超高分子量聚乙烯无纬布准静态材料力学性能研究

A STUDY OF THE MECHANICAL PROPERTIES OF CROSS-PLIED UNIDIRECTIONAL UHMWPE SHEETS UNDER QUASI-STATIC LOADING

超高分子量聚乙烯(UHMWPE)无纬布是制作软质防弹衣的主要材料。首先通过实验研究了UHMWPE无纬布在准静态载荷下的拉伸、面内剪切和冲压式剪切特性。实验表明,UHMWPE无纬布在准静态拉伸过程中发生突然的脆性断裂,拉伸强度约为641MPa;面内剪切实验中试件的力-位移曲线呈现明显的非线性,材料在受力方向发生了塑性强化,试件的主要失效形式为基体的剪切破坏,失效后纤维夹角从90°减小到74°;设计制造了一套用于测量UHMWPE无纬布沿厚度方向剪切强度的夹具,实验得到该型无纬布的剪切强度约为168MPa。随后采用壳单元建立对应的有限元模型,对拉伸实验和冲压式剪切实验过程进行数值模拟。拉伸数值结果在最大拉力、拉伸强度和失效应变等指标上与实验结果较一致,并给出了拉伸过程中试件中的应力分布情况;冲压式剪切数值结果给出了剪切失效部位每层单元的应力变化情况。

Cross-plied unidirectional Ultra-high molecular weight polyethylene （UHMWPE） sheets is the main material for the production of soft body armor. At first, the tensile behavior, in-plane shear behavior and punch- shear behavior of UHMWPE sheets under quasi-static loading were studied using experimental method. The experi- mental show a sudden brittle fracture occurred in the quasi-static tension process, the tensile strength is about 641MPa. A highly non-linear behavior of force-displacement curve was observed during in-plane shear process, plastic hardening occurred in the direction of the tension force and matrix shear failure is the main failure mode. Af- ter failure, the angel between fibers in adjacent plies has reduced from 90~ to 74~. The through-thickness shear strength is about 168MPa, which was obtained using a set of special clamp. Then shell elements were adopted to es- tablish the finite element model for studying the tensile experiment and punch-shear experiment process numerically. The numerical results are in good agreement with the tensile experiment results in maximum tensile force, tensile strength and failure strain, and the stress contours in the UHMWPE sheets were also obtained; The stress history of elements in the shear failure area were captured using numerical method.