Prediction of the slope discontinuity in stress-strain behaviour of polymeric composites with spherical inclusions

Abstract

The estimation of the point of discontinuity in the slope of stress-strain curves (commonly referred to as "knee") generally observed with composite polymeric materials could be an important problem for the specific application of the composite items. In this work, we have used the results from classical elasticity theory to calculate the residual thermal stresses and proposed simplifying assumptions to calculate a "lower bound" on the applied stress value at which the "knee" can occur. The theoretical predictions have been then compared with the experimental data on various polymeric composites containing glass beads and the agreement is found to be very sound. The proposed equation can be reliably used in engineering design.