缺胶缺陷对复合材料L型层合板侧弯承载行为的影响

Impact of resin-missing defects on the bending behavior of L-shaped laminates

  • 摘要: 本文结合实验与数值分析方法,探讨了缺胶缺陷对L型复合材料层合板侧弯承载能力及失效过程的影响。实验方面,通过在纤维层局部涂抹脱模蜡,采用真空辅助树脂灌注工艺制备了含缺胶缺陷的L型层合板,开展侧弯试验分析了缺胶缺陷位置的影响规律。数值分析方面,构建了含缺胶缺陷L型层合板三维有限元模型,基于Hashin失效准则与内聚力方法分析层内与层间失效,探究缺胶缺陷对失效行为的影响机制。实验结果表明,缺胶缺陷会显著降低L型层合板的承载能力,并改变其损伤扩展路径,由无缺陷层合板中间区域的主裂纹扩展转变为缺胶缺陷区域的多层分散扩展。数值模拟揭示了缺胶区域的应力集中是导致缺胶区提前失效的主要原因。且缺胶缺陷的局部损伤改变了周边应力的重分布形式,剩余部分多个分层同步扩展。缺陷位置对承载力有显著影响,中间层影响最大,内表层次之,外表层最小。本研究可为含缺胶缺陷L型层合板的损伤行为研究、安全性评估及损伤容限设计提供参考。

     

    Abstract: In this paper, both experimental and numerical analysis methods were combined to investigate the effects of resin-missing defects on the flexural bearing capacity and failure process of L-shaped composite laminates. In experiment, resin-missing defects were introduced by spread release wax on the fiber reinforcement and L-shaped laminates was fabricated by vacuum-assisted resin infusion molding process. Bending tests were conducted to analyze the influence of resin-missing defects. In numerical analysis, a three-dimensional finite element model of the L-shaped laminates within resin-missing defects was developed, where Hashin failure criterion and cohesive zone method were used to simulate the intra- and inter-laminar failure. The influence mechanism of resin-missing defects on laminate failure behavior were explored. The experimental results demonstrate that resin-missing defects significantly reduce the bearing capacity of L-shaped laminates and alter the damage propagation paths. Specifically, the damage mode shifts from a main crack propagation in the mid-region of defect-free laminates to a multi-layer dispersed propagation in the defected ones. The numerical simulations reveal that stress concentration caused by the resin-missing defects triggers the premature failure. The local damage subsequently changes the redistribution of local stresses, leading to multi-delamination in surrounding layers. The location of resin-missing defect plays a significant role on the influence of bearing capacity. The middle layer location has greatest influence, followed by inner location, while outer layer defect shows the least impact. This study provides valuable insights into the damage behavior, safety assessment, and damage tolerance design of L-shaped laminates within resin-missing defects.

     

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