Yield and Flow Behavior of Initially Anisotropic Aluminum Tube Under Multiaxial Stresses

1993 ◽  
Vol 115 (1) ◽  
pp. 77-82 ◽  
Author(s):  
Takenobu Takeda
Keyword(s):  
Stress Field ◽  
Internal Pressure ◽  
Principal Stress ◽  
Yield Surface ◽  
Flow Behavior ◽  
Yield Function ◽  
Strain Behavior ◽  
Anisotropic Yield Function ◽  
Initial Anisotropy ◽  
Von Mises

By means of combining Drucker’s yield function with Hill’s quadratic yield function, an anisotropic yield function of the sixth degree is proposed. It is able to include the effects of the third deviatoric stress invariant and initial anisotropy. Experiments are carried out on fully annealed 1050 aluminum tubes under multiaxial stress states. By applying proportional loadings of axial load, internal pressure and torsion to the specimens, the change in yield stress with a rotation of the principal stress axes and the difference between the directions of the principal stress and principal strain increment are examined. The yield surface in the tension-internal pressure stress field reveals orthotropic anisotropy. The yield surface in the tension-torsion stress field lies outside von Mises’ yield surface. Such behavioral characteristics can be expressed precisely by the proposed yield function. In addition, it is experimentally verified that the normality rule is obeyed in strain behavior.

An Investigation of Yield Potentials In Superplastic Deformation

1999 ◽  
Vol 122 (1) ◽  
pp. 93-97 ◽  
Author(s):  
Marwan K. Khraisheh
Keyword(s):  
Effective Strain ◽  
Yield Function ◽  
Yield Potential ◽  
Anisotropic Yield Function ◽  
Superplastic Alloy ◽  
Degree Of Anisotropy ◽  
Anisotropic Function ◽  
Experimental Yield ◽  
Dynamic Yield ◽  
Von Mises

Recent results (Khraisheh et al., 1995 and 1997) have indicated that superplastic materials exhibit a strong degree of anisotropy and that the plastic flow cannot be described by the isotropic von Mises flow rules. In this study, the yield potential for the model Pb-Sn superplastic alloy is constructed experimentally for different effective strain rates using combined tension/torsion tests. A generalized anisotropic “dynamic” yield function is also proposed to represent the experimentally constructed yield potentials. The anisotropic function is not only capable of describing the initial anisotropic state of the yield potential, it can also describe its evolution through the evolution of unit vectors defining the direction of anisotropy. The anisotropic yield function includes a set of material constants which determine the degree of deviation of the yield potential from the isotropic von Mises yield surface. It is shown that the anisotropic yield function successfully represents the experimental yield potentials, especially in the superplastic region. [S0094-4289(00)01401-8]

Plastic Stress-Strain Relationships—Further Experiments on the Effect of Loading History

1961 ◽  
Vol 28 (3) ◽  
pp. 439-446 ◽  
Author(s):  
J. Parker ◽  
J. Kettlewell
Keyword(s):  
Internal Pressure ◽  
Yield Surface ◽  
Yield Function ◽  
Loading History ◽  
Cross Effect ◽  
Stress Strain ◽  
Loading Paths ◽  
Degree Of Anisotropy ◽  
Alpha Brass ◽  
Plastic Stress

Further tests have been carried out on thin closed-ended tubes of alpha brass subjected to various combinations of torque and internal pressure. The effect of loading, unloading, and reloading along different paths has been investigated. The loading paths were based on a yield function which has previously been found to correlate initial radial loadings for this material, which possesses one degree of anisotropy. However, the results obtained from the second loadings suggest a cross effect which is greater than would be obtained from a nested set of yield surfaces of the foregoing form. There appears to be no evidence to support the presence of a corner in the yield surface.

A Consistent Criterion for Diffuse Necking in Sheet Metals Using Hill’s 1979 Yield Surface

1998 ◽  
Vol 120 (2) ◽  
pp. 177-182 ◽  
Author(s):  
S. K. Esche ◽  
R. Shivpuri
Keyword(s):  
Plastic Deformation ◽  
Yield Surface ◽  
Shape Factor ◽  
Biaxial Tension ◽  
Yield Function ◽  
Surface Shape ◽  
Principal Strain ◽  
Sheet Metals ◽  
Diffuse Necking ◽  
Anisotropic Yield Function

A review of some existing criteria for diffuse necking in sheet metals is given and their limitations are discussed. The introduction into production of new sheet materials whose plastic deformation is impossible to be modeled using Hill’s 1948 anisotropic yield function necessitates improvements of these existing criteria to accurately describe their necking behavior. In this paper, a generalization of the existing diffuse necking criteria for materials describable by Case IV of Hill’s 1979 anisotropic yield function is presented. The proposed criterion is consistent with the previous criteria. It predicts a significant effect of Hill’s 1979 yield surface shape factor on the critical principal strain in the range of negative minor strains while in the range of biaxial tension this influence is small.

Effects of the Yield Criterion on Predicted Fracture Responses of Pipelines Subjected to Large Plastic Deformation With and Without Internal Pressure

2010 ◽  
Author(s):  
Alexandre Kane ◽  
Erling O̸stby ◽  
Odd-Geir Lademo ◽  
Torodd Berstad ◽  
Odd Sture Hopperstad
Keyword(s):  
Internal Pressure ◽  
Yield Surface ◽  
Structural Integrity ◽  
Yield Criterion ◽  
Surface Shape ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Safety Level ◽  
Standard Material ◽  
Von Mises

The structural integrity of offshore pipelines is of vital importance for safe oil and gas transport. To ensure the required safety level, non-linear Finite Element (FE) analyses are necessary to perform fracture assessment of pipes under various, realistic loading conditions. Many standard material models, as found in commercial FE codes, pre-suppose the yield criterion of von Mises. This choice provides in many cases reasonable accuracy, certainty and engineering designs, but for some materials and application areas, it is much too inaccurate. In this work, 3D elastic–plastic FE simulations of pipes with internal surface cracks have been carried out. The aim of the work is to evaluate the influence of the yield criterion on the predicted fracture response. Analyses are performed on pipes loaded in tension, with and without internal pressure. The model shows that the yield surface shape may have a significant effect on the predicted evolution of Crack Tip Opening Displacement (CTOD). If the internal pressure is weak, a reduction in strain capacity is observed when the yield surface shape is varied from the rounded von Mises towards the cornered Tresca-like yield surface.

Yield Surface for Grey Cast Iron Under Biaxial Stress

1994 ◽  
Vol 116 (2) ◽  
pp. 148-154 ◽  
Author(s):  
H. E. Hjelm
Keyword(s):  
Cast Iron ◽  
Plane Stress ◽  
Yield Surface ◽  
Yield Curve ◽  
Yield Function ◽  
Grey Cast Iron ◽  
Biaxial Stress ◽  
Hardening Modulus ◽  
Grey Cast ◽  
Von Mises

Biaxial plane stress experiments have been performed on cruciform specimens made of graphite grey cast iron. Different ratios of tensile and compressive loads were applied in two perpendicular directions. The primary objective of this investigation is to determine the locus of the yield surface (yield curve) under plane stress, and to establish yield functions that could model the elastoplastic behavior of grey cast iron with reasonably good accuracy. The experiments show that a sufficiently accurate description is obtained by using the ordinary von Mises yield function in the compressive-compressive region, and elsewhere, the von Mises yield function modified with a term containing the first stress invariant. It was also found that for tensile loadings nonelastic deformations develop at low stress levels. Use of the above yield function must therefore be accompanied by a very large hardening modulus for tensile loads.

Elasto-Plastic Analysis of Reissner-Mindlin Plates

1990 ◽  
Vol 43 (5S) ◽  
pp. S40-S50 ◽  
Author(s):  
Panayiotis Papadopoulos ◽  
Robert L. Taylor
Keyword(s):  
Yield Function ◽  
Rate Equations ◽  
Test Problems ◽  
Field Equations ◽  
Element Analysis ◽  
Linear Hardening ◽  
Nonlinear Version ◽  
Plastic Analysis ◽  
Von Mises ◽  
Predictor Corrector

A finite element analysis of elasto-plastic Reissner-Mindlin plates is presented. The discrete field equations are derived from a nonlinear version of the Hu-Washizu variational principle. Associative plasticity, including linear hardening, is employed by means of a generalized von Mises-type yield function. A predictor/corrector scheme is used to integrate the plastic constitutive rate equations. Numerical simulations are conducted for a series of test problems to illustrate performance of the formulation.

Elastic-plastic response of a sandwich cylinder subjected to internal pressure

1971 ◽  
Vol 6 (4) ◽  
pp. 273-278 ◽  
Author(s):  
H F Muensterer ◽  
F P J Rimrott
Keyword(s):  
Mild Steel ◽  
Internal Pressure ◽  
Plastic Flow ◽  
Plastic Response ◽  
Concentric Cylinders ◽  
Initial Stage ◽  
Sandwich Type ◽  
Plastic Zones ◽  
Thin Walled ◽  
Von Mises

The propagation of plastic zones in a thin-walled sandwich-type cylinder has been analysed theoretically. Boundary conditions are clamped-clamped at both ends, i.e. no rotation is permitted. The material was assumed to behave isotropically and to obey the yieid criterion of Huber-Hencky-von Mises. Deformation was computed on the assumption that the vector of rate of strain was normal to the plastic-interaction curve. The predicted result was verified experimentally. Four specimens were built by lamination of a hexcell core between two concentric cylinders. In the two mild-steel specimens, the initial stage of plastic flow conformed well with the prediction. This proved that plastic flow is not initiated at the mid-position between the end constraints. In two aluminium specimens, this phenomenon of incipient plastic flow could not be observed owing to the absence of a pronounced yield point. The overall agreement was, however, satisfactory.

Influence of Anisotropic Yield Functions on Parameters of Yoshida-Uemori Model

2013 ◽  
Vol 554-557 ◽  
pp. 2440-2452 ◽  
Author(s):  
Hirotaka Kano ◽  
Jiro Hiramoto ◽  
Toru Inazumi ◽  
Takeshi Uemori ◽  
Fusahito Yoshida
Keyword(s):  
Effective Strain ◽  
Yield Function ◽  
Strain Response ◽  
Material Parameters ◽  
International Conference ◽  
Polynomial Type ◽  
Calculated Stress ◽  
Yield Functions ◽  
Order Polynomial ◽  
Von Mises

Yoshida-Uemori model (Y-U model) can be used with any types of yield functions. The calculated stress strain response will be, however, different depending on the chosen yield function if the yield function and the effective strain definition are inappropriate. Thus several modifications to Y-U model were proposed in the 10th International Conference on Technology of Plasticity. It was ascertained that in the modified Y-U model, the same set of material parameters can be used with von Mises, Hill’s 1948, and Hill’s 1990 yield function. In this study, Yld2000-2d and Yoshida’s 6th-order polynomial type 3D yield function were examined and it was clarified that the same set of Y-U parameters can be used with these yield functions.

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