (6) ◽  
pp. 599-607 ◽  
Author(s):  
X. P Huang
Keyword(s):  
Strain Hardening ◽  
Compressive Stress ◽  
Bauschinger Effect ◽  
Strain Curve ◽  
Accurate Prediction ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Perfectly Plastic ◽  
Hardening Models ◽  
Elastic Perfectly Plastic

The basic autofrettage theory assumes elastic-perfectly plastic behaviour. Because of the Bauschinger effect and strain-hardening, most materials do not display elastic-perfectly plastic properties and consequently various autofrettage models are based on different simplified material strain-hardening models, which assume linear strain-hardening or power strain-hardening or a combination of these strain-hardening models. This approach gives a more accurate prediction than the elastic-perfectly plastic model and is suitable for different strain-hardening materials. In this paper, a general autofrettage model that incorporates the material strain-hardening relationship and the Bauschinger effect, based upon the actual tensile-compressive stress-strain curve of a material is proposed. The model incorporates the von Mises yield criterion, an incompressible material, and the plane strain condition. Analytic expressions for the residual stress distribution have been derived. Experimental results show that the present model has a stronger curve-fitting ability and gives a more accurate prediction. Several other models are shown to be special cases of the general model presented in this paper. The parameters needed in the model are determined by fitting the actual tensile-compressive curve of the material, and the maximum strain of this curve should closely represent the maximum equivalent strain at the inner surface of the cylinder under maximum autofrettage pressure.

A Finite Element Analysis of the Effect of Hardening Rules on the Indentation Test

1998 ◽  
Vol 120 (2) ◽  
pp. 143-148 ◽  
Author(s):  
N. Huber ◽  
Ch. Tsakmakis
Keyword(s):  
Finite Element Method ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Half Space ◽  
Kinematic Hardening ◽  
Indentation Test ◽  
Rigid Sphere ◽  
The Finite Element Method ◽  
Element Analysis ◽  
Hardening Rules

Using the Finite Element Method, an analysis is given of the indentation of an elasticplastic half-space by a rigid sphere. In particular, attention is focused on the effect of hardening rules on the material response. The materials considered are supposed to exhibit isotropic and kinematic hardening. Moreover, it is shown that the possibility of similar behavior due to effects of friction can be ruled out.

Elastic-Plastic Finite Element Analysis of the Effect of the Compressive Loading on Fatigue Crack Tip Parameters

2008 ◽  
Vol 392-394 ◽  
pp. 980-984 ◽  
Author(s):  
Y. Sha ◽  
Hui Tang ◽  
Jia Zhen Zhang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Compressive Stress ◽  
Kinematic Hardening ◽  
Compressive Loading ◽  
Crack Tip ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Element Analysis ◽  
Elastic Plastic

In this paper, a detailed elastic-plastic finite element analysis of the effect of the compressive loading on crack tip plasticity is studied based on the material’s kinematic hardening model. Five centre-cracked panel specimens with different crack lengths are analyzed. The analysis shows that in a tension-compression loading the maximum spread of the crack tip reverse plastic zone increases with the increase of the compressive stress and the near crack tip opening displacement decreases with the increase of the compressive stress at the same nominal stress intensity factor. The applied compressive stress is the main factor controlling the near crack tip parameters.

Experimental and Numerical Study of Uniaxial and Multiaxial Stress-Strain Behaviour of R7T Wheel Steel

2015 ◽  
Vol 732 ◽  
pp. 91-94 ◽  
Author(s):  
Radim Halama ◽  
Michal Šofer ◽  
František Fojtík ◽  
Aleksandros Markopoulos
Keyword(s):  
Numerical Study ◽  
Kinematic Hardening ◽  
Wheel Steel ◽  
Isotropic Hardening ◽  
Good Prediction ◽  
Main Attention ◽  
Stress Strain ◽  
Strain Behavior ◽  
Hardening Rule ◽  
Strain Behaviour

This paper is focused on the correct description of stress-strain behavior of the R7T steel. An experimental study on the wheel steel specimens including uniaxial as well as multiaxial tests has been conducted. The main attention was paid to such effects as ratcheting and nonproportional hardening of the material. A cyclically stable behavior of the steel under higher amplitude loading was found. The MAKOC model, which is based on AbdelKarim-Ohno kinematic hardening rule and Calloch isotropic hardening rule, has been applied in subsequent finite element simulations. The numerical results show very good prediction of stress-strain behaviour of the wheel steel.

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