一种基于复合材料剩余强度的衍生疲劳损伤模型

A derivative fatigue damage model based on residual strength of composites

为了研究纤维增强树脂复合材料在疲劳载荷作用下的损伤发展规律,提出了一种基于复合材料剩余强度的归一化衍生疲劳损伤模型。在该模型中,假定累积损伤与应力水平呈线性关系,可以由拉-拉疲劳试验的应力水平的损伤曲线衍生出未试验的应力水平的损伤曲线。对直径为8 mm的碳纤维增强树脂复合材料(CFRP)索材进行了不同应力幅的疲劳试验,并同时采用了文献中玻璃纤维增强树脂复合材料(GFRP)层合板的试验数据验证模型的可靠性,试验结果表明:损伤模型能较好地反映出三阶段的发展规律,衍生的损伤曲线与试验数据拟合出来的损伤曲线偏离度较小。此外,本文还研究了应力水平对复合材料损伤演化的影响,结果表明随着应力水平的增大,损伤曲线相邻阶段的边界变得不明显。

In order to investigate the damage development regularity of composites subjected to fatigue loading, a normalized derivative damage model based on the residual strength was proposed. In this model, it is assumed that the cumulative damage and stress level have a linear relationship, based on which, the damage curves of untested stress levels can be derived from that of tested stress levels with positive stress ratios. Fatigue tests of 8 mm-diameter carbon fiber reinforced polymer(CFRP) composite tendons for different stress situations were conducted, and the experimental data of glass fiber reinforced polymer(GFRP) composite laminates from references were adopted to validate the reliability of the proposed damage model. The experimental results show that the damage model can well reflect the three-stage development law of CFRP composite tendons, and the derived damage curves show a good agreement with the damage curves obtained by fitting the experimental data. Besides, this paper investigates the influence of stress level on the damage evolution of composites. As the stress level increases, the boundaries between adjacent stages of damage curves become unobvious.