Experimental studies on the uniaxial ratchetting of polycarbonate polymer at different temperatures

A series of uniaxial stress-controlled cyclic tests were carried out at different temperatures to investigate the uniaxial ratchetting of polycarbonate (PC) and its time-dependent behavior. The cyclic tests were conducted with a constant peak stress, various valley stresses and at four prescribed temperatures (i.e., 0, 30, 60 and 90°C). The effects of applied valley stress and ambient temperature on the uniaxial ratchetting of the PC are discussed. From the experimental observations, it is concluded that the ratchetting of the PC depends greatly on the test temperature; both the ratchetting strain and ratchetting strain rate increase with increase of test temperature. The effect of different valley stresses on the ratchetting is also dependent on the test temperatures, and fatigue rupture occurs in the load cases with negative valley stresses and at higher temperatures.