二步法三维编织复合材料弹性性能的有限元法预报

用有限元法预测了二步法三维编织复合材料的有效弹性性能。在二步法方型三维编织复合材料细观结构大单胞模型的基础上, 考虑复合材料中纤维束的连续性及其空间的交织效应, 用离散杆单元构成的桁架结构有限元模型等效代替复合材料承受单轴拉伸载荷时的受力响应。同时, 以轴向拉伸性能测试试样为对象, 应用有限元软件包MARC 的结构静力分析部分计算了轴向弹性模量和泊松比, 数值计算结果与实验结果一致性较好。参数分析结果表明, 轴向弹性模量随轴纱与编织纱线密度之比和节距长度的增加呈增加趋势。

FINITE ELEMENT PREDICTION OF ELASTIC PROPERTIES OF TWO-STEP THREEDIMENSIONAL BRAIDED COMPOSITES

On the basis of the large unit cell of two-step rectangular three-dimensional braided composites, the finite element model of a spatial truss consisting of beam elements is developed to model the effective mechanical properties of the composites under the uniaxial tension. Yarns and resin are treated as beam elements. The finite element method can be employed for predicting the mechanical properties of the composites. The uniaxial tensile tests of samples are simulated utilizing the software MARC. Results of the effective elastic properties and Poisson ratios predicted by this approach compare favorably with the experiment data. Parametric studies show that the axial elastic modulus of the composites increases with increasing the linear density ratio of axial yarn to braider yarns and pitch length.