Fatigue Reliability and Fatigue Mode above Glass Transition Temperature for Carbon Fiber Reinforced PEEK : On Self-Heating and Meso Crack Forming Concerned with Thermal and Mechanical Fatigue

Abstract

The estimation of fatigue reliability and fatigue mode above glass transition temperature (T_g) for earbon fiber reinforced PEEK was conducted. Self-heating and meso crack forming concerned with thermal and mechanical fatigue was focused on. The main results are as follows, (1) It was recognized that the fatigue characteristics of test pieces above T_g differed from those under T_g. Thus, the influence of environmental temperature on fatigue characteristics was arranged by 'S-N globe'. (2) The fatigue mode at elevated temperatures was divided into two mechanisms. One was thermal fatigue for short fatigue life, the other was mechanical fatigue for long fatigue life. (3) In the case of thermal fatigue, fracture surface was ductilc and self-heating was large : in the case of mechanical fatigue, the former was brittle and the latter was small. (4) The roles of carbon fiber were to constrain the deformation of matrix on thermal fatigue, and to control meso crack forming on mechanical fatigue.