中文摘要：

为研究复合材料夹层结构的疲劳性能,以轻木复合材料夹层结构为例,进行四点弯曲疲劳试验,得到结构的疲劳载荷-寿命（S-N）曲线;从疲劳损伤角度出发,描述结构的疲劳破坏机理;考虑剩余刚度,提出一种用于该类型结构的非线性疲劳损伤模型。结果表明：复合材料夹层结构的疲劳失效是一个损伤渐进累积的过程,位移演化呈现明显的三阶段特征;基于芯材剪切模量退化的指数型累积损伤模型可以较好地表达出复合材料夹层结构的损伤演化趋势。

英文摘要：

To study the fatigue properties of composite sandwich structures,the four-point bending fatigue tests of balsa wood core composite sandwich structures were carried out. The fatigue S-N curve of sandwich structures was obtained. The fatigue failure mechanism of composite sandwich structures was described from the viewpoint of fatigue damage. Considering the residual stiffness,a nonlinear fatigue cumulative damage model was proposed. The results show that fatigue failure of fiber reinforced composite structures is a slow stochastic damage accumulation process. The deflection evolution shows obvious three stage characteristics. The exponential cumulative damage model based on degradation of shear modulus of core material can well describe the damage evolution trend of the sandwich structures.