基于强度变化特性的随机谱载荷下疲劳寿命预估模型

摘要

提出了一种新的随机谱载荷下构件的疲劳寿命评估模型.该模型以结构强度变化特性为基础,考虑低幅载荷强化和损伤的双重效应,既有清晰的物理意义,又更合理地反映了疲劳过程中零件强度值随着载荷的变化而相应地增高和衰减的特性,克服了传统疲劳累积损伤模型忽略低幅载荷强化作用的缺陷.经过两种构件的试验验证表明,此模型与传统的累积损伤模型相比能更准确地预测构件在随机载荷下的寿命,为结构的轻量化设计提供理论与技术依据.%A new fatigue life prediction model for parts and components under random spectrum loading is put forward. Based on the features of strength variation with consideration on the dual effects of strengthening and damaging of low-amplitude loads, the model not only has clearer physical meaning but also rationally reflects the feature that the fatigue strength of part's rises and lowers with the changes of random loading, overcoming the deficiency of traditional fatigue damage accumulation model in ignoring the strengthening effect of low-amplitude loading. The results of verification by the tests on two example components indicate that the new model can more accurately predict the fatigue life under random loading than traditional model, providing a theoretical and technical base for the lightweighting design of structures.