Constrained Elastic-Plastic Materials

1994 ◽  
Vol 61 (3) ◽  
pp. 511-518 ◽  
Author(s):  
H. C. Lin ◽  
P. M. Naghdi
Keyword(s):  
Detailed Examination ◽  
Stress And Strain ◽  
Response Functions ◽  
Elastic Plastic ◽  
Plastic Materials ◽  
Yield Functions ◽  
Space Formulation ◽  
Elastic Plastic Materials ◽  
Strain Space

The main purpose of this paper is to present a general (purely mechanical) constrained theory of finitely deforming elastic-plastic materials. Our development is based on a strain-space formulation of plasticity and requires a detailed examination of the effect of constraint on various constitutive ingredients in the unconstrained theory, including the yield functions (in both the stress and strain spaces), the loading criteria, and various response functions. Also examined is the effect of constraint on the restrictions arising from the work inequality of Naghdi and Trapp (1975b).

On the Characterization of Strain-Hardening in Plasticity

1981 ◽  
Vol 48 (2) ◽  
pp. 285-296 ◽  
Author(s):  
J. Casey ◽  
P. M. Naghdi
Keyword(s):  
Strain Hardening ◽  
Plastic Behavior ◽  
Hardening Behavior ◽  
Perfectly Plastic ◽  
Plastic Materials ◽  
Space Formulation ◽  
Elastic Plastic Materials ◽  
Strain Hardening Behavior ◽  
Strain Space

In the context of a purely mechanical, rate-type theory of elastic-plastic materials and utilizing a strain space formulation introduced in [1], this paper is concerned mainly with developments pertaining to strain-hardening behavior consisting of three distinct types of material response, namely, hardening, softening, and perfectly plastic behavior. It is shown that such strain-hardening behavior may be characterized by a rate-independent quotient of quantities occurring in the loading criteria of strain space and the corresponding loading conditions of stress space. With the use of special constitutive equations, the predictive capability of the results obtained are illustrated for strain-hardening response and saturation hardening in a uniaxial tension test.

On Determining Elastic Modulus from Instrumented Indentation

2013 ◽  
Vol 668 ◽  
pp. 616-620
Author(s):  
Shuai Huang ◽  
Huang Yuan
Keyword(s):  
Finite Element ◽  
Elastic Modulus ◽  
Plastic Material ◽  
Instrumented Indentation ◽  
Computational Simulations ◽  
Elastic Plastic ◽  
Modified Method ◽  
Plastic Materials ◽  
Elastic Plastic Material ◽  
Elastic Plastic Materials

Computational simulations of indentations in elastic-plastic materials showed overestimate in determining elastic modulus using the Oliver & Pharr’s method. Deviations significantly increase with decreasing material hardening. Based on extensive finite element computations the correlation between elastic-plastic material property and indentation has been carried out. A modified method was introduced for estimating elastic modulus from dimensional analysis associated with indentation data. Experimental verifications confirm that the new method produces more accurate prediction of elastic modulus than the Oliver & Pharr’s method.

The Propagation of Plasticity in Uniaxial Compression

1948 ◽  
Vol 15 (3) ◽  
pp. 256-260 ◽  
Author(s):  
M. P. White ◽  
LeVan Griffis
Keyword(s):  
Uniaxial Compression ◽  
Thin Sheet ◽  
High Stress ◽  
Stress And Strain ◽  
Velocity Range ◽  
Plastic Materials ◽  
The Face ◽  
Elastic Plastic Materials ◽  
The Impact ◽  
Type Of Behavior

Abstract A theoretical investigation of the mechanism of uniaxial compression impact on elastic-plastic materials is described in this paper. The method of analysis is similar in some respects to that previously given for tension impact on such materials. It is concluded that four different kinds of behavior can occur, depending upon the impact velocity. In the lowest velocity range the behavior in compression is similar to that found in tension. In this case stress and strain are propagated from the point of impact as a zone or wave front of ever-increasing length. This type of behavior ends at a velocity corresponding to the “critical” velocity found in tension impact. Within the next higher velocity range, stress and strain are propagated as a shock-type wave, or wave of very small length in which the transition from low to high stress and strain is very abrupt. At still higher impact velocities, there occurs “flowing deformation” in which the material is too weak to maintain coherency. Here there is a steady flow of the material toward and against the hammer, after which it flows in a thin sheet radially outward over the face of the hammer. The final possible state occurs at impact velocities greater than the speed of an elastic wave, so that no disturbance can escape from the hammer into the medium. Here the behavior is essentially that of a fluid, impact force being independent of strength of material.

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