复合材料层板损伤后刚度衰退的实验研究

Experiment Study of Stiffness Degradation for Damaged Composite Laminates

对复合材料单向板进行了0°、90°、45°拉伸实验,对铺层为[0°/90°]、[±45°]的层合板进行了拉伸实验,对玻璃纤维、碳纤维、芳纶纤维缠绕的NOL环试样分别进行了短梁剪切实验。实验结果表明:碳纤维/环氧树脂基体复合材料单向板没有明显的非线性行为,而层合板在树脂开裂、面内及层间剪切破坏导致的刚度降低却很明显。层间剪切破坏不仅导致剪切刚度的降低,还会引起弯曲刚度的降低。玻璃纤维、芳纶纤维增强树脂基复合材料在三点弯曲实验过程中体现了较强的抗损伤能力,韧性较好;而碳纤维增强树脂基复合材料抗层间损伤能力较差。本文用标准实验方法,跟踪载荷-变形曲线,得到了用于应力分析的刚度衰减系数。用最大应力准则及实验得到的刚度衰减系数,对直径为1400mm的纤维缠绕壳体进行了变形分析,计算结果与实验值一致性较好。

Tension tests were performed for unidirectional laminas under 0°, 90 °, 45 °direction, and for (\), \ laminates. Short-beam shear tests were carried out for NOL hoop specimens reinforced by glass fiber, carbon fiber and Kevlar fiber respectively. The results showed that there were not obvious nonlinear behaviors for the unidirectional brittle matrix composite, but stiffness degradation due to matrix cracks or delamination of laminates were obvious. The delamination can not only induce shear stiffness degradation, but also bending stiffness degradation. The specimens reinforced by glass fiber and Kevlar fiber have better damage resistance than those reinforced by carbon fiber. The stiffness degradation factor can derived from the load-displacement curve by standard test methods. Deformation analysis for 1400mm in diameter filament wound case was completed with the maximum stress criterion and the stiffness degradation factor obtained from tests. The calculated results and experiment data matched well each other.