W-Ni-Fe合金静动态力学性能及数值模拟研究

采用MTS材料实验机和旋转盘式间接杆-杆型冲击拉伸试验装置对质量百分数为91%的钨合金材料力学性能进行了研究.基于试验结果,建立了具有钨合金典型细观结构的单胞有限元模型,采用不动点迭代方法给出了该有限元模型的真实位移条件,分析了不同颗粒度形状以及钨颗粒体积含量等细观参量对钨合金材料在不同载荷作用下力学性能的影响,给出了钨合金材料在不同载荷作用下的应力-应变曲线,并与试验结果进行了对比,二者具有较好的一致性.通过数值模拟发现不同颗粒度的钨合金材料均为应变率敏感材料;钨颗粒长径比对材料力学性能的影响不大;随着钨颗粒质量分数的增加,钨合金材料的屈服应力有所提高.

MECHANICAL PROPERTY AND NUMERICAL SIMULATION ON W-NI-FE ALLOYS

Tungsten alloy is a type of particulate reinforced composites and has wide military and civilian applications. It can be used as kinetic energy penetrator, radiation shielding material, balance mass in aerospace, vibrating material in cell phones, etc. These alloys are characterized by the high strength, high density and high toughness resulting from their special microstructural features. Because of their good strength as well as ductility, these alloys have been extensively studied for a variety of promising applications. So far, most studies mainly focused on the understanding of their densification mechanism, the two-phase microstructure evolution mechanism during sintering, and the relationship between the microstructure and mechanical properties. The two-phase composite structure of tungsten alloy determines that the macroscopic deformation and fracture behavior have close relation with the microstructure of the composites. Therefore, it is important to investigate the relationship between the microstructure and the mechanical properties of the composites under different loadings, which provides practical values for the improvement of the mechanical properties and the optimization of tungsten alloys. In the current paper, MTS and SHPB techniques are used to investigate the mechanical properties of 91wt.% tungsten alloys. Based on the experimental results, finite element models of unit cells with typical structures of tungsten alloys are established. Fixed point iteration method is adopted to provide real displacement conditions for the finite element models. The effects of the microstructure parameters, such as particle size and volume fraction, on the mechanical characteristics of tungsten alloys under different tensile loadings, are examined and the corresponding stress-strain relations are obtained. The comparison of numerical predictions and the experimental results shows a good agreement. The numerical simulations demonstrate that tungsten alloys are rate-independent materials. The aspect ratios of tungsten particle have no obvious influence on the mechanical behavior of tungsten alloys, and the yield stress increase with the mass fraction of tungsten particles.