Multiaxial fatigue life evaluation method and apparatus

摘要

PROBLEM TO BE SOLVED: To provide a multiaxial fatigue life evaluation method and a device by which necessity of life evaluation in consideration of a non-proportional load is easily determined, and evaluation in consideration of an operational condition and a load path is possible.;SOLUTION: Relation of variation of a value including a direction change of main stress or main distortion to the load path length is calculated based on stress or a distortion state of a structure for evaluation, and an equivalent non-proportional load factor f_{NP_eq} which is an average value of the variation of the value including the direction change of the main stress or the main distortion is calculated. An allowable life reduction ratio β_a is preset, and an equivalent non-proportional load factor f_{NP_a_eq} equivalent to the set allowable life reduction ratio β_a is calculated. When the equivalent non-proportional load factor f_{NP_eq} is smaller than the equivalent non-proportional load factor f_{NP_a_eq} equivalent to the allowable life reduction ratio β_a, the life evaluation is performed using equivalent stress or equivalent distortion, and when the equivalent non-proportional load factor f_{NP_eq} is equal to or more than the equivalent non-proportional load factor f_{NP_a_eq} equivalent to the allowable life reduction ratio β_a, the life evaluation in consideration of the load path is performed.;COPYRIGHT: (C)2012,JPO&INPIT