纤维增强复合材料层合板破坏机理的数值分析与研究

Despite the fact that extensive work has been done on the numerical simulation of damage in fiber-reinforced composite materials with their wide applications, the failure mechanisms have not yet been fully understood because of the complicated stress states at the notch tip of composite laminates. The main purpose of this project is to determine the failure mechanisms of centre notched composite laminates by modeling the stress states at notch tip accurately. To achieve this goal, an efficient and robust computational tool is developed to perform progressive failure analysis on laminates loaded in tension, shear or combined loading. To accurately capture the stress concentration at the notch tip, in-ply cohesive layers along fiber direction will be introduced in the finite element model to simulate the splitting. Meanwhile, to alleviate the element size effect, in-ply cohesive layers perpendicular to the fiber direction will also be introduced to model the fiber breakage and microbuckling, which are the dominant failure modes in tension and shear, respectively. Failure modes and failure loads obtained from finite element analyses will be compared with experimental results to confirm the failure mechanisms of composite laminates. This project will provide fundamental theories on the composite structure design, performance and life prediction.

随着纤维增强复合材料的广泛应用，科研工作者们在纤维增强复合材料破坏的数值模拟方面做了大量的研究工作。但不同于一般均匀各向异性体，由于复合材料层合板内缺陷边缘的应力复杂性，复合材料的破坏机理还没有被完全理解。本项目将建立一个有效的有限元模型来模拟含中心裂纹的复合材料层合板在拉伸、剪切和拉剪混合载荷下的破坏行为，旨在通过准确描述裂尖应力场来明确复合材料层合板的破坏机理。为了准确模拟裂纹尖端的应力集中，模型中将引入层内平行于纤维方向的cohesive单元来模拟劈裂；为了消除有限单元大小的影响，模型中将引入层内垂直于纤维方向的cohesive层来模拟纤维断裂和微屈曲（microbuckling）。最终数值模拟所得到的破坏形式和破坏载荷将与实验结果进行对比验证。本项目研究可以为复合材料结构设计、可靠性分析和寿命预测提供依据。

先进纤维增强复合材料具有高比模量和高比强度等优点,因此在航空航天、兵器、船舶等领域得到日益广泛的应用。本项目通过实验和有限元方法对纤维增强复合材料进行了破坏分析, 建立了有效的有限元模型来模拟含中心裂纹的复合材料层合板的破坏行为，通过准确描述裂尖应力场进一步理解了复合材料层合板的破坏机理。为了准确模拟裂纹尖端的应力集中，有限元模型中引入了层内平行于纤维方向的cohesive单元来模拟劈裂；为了消除有限单元大小的影响，模型中引入了0o层内垂直于纤维方向的cohesive层来模拟纤维断裂和微屈曲。最终数值模拟所得到的破坏形式和破坏载荷与实验结果进行了对比验证。