Abstract
Investigations have been carried out to study the behaviour of polycrystalline copper under alternating stress in the intermediate life range. Continuous hardening has been observed throughout the life. The average plastic strain is related to the stress amplitude by a power law with the cyclic strain hardening coefficient n′=0.24. The Manson-Coffin law is obeyed in this life range also, with the fatigue ductility exponent C=−0.53. The product of alternating stress and plastic strain is found to be proportional to the hysteresis energy absorbed during each cycle. The total hysteresis energy absorbed is not a material constant, but increases with decreasing values of the alternating stress and consequently increases with increasing fatigue life.
