粒子群最適化法によるアルミニウム合金の塑性・クリープ疲労損傷則の同定

抄録

Automotive engine components made of aluminum alloys are often subjected to cyclic loading in a high-temperature range that exceeds 1/2 of the melting temperature Tm of aluminum alloys. The fatigue life of an aluminum alloy subjected to such loading should be evaluated by a fatigue damage law considering not only plastic damage but also creep damage. Then, in this study, we attempted to derive the fatigue damage law for an Al-Si-Cu-Ni-Mg alloy by conducting plastic-creep separation strain analyses using low cycle fatigue (LCF) test data. The material parameters used in the damage law were estimated by employing the particle swarm optimization (PSO) method. The derived fatigue damage law was applied to the fatigue life evaluation for the thermo-mechanical fatigue (TMF) tests which closely relate to the strength reliability evaluation for the engine components in actual use. The results show that the fatigue damage law with the material parameters estimated by the PSO method can well evaluate the fatigue life of the TMF test even though it was derived by using the LCF test data.