Abstract: On the basis of the alternating load function of the thermal load-mechanical load on position of gasoline, the Palmgrem-Mine accumulative invalidation principle is carried out to analyze the characteristic of position failure and test the life of nodes of the piston ring groove bottom using the FE method and the principles of stress amplitude-mean stress distributing and the Palmgrem-Mine principle. It is showed that the failure of position is the effect of the alternating thermal load and the alternating mechanical load and because of superposition of high thermal load and alternating mechanical load. Expecting the thermal stress and mechanical stress, the cycle fluctuating thermal stress and creep material and process existing in the first annular groove is also the cause of the fail-ure.

Key words: Breakage, Accumulative invalidation, Alternating load, Piston ring bank