ANALYSIS OF DYNAMIC CREEP CONSIDERING STRAIN RATE EFFECTS

摘要

The dynamic creep behavior of a number of materials is discussed and classified. The creep properties under simultaneous action of static stress and alternating stress have been derived by several authors from the creep rate-stress relationship under static load. The use of this so derived stress range diagram for creep as a basis for determination of acceleration or retardation of dynamic creep is emphasized. Retardation of creep is attributed to aging effects, and to strain rate effects caused by alternating stress frequency. Acceleration of creep is attributed to metallurgical changes, and over temperature at very high frequencies. Special consideration is given to the effect of superposition of strain rate and creep rate. The theoretical analysis of the strain rate effects in dynamic creep, presented here, conform with the experimental observation that retardation of creep increases with increasing temperature, and with increasing alternating stress frequency if metallurgical effects are negligible.