单向层合板拉-拉及压-压疲劳加载材料退化模型

Material Degradation Models of Unidirectional Laminas Subjected to Tension-Tension or Compression-Compression Fatigue Loadings

以刚度退化为基础,并结合正则化疲劳寿命预测方法,推导建立了单层板疲劳累积损伤过程剩余刚度退化模型,同时给出了剩余强度退化模型。本文退化模型适用于拉-拉及压-压疲劳加载任意应力水平和应力比下的单层板疲劳寿命预测,所建立的剩余刚度退化模型显著减少为获得模型参数所必需的试验件数量,经济性好。最后,通过试验研究,建立了材料T300/BMP-316单向层合板疲劳加载各主方向剩余刚度退化表达式、剩余强度退化表达式及疲劳寿命表达式,为层合板结构疲劳损伤分析提供了有力依据。

The residual stiffness degradation model based on the degradation of stiffness of the composite lamina subjected to tension-tension or compression-compression fatigue loadings is deduced and established by coupling the normalized fatigue life method, and the residual strength degradation model also given, which is applied to predict the fatigue life of a unidirectional ply under arbitrary state of stress and stress ratio. The amount of specimens used to acquire parameters in models is reduced, which is high effective. The experimental research for mechanical behavior of a unidirectional lamina is to set up expressions of the normalized fatigue life, the residual stiffness degradation and the residual strength degradation of a unidirectional ply in the longitudinal, transverse and in-plane-shear directions, which provides stable foundament for analyzing fatigue behavior of composite structures.