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对界面含短纤维的复合材料夹芯梁增韧特性进行了实验和数值研究。采用真空辅助树脂注射工艺制成复合材料夹芯梁,并测定了含增强与未增强复合材料夹芯梁的界面断裂韧性。基于单根短纤维在界面裂纹扩展时其剥离和拔出过程产生的能量耗散,建立了相应的细观模型。然后,假设短纤维在界面内随机均匀分布,得到在单位面积下短纤维能量耗散的宏观表达式。在宏观尺度上,建立了用于界面裂纹扩展分析的双悬臂梁有限元模型,通过引入非线性弹簧单元,以反映界面短纤维所产生的桥联特征,并采用虚裂纹闭合技术计算了裂纹尖端的能量释放率。通过典型复合材料夹芯梁断裂分析和参数讨论,证实了本文中提出的随机分布细观模型预测短纤维耗散能量的有效性。实验及数值结果表明,在复合材料夹芯结构界面中引入短纤维将是一种提高其界面断裂韧性的有效措施。
The toughening properties of the sandwich composite beam with interfacial short fibers were studied experimentally and numerically. The vacuum assisted resin injection process was used to fabricate the composite sandwich beam and the interfacial fracture toughness of the sandwich beam with or without reinforced composite was measured. Based on the dissipated energy of single short fiber during the process of interface crack propagation, the corresponding mesoscopic model was established. Then, assuming that the short fibers are randomly and uniformly distributed in the interface, a macroscopic expression of the energy dissipation of short fibers per unit area is obtained. On the macroscopic scale, a finite element model of double cantilever beam was established for the analysis of interface crack propagation. By introducing nonlinear spring elements to reflect the bridging characteristics of the interface short fibers, the crack tip was calculated by the virtual crack closure technique The energy release rate. The fracture analysis and parameter discussion of the typical composite sandwich beam show that the proposed random distribution model can predict the energy dissipation efficiency of short fibers. The experimental and numerical results show that the introduction of short fibers in the interface of the composite sandwich structure will be an effective measure to improve the interface fracture toughness.