Abstract
Tensile and fatigue tests under the conditions of various testing speeds and temperatures have been performed on a thermoplastic resin (polyacetal) to investigate the effects of testing speed and temperature on its tensile and fatigue properties.
The results obtained are:
(1) The static tensile strength increases with strain rate but decreases with temperature due to softening.
(2) The fatigue strength decreases with increase of frequency and temperature due to softening as a result of heat generation by fatigue stressing.
(3) The variation (increase) of deflection during fatigue stressing is similar to that of surface temperature of the specimen.
(4) The relation between the initial deflection and the number of cycles to fracture is represented by a curve regardless of testing temperature.
(5) Softening as a result of heat generation due to repeated stressing contributes largely to the fatigue fracture of the material.
