混合加载条件下的复合材料界面裂纹分布特性

Distribution characteristics of interface cracks in composite materials under mixed-mode loading

  • 摘要: 当前,针对非单轴加载条件下的界面脱粘行为,现有理论模型的预测精度仍显不足,其根本原因在于建模过程中缺少了一类关键信息,即界面裂纹的分布特性。因此,获取清晰、全面的界面裂纹观测数据成为解决这一问题的关键。鉴于此,本文选取偏轴拉伸作为非单轴加载的典型代表,以斜十字形试件作为研究对象,利用Micro-CT技术对界面结构进行三维图像表征。针对经过拉伸主导与剪切主导的非单轴加载作用后的试件,测量其中纤维表面脱粘区域的面积占比,并分析该占比沿纤维轴向和周向的变化规律。实验结果表明,非单轴加载作用下界面裂纹的分布特性主要受载荷水平、加载模式以及相邻纤维方位的影响;对拉伸-剪切应力比例进行细微调整,可能会显著改变界面裂纹分布的均匀性与随机性。

     

    Abstract: Current theoretical models exhibit limited predictive accuracy in describing interface debonding behavior under non-uniaxial loading conditions, primarily due to the omission of critical modeling parameters such as the characteristics of interface crack distribution. Consequently, obtaining comprehensive and detailed observation data of interface crack has become pivotal for addressing this challenge. This study employs off-axis tensile testing as a representative non-uniaxial loading scenario, using oblique cross-shaped specimens as research objects. Three dimensional image characterization of interfacial structures was conducted using Micro-CT technology. For specimens subjected to tensile-dominated or shear-dominated loading conditions, the area ratio of debonding zones on fiber surfaces was measured, with analysis focusing on axial and circumferential variation patterns. Experimental results demonstrate that the interface crack distribution under non-uniaxial loading is predominantly influenced by the load magnitude, loading mode, and fiber orientation. Subtle adjustments to the tensile-to-shear stress ratios may significantly alter the uniformity and randomness of the crack propagation patterns.

     

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