Multiaxial ratcheting modeling with incorporation of a yield surface distortion model

2016 ◽  
Vol 231 (6) ◽  
pp. 979-994 ◽  
Author(s):  
H Rokhgireh ◽  
A Nayebi
Keyword(s):  
Cyclic Loading ◽  
Yield Surface ◽  
Cyclic Plasticity ◽  
Stress Strain ◽  
Distortion Model ◽  
Surface Distortion ◽  
Ratcheting Strain ◽  
Proposed Model ◽  
Strain Paths ◽  
Yield Surface Distortion

Correct determination of ratcheting strain is very important in cyclic loading. A new simple yield surface distortion model is presented and its effect on cyclic loading and ratcheting prediction is investigated in this research. Model of Baltov and Sawczuk was modified in order to be able to consider directional distortion of the yield surface. Movement of the yield surface center is modeled by Chaboche's nonlinear kinematic hardening model. Isotropic hardening was also considered. A triangular function is used and necessary cyclic plasticity relations are developed. Convexity of the proposed model is discussed and verified. Performance of the proposed model in ratcheting strain prediction is investigated in multiaxial non proportional loadings under different paths. Experimental results with stress, strain and combined stress-strain control paths are compared with the proposed model results. Incorporation of the yield surface distortion of this new model, predicts better ratcheting strain for different stress, strain and stress-strain paths.

Cyclic Plasticity for Nonproportional Paths: Part 2—Comparison With Predictions of Three Incremental Plasticity Models

1978 ◽  
Vol 100 (1) ◽  
pp. 104-111 ◽  
Author(s):  
H. S. Lamba ◽  
O. M. Sidebottom
Keyword(s):  
Cyclic Loading ◽  
Material Property ◽  
Yield Surface ◽  
Strain Path ◽  
Kinematic Hardening ◽  
Cyclic Plasticity ◽  
Limit Surface ◽  
Hardening Rule ◽  
Hardening Models ◽  
Hardening Rules

Experiments that demonstrate the basic quantitative and qualitative aspects of the cyclic plasticity of metals are presented in Part 1. Three incremental plasticity kinematic hardening models of prominence are based on the Prager, Ziegler, and Mroz hardening rules, of which the former two have been more frequently used than the latter. For a specimen previously fully stabilized by out of phase cyclic loading the results of a subsequent cyclic nonproportional strain path experiment are compared to the predictions of the above models. A formulation employing a Tresca yield surface translating inside a Tresca limit surface according to the Mroz hardening rule gives excellent predictions and also demonstrates the erasure of memory material property.

A Fast Method for Ratchetting Strain Prediction

2006 ◽  
Author(s):  
Mohammad Noban ◽  
Hamid Jahed
Keyword(s):  
Cyclic Loading ◽  
Single Step ◽  
Frame Of Reference ◽  
Cyclic Plasticity ◽  
Moving Frame ◽  
Fast Method ◽  
Proportional Loading ◽  
Proposed Model ◽  
Cyclic Plasticity Model ◽  
Deviatoric Stresses

A time efficient method for predicting ratchetting strain is proposed. By finding the ratchetting rate, at only a few cycles, the ratchetting strain of any cycle can be determined. It is shown that a trajectory of the origin of stress may be defined in the deviatoric stress space as the ratchetting progresses. The method for obtaining this trajectory from a standard uniaxial asymmetric cyclic loading is presented. At the beginning, this trajectory coincides with the initial stress origin and approaches the mean stress, displaying a power law relationship with the number of loading cycles. This path defines a moving frame of reference for stress tensor calculations. Ratchetting rates for different cyclic loading are calculated with the knowledge of this frame of reference and through utilizing a constitutive cyclic plasticity model which incorporates deviatoric stresses and back stresses that are measured with respect to this moving frame. The proposed model is used to predict ratchetting strain of 1070 steel under single step constant amplitude and multi-step loading. The method is also applied to non-proportional loading. Results obtained agree with the available experimental measurements.

A Theory of Multiaxial Anisotropic Viscoplasticity

1981 ◽  
Vol 48 (2) ◽  
pp. 276-284 ◽  
Author(s):  
M. A. Eisenberg ◽  
C.-F. Yen
Keyword(s):  
Yield Surface ◽  
Stress Space ◽  
Anisotropic Hardening ◽  
Surface Distortion ◽  
Induced Changes ◽  
Yield Surface Distortion

A theory of anisotropic viscoplasticity is developed. It is compared with and shown to reduce to existing theories under appropriate restrictions. The theory accommodates anisotropic hardening laws which, by means of Lagrangian mappings in stress space, incorporate experimentally observed yield surface distortion as well as kinematic and isotropic flow-induced changes. The theory is applied to the prediction of flow surfaces in tension-torsion space.

A New Model to Describe Yield Surface Distortion Based on the Baltov and Sawczuk’s Model

2012 ◽  
Author(s):  
A. Nayebi ◽  
H. Rokhgireh
Keyword(s):  
Yield Surface ◽  
Kinematic Hardening ◽  
Experimental Results ◽  
Surface Model ◽  
New Model ◽  
Surface Distortion ◽  
Loading Direction ◽  
Reverse Loading ◽  
Reversed Loading ◽  
Yield Surface Distortion

In the present study Baltov and Sawczuk’s yield surface model is modified to represent compatible results with experimental observations. The proposed yield surface is determined during tension-torsion loading by considering kinematic hardening model and monotonic loading paths. The experimental results represent the nosed and flattened region in the loading and reverse loading direction respectively. The nosed region is dominant in tension than in torsion. The cross-effect is negligible in the small plastic strain amount. The Baltov and Sawczuk’s yield surface has nosed and flattened regions in both loading and reversed loading directions for negative and positive added material parameter respectively. Thus the elliptic Baltov and Sawczuk’s yield surface is modified by changing the sign of this parameter continuously from loading to reverse loading direction and the needed relations of the new model are obtained. The new model was able to predict properly the shape of yield surface. The experimental results compare well with the new model yield surface distortion predictions.

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