Modifications du coefficient d’anisotropie plastique en cours de déformation hétérogène

Modification of the coefficient of plastic anisotropy at the inhomogeneous deformation.

Institut de Recherches métallurgiques Académie polonaise des Sciences, Cracovie

Abstract

A method has been proposed for the determination of the parameters of functions limiting the interval of the experimental scatter relative to the function expressing the variation of the coefficient of anisotropy r in the tensile test. For this aim, it is indispensable to know the c (ε) relation yielding the characteristics of the experimental error in the tensile test.

In the case of macrohomogeneous deformation, the zone of scatter of experimental results, more expanded on the side of low elongations, diminishes quickly with the strain. The macroinhomogeneous deformation is responsible for a remarkable scatter which manifests itself also at medium values of strain, and still increases within the zone of high strains.

An analysis of the results of experiments carried out on copper has shown that with the aid of the formulas deduced by the present authors it is possible to describe with sufficient precision the experimental scatter accompanying the r (ε) function when starting from two constant parameters which caracterize the initial state of the test-piece and inhomogeneity of deformation.

The present paper opens new perspectives for the elaboration of a formal method determining the ra value by extrapolation of the r (ε) function to ε = 0.