二维三轴编织复合材料压缩失效行为的细观有限元模拟

为研究典型二维三轴编织复合材料（2DTBC）的压缩破坏机理，建立了细观有限元模拟方法体系。提出了反映编织复合材料真实几何特性的单胞模型建模策略，根据Murakami-Ohno损伤理论建立了各向异性损伤模型来模拟纤维束中的损伤起始和扩展行为，通过引入波动系数描述了纤维束的起伏状态，并采用内聚力单元来模拟界面分层。在此基础上，分析得到了二维三轴编织复合材料在压缩载荷下的破坏过程，研究了压缩载荷下纤维束和界面层的损伤演化，探讨了纤维束波动对压缩性能的影响规律。通过与相关试验结果对比，该模型能够准确预测二维三轴编织复合材料在面内压缩载荷下的力学响应和主要失效行为，以及自由边效应。细观失效过程分析结果表明，二维三轴编织复合材料轴向压缩的破坏是由轴向纤维束的纤维压缩失效主导的；横向压缩破坏则是由偏轴纤维束的纤维压缩失效引起的。

Meso-scale finite element simulation of compressive failure behavior of two-dimensional triaxially braided composite

A meso-scale finite element model is developed to predict the progressive damage behavior of the two-Dimensional Triaxially Braided Composite (2DTBC) subjected to compressive loading conditions. A unit cell model that reflects the realistic geometrical properties of the braided composite is established. Based on Murakami-Ohno damage theory, an anisotropic damage model is established to simulate the damage initiation and the propagation process in fiber bundles. Undulation coefficient is introduced to describe the extent of undulation. The interfaces are simulated using the cohesive element model. The compressive damage process of 2DTBC is systematically illustrated and analyzed using the meso-scale finite element model, with special focus on the damage evolution process of fiber bundles and interfaces, and the effect of fiber bundle undulation on the effective compressive properties. The proposed model shows excellent correlation with the experimental results, not only capturing the global stress-strain responses, but also capturing the progressive damage behavior and the free-edge effect of the composite. The results indicate that the axial compression failure of the 2DTBC is dominated by the fiber-compression failure of axial fiber bundles, and the transverse compression failure is caused by the fiber-compression failure of bias fiber bundles.