| Abstract: | Instantaneous crack resistance values during the mode I stable crack propagation in poly(methyl methacrylate) (PMMA) were investigated with the aid of the sector area method at different test temperatures. The crack resistance during stable crack propagation is a gradually decreasing function of crack passage at all temperatures. The rate decreases as the test temperature decreases, down to ?30°C, irrespective of high initial crack resistance. The crack propagation velocity profiles, obtained through velocity gages, also show the decreasing function of crack passage. Both crack resistance R and its gradient with respect to the crack propagation velocity, dR/d?, become greater as the temperature decreases. R becomes greater as ? increases, contrary to the usual crack resistance behavior in metals. |
