Influence of Plastic Straining on a Yield Criterion

Abstract

<p> A yield criterion depending on stress, strain and their histories is revised so as to achieve better correlation with experimental data. It is shown that this simple criterion exhibits a reasonable Bauschinger effect. Theoretical expressions for revised yield stresses for two different types of tests are derived for this function. </p> <p> The purpose of the experimental work in this thesis was to determine the degree of correlation between the proposed function and experimental data. Two types of tests were carried out. The first test was essentially for evaluating the constants appearing in the yield criterion. These values of constants were then used to predict the gross tensile stress-strain curves for specimens cut from sheets which had undergone plastic bending in one direction and contained residual stresses prior to tensile loading. An approximate method to calculate these residual stresses is also outlined. </p> <p> Conclusions are deduced by comparing the experimental and theoretical results for these tests and suggestions are made for future research. </p>