A Practical Two Surface Plasticity Theory

1975 ◽  
Vol 42 (3) ◽  
pp. 641-646 ◽  
Author(s):  
R. D. Krieg
Keyword(s):  
Bauschinger Effect ◽  
Kinematic Hardening ◽  
Uniaxial Stress ◽  
Plasticity Theory ◽  
Experimental Results ◽  
Limit Surface ◽  
Hardening Model ◽  
Loading Surface ◽  
Surface Plasticity ◽  
Usual Concept

A plasticity theory is presented using the usual concept of a loading surface which moves and isotropically grows, but in addition uses a “limit surface” which grows and moves independently and encloses the loading surface. The plastic stiffness is a function of the distance between the surfaces at the loading point. Characteristics of the theory are a smoother transition between elastic and plastic regions on loading, an inherent Bauschinger effect, and more latitude on the description of hardening characteristics than the traditional methods used in structural codes. The full capability of the theory requires a memory of three vectors and three scalars, while some of the foregoing characteristics can be retained with only two vectors, the same as a traditional kinematic hardening model. The multiaxial theory is presented, particularized, specialized to uniaxial stress and the equations solved. The theory is compared to uniaxial stress experimental results.

Isotropic–kinematic hardening model for coarse granular soils capturing particle breakage and cyclic loading under triaxial stress space

2016 ◽  
Vol 53 (4) ◽  
pp. 646-658 ◽  
Author(s):  
Qingsheng Chen ◽  
Buddhima Indraratna ◽  
John P. Carter ◽  
Sanjay Nimbalkar
Keyword(s):  
Cyclic Loading ◽  
Critical State ◽  
Kinematic Hardening ◽  
Plasticity Theory ◽  
Particle Breakage ◽  
Granular Soils ◽  
Stress Space ◽  
Bounding Surface ◽  
Bounding Surface Plasticity ◽  
Surface Plasticity

In this paper, a simple but comprehensive cyclic stress–strain model that incorporates particle breakage for granular soils including ballast and rockfill has been proposed on the basis of bounding surface plasticity theory within a critical state framework. Particle breakage and its effects are captured by a critical state line that is translated in voids ratio–stress space according to the dissipated energy (plastic work), through a hyperbolic function. A comprehensive equation related to particle breakage is proposed for the stress–dilatancy relationship to capture the complex dilatancy of granular soils. By extending Masing’s rule to bounding surface plasticity theory and introducing a generalized homological centre, a combined isotropic–kinematic hardening rule and a mapping rule have been established to simulate more realistically the response of gravelly soils under cyclic loading. The applicability and accuracy of this model are demonstrated by comparing its predictions with experimental results for different types of granular soils, including rockfill, under both monotonic and cyclic loading conditions. This study shows that the model can capture the characteristic features of coarse granular soils under complex loading paths.

scholarly journals Ratcheting Simulation in a Titanium-Steel Bimetallic Plate Based on the Chaboche Hardening Model

2016 ◽  
Vol 10 (4) ◽  
pp. 265-270
Author(s):  
Aleksander Karolczuk
Keyword(s):  
Residual Stresses ◽  
Kinematic Hardening ◽  
Fatigue Loading ◽  
Experimental Results ◽  
Hardening Model ◽  
The Third ◽  
Hardening Rule ◽  
Bimetallic Plate

Abstract The paper presents the results of fatigue loading simulation applied to bimetallic model using the Chaboche kinematic hardening rule. Three cases of simulations were performed: (i) without residual stresses; (ii) considering residual stresses and (iii) considering asymmetrical geometry of bimetal, i.e. cross area reducing under tension period of loading. Experimental results exhibit the ratcheting phenomenon in titanium-steel bimetallic specimens. The observed ratcheting phenomenon could be explained by the third case of simulation which is supported by detection of microcracks in the vicinity of welded area.

Effects of Hardening Models on CUO Forming and Springback Simulation of High Strength Line Pipes

2015 ◽  
Vol 817 ◽  
pp. 8-13 ◽  
Author(s):  
Qiang Ren ◽  
Tian Xia Zou ◽  
Da Yong Li
Keyword(s):  
Bauschinger Effect ◽  
Oil And Gas ◽  
Kinematic Hardening ◽  
High Strength ◽  
Isotropic Hardening ◽  
Forming Process ◽  
Hardening Model ◽  
Hardening Models ◽  
Combined Hardening ◽  
Springback Prediction

The UOE process is an effective approach for manufacturing the line pipes used in oil and gas transportation. During the UOE process, a steel plate is crimped along its edges, pressed into a circular pipe with an open-seam by the successively U-O forming stages. Subsequently, the open-seam is closed and welded. Finally, the welded pipe is expanded to obtain a perfectly round shape. In particular, during the O-forming stage the plate is suffered from distinct strain reversal which leads to the Bauschinger effect, i.e., a reduced yield stress at the start of reverse loading following forward strain. In the finite element simulation of plate forming, the material hardening model plays an important role in the springback prediction. In this study, the mechanical properties of API X90 grade steel are obtained by a tension-compression test. Three popular hardening models (isotropic hardening, kinematic hardening and combined hardening) are employed to simulate the CUO forming process. A deep analysis on the deformation and springback behaviors of the plate in each forming stage is implemented. The formed configurations from C-forming to U-forming are almost identical with three hardening models due to the similar forward hardening behaviors. Since the isotropic hardening model cannot represent the Bauschinger effect, it evaluates the higher reverse stress and springback in the O-forming stage which leads to a failure prediction of a zero open-seam pipe. On the contrary, the kinematic hardening model overestimates the Bauschinger effect so that predicts the larger open-seam value. Specifically, the simulation results using the combined hardening model show good agreement in geometric configurations with the practical measurements.

Characterization of Steels Using a Revised Kinematic Hardening Model Incorporating Bauschinger Effect

2002 ◽  
Author(s):  
Anthony P. Parker ◽  
Edward Troiano ◽  
John H. Underwood ◽  
Charles Mossey
Keyword(s):  
Bauschinger Effect ◽  
Kinematic Hardening ◽  
Hardening Model

The Role of Plasticity Theory on the Predicted Residual Stress Field of Weld Structures

2013 ◽  
Vol 772 ◽  
pp. 65-71 ◽  
Author(s):  
Ondrej Muránsky ◽  
Cory J. Hamelin ◽  
Mike C. Smith ◽  
Phillip J. Bendeich ◽  
Lyndon Edwards
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Kinematic Hardening ◽  
Plasticity Theory ◽  
Isotropic Hardening ◽  
Residual Stress Field ◽  
Hardening Model ◽  
Mixed Hardening ◽  
Weld Residual Stress

Constitutive plasticity theory is commonly applied to the numerical analysis of welds in one of three ways: using an isotropic hardening model, a kinematic hardening model, or a mixed isotropic-kinematic hardening model. The choice of model is not entirely dependent on its numerical accuracy, however, as a lack of empirical data will often necessitate the use of a specific approach. The present paper seeks to identify the accuracy of each formalism through direct comparison of the predicted and actual post-weld residual stress field developed in a three-pass 316LN stainless steel slot weldment. From these comparisons, it is clear that while the isotropic hardening model tends to noticeably over-predict and the kinematic hardening model slightly under-predict the residual post-weld stress field, the results using a mixed hardening model are quantitatively accurate. Even though the kinematic hardening model generally provides more accurate results when compared to an isotropic hardening formalism, the latter might be a more appealing choice to engineers requiring a conservative design regarding weld residual stress.

Characterization of Steels Using a Revised Kinematic Hardening Model Incorporating Bauschinger Effect

2003 ◽  
Vol 125 (3) ◽  
pp. 277-281 ◽  
Author(s):  
Anthony P. Parker ◽  
Edward Troiano ◽  
John H. Underwood ◽  
Charles Mossey
Keyword(s):  
Bauschinger Effect ◽  
Kinematic Hardening ◽  
Compressive Loading ◽  
Tensile Loading ◽  
Linear Strain ◽  
Subsequent Work ◽  
Hardening Model ◽  
New Variant ◽  
Initial Load

A new variant of the nonlinear kinematic hardening model is proposed which accommodates both nonlinear and linear strain hardening during initial tensile loading and reduced elastic modulus during initial load reversal. It also incorporates the Bauschinger effect, as a function of prior tensile plastic strain, during the nonlinear compressive loading phase. The model is shown to fit experimental data from a total of five candidate gun steels. The numerical fits will be employed in subsequent work to predict residual stresses and fatigue lifetimes for autofrettaged tubes manufactured from the candidate steels.

Springback of Copper Alloy Sheets after U-Bending

2014 ◽  
Vol 510 ◽  
pp. 118-122 ◽  
Author(s):  
Hiroshi Hamasaki ◽  
Yasuhiro Hattori ◽  
Kingo Furukawa ◽  
Fusahito Yoshida
Keyword(s):  
Copper Alloy ◽  
Bauschinger Effect ◽  
Kinematic Hardening ◽  
Alloy Sheet ◽  
Isotropic Hardening ◽  
Hardening Model ◽  
Cyclic Tension ◽  
Cold Rolled ◽  
Simulation Results ◽  
Strain Responses

Springback after U-bending of Cu-Ni-Si alloy sheet and cold-rolled brass sheets (JIS C2600R-H and C2600R-1/4H) was calculated by using FEM. In the simulations, the Yoshida-Uemori kinematic hardening model was employed, by which stress-strain responses under uniaxial tension and cyclic tension-compression loadings are accurately described. The simulation results using Yoshida-Uemori model well predicted the experimentally obtained springback, while the isotropic hardening model underestimated it for every material. From such comparisons between experiment and simulation, it is concluded that the Bauschinger effect as well as the plastic strain dependency on Youngs modulus should be taken into account for an accurate springback simulation.

Modeling and Identification of Elastic-Plastic Systems Using the Distributed-Element Model

1997 ◽  
Vol 119 (4) ◽  
pp. 332-336 ◽  
Author(s):  
Dar-Yun Chiang
Keyword(s):  
Distribution Function ◽  
Bauschinger Effect ◽  
Biaxial Tension ◽  
Kinematic Hardening ◽  
Element Model ◽  
Strength Distribution ◽  
Experimental Results ◽  
Modeling Technique ◽  
Elastic Plastic ◽  
Hardening Rules

A modeling technique is proposed for a class of distributed-element models, which is able to account for the multi-axial Bauschinger effect without any additional kinematic hardening rules. The parameters associated with each of the elements in the model are specified by introducing an appropriate strength distribution function so as to make the model parsimonious in parameters regardless of the number of elements introduced in the model. Validity of the proposed modeling technique, in both modeling and identification of elastic-plastic systems, is demonstrated by biaxial tension-torsion applications using experimental results from the literature.

Pertinence of the Grain Size on the Mechanical Strength of Polycrystalline Metals

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
N. A. Zontsika ◽  
A. Abdul-Latif ◽  
S. Ramtani
Keyword(s):  
Grain Size ◽  
Mechanical Strength ◽  
Kinematic Hardening ◽  
Uniaxial Stress ◽  
Isotropic Hardening ◽  
Ultrafine Grained ◽  
Consistent Model ◽  
Micromechanical Approach ◽  
Interaction Law ◽  
Small Deformations

Motivated by the already developed micromechanical approach (Abdul-Latif et al., 2002, “Elasto-Inelastic Self-Consistent Model for Polycrystals,” ASME J. Appl. Mech., 69(3), pp. 309–316.), a new extension is proposed for describing the mechanical strength of ultrafine-grained (ufg) materials whose grain sizes, d, lie in the approximate range of 100 nm < d < 1000 nm as well as for the nanocrystalline (nc) materials characterized by d≤100 nm. In fact, the dislocation kinematics approach is considered for characterizing these materials where grain boundary is taken into account by a thermal diffusion concept. The used model deals with a soft nonincremental inclusion/matrix interaction law. The overall kinematic hardening effect is described naturally by the interaction law. Within the framework of small deformations hypothesis, the elastic part, assumed to be uniform and isotropic, is evaluated at the granular level. The heterogeneous inelastic part of deformation is locally determined. In addition, the intragranular isotropic hardening is modeled based on the interaction between the activated slip systems within the same grain. Affected by the grain size, the mechanical behavior of the ufg as well as the nc materials is fairly well described. This development is validated through several uniaxial stress–strain experimental results of copper and nickel.

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