Design method of imitation specimen for engine disk with any maximum stress gradient path

A design criteria of disk two-dimensional(2-D) imitation specimen based on stress-life was established.The imitation specimen's optimum design methods about random maximum stress gradient were proposed,including: searching automatically the maximum first principle stress gradient route,stress distribution and two-stage optimization method of the imitation specimen.An equivalence principle of elastic and plastic design for the imitation specimen was proposed based on the analysis of examples.