钨合金和钛合金绝热剪切破坏研究

介绍了中国科学技术大学在钨合金和钛合金的绝热剪切变形和破坏研究方面的工作．对截头圆锥形和预扭斜切圆柱形钨合金试件进行了分离式Hopkinson压杆试验，通过微观观察和数值模拟分析了试件中剪切失稳和绝热剪切带形成的机理，发现钨合金的细观结构和试件的应力状态对绝热剪切带形成的敏感性和位置有重要影响．通过钛合金板的冲塞实验研究了绝热剪切和动态破坏的联系，发现由于沿剪切带的孔洞形核和合并过程而出现断裂，最后导致冲塞，所有这些情况下，绝热剪切带在裂纹形成和扩展中起支配作用，正是绝热剪切带造成了试件的动态断裂．

Researches on Adiabatic Shear Failure of Tungsten Heavy Alloy and Ti6Al4V Alloy

An overview is given of the researches at USTC on adiabatic shear deformation and failure of tungsten heavy alloy and Ti6A14V alloy. SHPB tests of truncated-conic and pre-twisted inclined cylindrical tungsten heavy alloy (WHA) specimens are conducted. The mechanism of shear instability and adiabatic shear band (ASB) formation in the specimens is analyzed by microscopic observation and numerical simulation. It is found that the meso-structure of the tungsten heavy alloy and the stress state of the specimens have significant influences on the sensitivity and localization of ASB. The relationship between adiabatic shearing and dynamic failure is investigated by plugging experiment of Ti6 A14V alloy plates. It is found that fracture occurs by a process of void nucleation and coalescence within and along the shear band, leading to the final plug formation. In all these cases, the adiabatic shear band plays a dominant role in the formation and growth of cracks, and is responsible for the dynamic fracture of specimens.