Modeling the Response of 3D Textile Composites under Compressive Loads to Predict Compressive Strength

The compression response of 3D woven textile composites (3DWC) that consist of glass fiber tows and a polymer matrix material is studied using a combination of experiments and finite element based analyses. A previous study reported by the authors consisted of an experimental investigation of 3DWC under high strain rate loading, Pankow, Salvi, Waas, Yen, and Ghiorse (2011). Those experimental results were explained by using the finite element method to analyze the high rate deformation response of representative volume elements (RVEs) of the 3DWC, Pankow, Waas, Yen, and Ghiorse (2012). In this paper, the same modeling strategy is used to examine the quasi-static, compressive deformation response of 3DWC. The effect of using different numbers of the textile repeat unit architecture in the RVE, on the predicted compression strength, is examined. The transitions in failure modes that are seen in experiments are seen to be captured by the model that is presented here.     

Modeling the response,strength and degradation of 3D woven composites subjected to high rate loading

Experimental results which were obtained using a split Hopkinson pressure bar (SHPB) apparatus to determine rate dependent effects, and reported by the authors in [1] are used as the basis to perform dynamic simulations of 3D woven composites (3DWCs) using representative unit cells (RUCs). The input material properties for the RUC simulations were determined from the concentric cylinder model (CCM) in conjunction with the geometry of the textile architecture, mechanical properties of pure epoxy samples and fiber mechanical properties. The RUC model incorporates rate dependent plasticity. Additionally, linear-eigen perturbations that correspond to buckling modes are used to seed imperfections in the RUC model to capture buckling and subsequent failure that was observed in experiments. The RUC model results showed good agreement with experiment and correctly captured the observed modes of failure while pointing to transitions in failure modes.     

不规则孔隙对复合材料横向拉伸力学性能的影响

本文主要研究分析了不规则形状孔隙对复合材料单向板横向拉伸力学性能的影响。首先通过C++编写不规则孔隙随机分布算法。然后通过Python参数化生成包含随机分布纤维和不规则孔隙的重复胞元（Repeating unit cell,RUC）。最后使用有限单元法（Finite element method）分析研究了不规则孔隙对单向板横向拉伸性能（横向弹性模量和横向拉伸强度）的影响。研究结果显示,孔隙的形状会影响单向板的初始损伤、损伤扩展和最终破坏。随着孔隙率的增大,横向弹性模量和横向拉伸强度都减小。相对于横向弹性模量,孔隙率对横向拉伸强度的影响较大。