Modelling hot plane strain compression test Part 3 – Effect of asymmetric conditions

Abstract

Finite element analysis has been used to study possible causes of asymmetrical deformation in plane strain compression tests and their consequences. It is shown that U shaped or Z shaped distortion of the specimens can arise from temperature gradients, lateral offset of the tools and non-uniform lubrication, which causes different coefficients of friction at the top and bottom tools, or a changing coefficient of friction across the width of the tools. When the tools are rigid, the stress–strain curves are the same as for specimens deformed symmetrically under the same mean, but uniform conditions. With changing friction conditions across the width of the tools, the lateral load generated can be sufficiently large to cause lateral displacement of the tools in experimental practice. Computation with the top tool free to rotate leads to severe asymmetry and a small reduction in the level of the stress–strain curve.