考虑初始损伤的脆性疲劳损伤模型及验证

Brittle fatigue damage model including initial damage and model verification

疲劳损伤导致的破坏是工程结构最常见的失效形式之一。利用不可逆热力学理论框架和损伤的微观力学,基于脆性损伤的机理,建立了一种新的脆性疲劳损伤模型。新模型推导严密,以应力幅和材料损伤参数为控制变量,考虑了材料的初始损伤,并以12Cr1Mo V钢为例进行实验验证。结果表明:新模型包含了初始损伤变量,可以用来估算材料的初始损伤;新模型在疲劳过程的初期,损伤很小时,相比同类型疲劳损伤模型具有显著优势,同时新模型能够应用于脆性材料疲劳损伤的寿命预测;新模型比同类型疲劳损伤模型形式简单、参数少,且与实验结果符合的更好。

Failure caused by fatigue damage is one of the most common failure modes of engineering structures. By using irreversible thermodynamics and microscopic damage mechanics,a new model of brittle fatigue damage based on brittle damage mechanism was proposed. A strict and detailed derivation of the new model including initial damage by using the stress amplitude and the characteristic parameters of damaged material as the dominating variables was given. An experiment on 12 Cr1 Mo V steel was performed as an example.It is shown that the new model including the initial damage variable can be used to estimate the initial damage of the materials; the new model has significant advantages compared with similar fatigue damage models at the beginning of the fatigue process when the damage is very small,and meanwhile the new model can be applied in life prediction of the brittle material fatigue damage; the new model is simple,has small amount of parameters,and is in better agreement with the experimental results than similar models of fatigue damage.