A strain energy density based lifetime prediction model for notched specimens: Case of polycarbonate under thermal fatigue

摘要

Polycarbonate is more and more used in engineering because of its good mechanical properties. Pieces in polycarbonate are used in environments of variable temperatures, especially, in electronic devices. Thermal stresses could become importantand, for this reason, effects of thermal stresses must be taken into account in designing pieces in polycarbonate. The method proposed to predict the life of notched test specimens is bated on the dissipated strain energy density. behaviour laws ofpolycarbonate at various temperatures are determined, and fatigue tests on smooth specimens give us the thermal fatigue laws of the material. Fatigue tests on notched specimens and FEM computation give us a relation between the stress concentrationfactor, the strain energy density dissipated in notch roots, and the nominal strain energy density. A life prediction model is proposed and discussed.