Shear Lip Formation Research Articles

Gc versus crack velocity in single groove double cantilever beam specimens of polycarbonate

The dependence of Gc on crack velocity in single-groove double cantilever beams (SG DCB) is negligible over the range of crack velocities from 0.2 to 1100 in. min−1. The constancy of Gc appears to reflect a counterbalancing of the rise in yield stress by a decrease in crack opening displacement. The latter occurs through a decrease in the “gauge length” of material engulfed by yielding rather than by a decrease in the ultimate plastic strain in the crack tip plastic zone. The energy of shear lip formation at any crack velocity appears to be accurately estimated from Gc's for SG DCB specimens fractured at low velocity.