The limiting state of force systems and processes of damage of them. Report 1. Energy criteria of failure

A composite energy criterion of failure of a force system in relation to test temperature and level of normal and frictional stresses is proposed and a method has been developed for separation from the full mechanical and thermal energy of their effective portions expended on formation and accumulation of damages. The concept has been introduced of the parameters of interaction of different constituents of the effective energy and a method is given for evaluation of them. Particular criteria of thermal force failure have been obtained and understandings of the limits of (mechanical) destruction and of temperature destruction have been introduced. On the basis of experimental results satisfactory correspondence to the test data of the thermal force criterion in the 4 K to T _melt range has been established for nickel and aluminum and an analysis has also been made of the change in mechanisms of damage of these materials in connection with varying of the level of stresses and test temperature.Translated from Problemy Prochnosti, No. 1, pp. 11–23, January, 1993.