基于细观结构的2.5维机织复合材料强度预测模型

采用经纱矩形截面及纬纱六边形截面假设，将经纱的屈曲轨迹简化为折线形式，建立了2.5维机织复合材料单胞几何模型。以单胞为研究对象，引入改进的三维Hashin失效准则和Mises准则作为组分材料的失效判据，采用不同的刚度退化方式来表征不同的失效模式，建立了基于逐渐损伤理论的强度预测模型。利用有限元分析（FEA）技术，开发了相应的参数化2.5维机织复合材料逐渐损伤分析程序，预测了浅交弯联结构不同机织参数2.5维机织复合材料的拉伸强度，并模拟了经向拉伸和纬向拉伸的损伤扩展过程。与静拉伸试验结果相比，拉伸强度的预测误差在10%以内；模拟的失效模式与试验结果吻合较好。

Meso-structure of 2.5D woven composites and its strength prediction model

By adopting the hypothesis of rectangle section shape for warp, hexagon section shape for weft, and broken lines for the simplified orientation of warp, a unit-cell geometric model for 2.5D woven composites was developed. A progressive strength prediction model was developed based on the new model, which adopted Hashin and Mises failure criterions to identify failure of the yarns and matrix separately, and established different stiffness degradation method for different failure mode. A parametric progressive damage analysis program was developed by finite element analysis(FEA) software, which can predict the tensile strength, as well as the progressive damage behavior of bend-joint structure of 2.5D woven composite with different woven parameters, both in warp and weft directions. Compared with tensile experimental data, the strength errors are within 10% in both directions. The predicted failure modes agree well with the test results.