| Abstract: | Typical fracture surfaces are examined for polymethyl methacrylate specimens subjected to multicycle fatigue testing in circular cantilever bending at T=20, 40, and 60°C. It is established that the fatigue life of smooth specimens is very closely correlated with the size of the diffuse fracture zone. The kinetics of damage accumulation with increase in the number of cycles are investigated by rapidly fracturing prefatigued specimens. The decisive role of diffuse fracture in the fatigue-fracture process is demonstrated. A method of estimating the mean main crack propagation velocity in circular bending is described.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 6, pp. 984–990, November–December, 1973. |
