有限变形下一种橡胶多轴疲劳损伤参量的计算

A Method to Calculate a Multiaxial Fatigue Damage Parameter for Rubber Materials Under Finite Deformation

橡胶材料因其良好的弹性、可塑性等特点广泛应用于汽车工业中,橡胶部件的疲劳破坏是常见的重要问题之一。橡胶部件实际服役工况多为多轴疲劳载荷,研究橡胶材料多轴疲劳寿命的预测方法很有必要。开裂能密度(Cracking energy density,CED)参量不仅能表征疲劳损伤,还具有预测破坏方位面的特点。基于CED的定义式推导该参量适用于有限变形的一般表达式,并得出了当采用Ogden和Mooney-Rivlin超弹性本构模型时计算该损伤参量的有效方法。为了验证该计算方法的正确性,基于单轴和多轴疲劳试验数据,对比了CED和其他损伤参量与橡胶疲劳寿命的相关性。结果表明:相比应变能密度(Strain energy density,SED)和最大主伸长率,CED能更好地将单轴疲劳寿命和多轴疲劳寿命统一起来。

Rubbers are widely used in automotive industry due to their superior elasticity and plasticity. Rubber components,however,are frequently subjected to multiaxial cyclic loading in service,which makes them prone to fatigue failures.Therefore,availability of an effective technique to predict fatigue life under actual complex loading is very valuable to the design procedure. Cracking Energy Density（CED）,which is a plane-specific fatigue damage parameter for dealing with rubber multiaxial fatigue issues,is re-derived assuming that rubber materials are under a state of finite deformation. The yielded formula of CED is appropriate for commonly used hyperelastic constitutive models. To validate the CED calculated from the presented method,the measured fatigue lives under fatigue loadings of uniaxial tension and equiaxial tension are also used to investigate the correlations of CED and other damage parameters. It is shown that the CED is a more appropriate damage parameter for multiaxial fatigue life prediction compared to the maximum principal stretch and SED,which is commonly used for rubber uniaxial fatigue prediction.