Abstract
The change of the dynamic viscoelaticity during the fatigue process and the fracture surface phases were investigated to the fatigue fracture mechanism of PC and PMMA at high temperature in this study. The results are following as : (1) For the dynamic viscoelaticity testing, PC is heat-resistant materials because the change of E' was little from low temperature to high temperature of 140°C, however, PMMA is a sensitive materials to the temperature change. (2) For the tensile testing, PMMA comparing with PC was very large on the initial elasticity and low strain stress companion to the increase of temperature, therefore, PC is a ductile materials and PMMA is a brittle materials. (3) PMMA was more than PC on the low fatigue life due to the increase in testing temperature. Because there was an angle between the load direction and the crack propagation, the ductile fracture of PC took place in the part section. There was no change for the fatigue life of PC on the increase in the stress amplitude. (4) The fatigue fracture mechanism of PC is the same as that of PMMA at each temperature. There are closely relationship with the fatigue process of E' and the change trend of tan δ as well as the characteristic of the fracture surface.
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