Residual stresses in codeformed composite cylinders

The compatibility of materials deformed simultaneously and homogeneously depends to a great extent on the residual stresses remaining after the forming process is complete. A procedure is described for the calculation of such stresses arising from both the mutual elastic constraints exerted on components and the thermal expansion mismatch resulting from cooling from the forming temperature. The procedure is illustrated by an analysis of the dependence of residual stresses at the interface of coextruded rods of copper-clad aluminum as a function of core volume fraction at constant extrusion ratio and on extrusion ratio at constant core volume fraction. The state of stress can be significantly altered by the choice of composite composition and extrusion ratio.