层间短纤维的Ⅱ型纤维桥联分析

对于层间加入增韧短纤维的连续纤维增强树脂层板的Ⅱ型层间增韧问题,考虑层间短纤维杂乱分布和几乎与层间裂纹平行的特点,基于基体剥落与纤维拉出耦合,考虑非桥联短纤维对剥离的干扰作用,建立了层间短纤维在Ⅱ型层间裂纹情况下的桥联模型.通过对不同角度桥联纤维拔出过程的分析,得到了桥联力与位移的关系.数值分析表明,除了角度接近90°的纤维外,拉出之前位移均很小,桥联力迅速增加,拉出过程中桥联力下降,位移大幅度增加,能量耗散主要发生在拉出阶段.随角度的增加,桥联力和能量耗散迅速减小.

Fiber Bridging Analysis of Interlaminar Short Fibers in Mode Ⅱ Delamination

To analyze the toughening mechanism of continuous fiber-reinforced resin composite laminates with interlaminar short fibers, the fact that the short fibers are distributed disorderly on interlayers and almost parallel to interlaminar cracks should be taken into consideration. Based on the coupling of matrix spalling and short fibers, the pull-out with the disturbance to unbridged short fibers during spalling considered, a bridging model is developed for interlaminar short fibers in mode II delamination to analyze the pull-out process of bridged fibers at different angles, the relationship between bridging force and crack-open displacement is obtained. The numerical results indicate that the displacement is very small except the angle is close to 90° and the bridging force increases rapidly before pull-out but decreases with greatly increasing displacement, i.e. the energy dissipation occurs mainly due to fibers' pull-out, and the bridging force and energy dissipation decrease with increasing pull-out angle.