Modeling of Strength Differential Effects in HCP Sheet Materials

2014 ◽  
Author(s):  
Srihari Kurukuri ◽  
Michael Worswick
Keyword(s):  
Principal Stress ◽  
Yield Locus ◽  
Uniaxial Tensile ◽  
Stress Space ◽  
Strength Differential ◽  
Finite Element Software ◽  
Symmetric Plane ◽  
Yield Functions ◽  
Hcp Materials ◽  
Principal Stress Space

A simple approach is proposed to employ symmetric yield functions for modeling the tension-compression asymmetry commonly observed in hcp materials. In this work, the strength differential (SD) effect is modeled by choosing separate symmetric plane stress Barlat Yld 2000 yield functions for the tension i.e., in the first quadrant of principal stress space, and compression i.e., third quadrant of principal stress space. In the second and fourth quadrants, the yield locus is constructed by adopting Bézier interpolating functions between uniaxial tensile and compressive stress states. The main advantage of this proposed approach is that the yield locus parameters are deterministic and relatively easy to identify when compared to the Cazacu-Plunkett-Barlat (CPB) family of yield functions commonly used for modeling the SD effect observed in hcp materials. The proposed yield function is implemented as a user material subroutine (UMAT) within the commercial finite element software, LS-DYNA. The predictions of the developed material model are compared with the measured load-displacement and strain distributions from a three-point bend experiment on AZ31B sheet.

Discussion on the Use of Parameters of Drucker-Prager Criterion

2006 ◽  
Vol 306-308 ◽  
pp. 1449-1454 ◽  
Author(s):  
Shui Lin Wang ◽  
Yu Yong Jiao ◽  
Haibin Xiao ◽  
Chun Guang Li
Keyword(s):  
Principal Stress ◽  
Yield Criterion ◽  
Elastoplastic Analysis ◽  
Computational Results ◽  
Stress Space ◽  
Engineering Problems ◽  
Principal Stress Space ◽  
Yield Surfaces ◽  
Coulomb Criterion

There are several different yield surfaces of Drucker-Prager yield criterion which corresponds to Mohr-Coulomb yield criterion in principal stress space. The different yield surfaces are determined by parameters in Drucker-Prager criterion. The influence of the different parameters on computational results is discussed in the paper, and the use of the equivalent Drucker-Prager criterion to Mohr-Coulomb criterion is suggested when elastoplastic analysis is performed in engineering problems.

Positive and Negative Failure-Shears in Orthotropic Materials

1992 ◽  
Vol 11 (1) ◽  
pp. 32-55 ◽  
Author(s):  
P. S. Theocaris
Keyword(s):  
Principal Stress ◽  
Failure Criterion ◽  
Fiber Composite ◽  
Pure Shear ◽  
Failure Surface ◽  
Loading Path ◽  
Orthotropic Materials ◽  
Stress Space ◽  
Elliptic Paraboloid ◽  
Principal Stress Space

Failure predictions of off-axis loaded fiber composite laminae are given according to the elliptic paraboloid failure criterion for anisotropic solids [1]. The failure condition assumes that for any anisotropic solid a safe triaxial loading path exists, along the hydrostatic compression, and thus the failure surface must be open-ended. By appropriately formulating the failure criterion, it is shown that the geometric interpretation of the failure surface in the principal stress space is an elliptic paraboloid (EPFS) whose axis of symmetry is parallel to the hydrostatic axis in the principal stress space. Because of the shape and position of the EPFS, the intersections by principal stress planes corresponding to loadings of off-axis laminae of a fiber composite are represented by ellipses whose origins are displaced from the origin of the stress reference frame. This fact creates unequal shear yield stresses in the positive and negative sense clearly manifested in a pure shear failure loading. The predictions of the above criterion for plane stress failure loadings of laminae, and especially for pure shear induced failures, are compared with existing experimental data for various fiber composites and are shown to be in satisfactory agreement.

Mögliche Deutungen quadratischer Fließbedingungen bei Isotropie und Anisotropie / Physical Interpretations of Isotropic and Anisotropic Yield-Conditions

1975 ◽  
Vol 30 (8) ◽  
pp. 996-1000
Author(s):  
A. Troost ◽  
J. Betten
Keyword(s):  
Shear Stress ◽  
Principal Stress ◽  
Yield Criterion ◽  
Physical Significance ◽  
Stress Space ◽  
Physical Explanation ◽  
Principal Stress Space ◽  
Anisotropic Yield Criterion ◽  
The Difference ◽  
Yield Conditions

Abstract The paper introduces shear stress quantities, which are the difference of two stress tensors, the actual one and one produced by rotating the axes. This quantities have physical significance. In the vectorial representation in the principal stress space and the principal shear stress space the paper give some interesting relations. The authors observe that Hill′s anisotropic yield criterion can be derived from their shear stress quantities by introducing a measure tensor and gave a physical explanation to Hill′s condition.

Convexity studies of two anisotropic yield criteria in principal stress space

1999 ◽  
Vol 16 (2) ◽  
pp. 215-229 ◽  
Author(s):  
Pankaj ◽  
Mohammed Arif ◽  
Surendra K. Kaushik
Keyword(s):  
Principal Stress ◽  
Stress Space ◽  
Yield Criteria ◽  
Principal Stress Space
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