冲击载荷作用下钨合金材料绝热剪切带形成机理

对钨合金材料在受冲击载荷作用下绝热剪切带形成机理进行了研究，重点考察了受力条件的影响，用分离式Ｈｏｐｋｉｎｓｏｎ压杆装置对阶梯圆柱形、哑铃形和直圆柱形钨合金试件进行了冲击加载，利用光学显微镜对冲击后的试件进行了显微组织观察。用ＡＢＡＱＵＳ大型数值分析软件对试件进行有限元分析，材料模型采用热粘塑性形式的Ｊｏｈｓｎｏｎ－Ｃｏｏｋ模型，实验和数值计算结果表明：受力条件对钨合金材料的变形、损伤（微型纹和绝

FORMATION MECHENISM OF ADIABATIC SHEAR BAND IN TUNGSTEN HEAVY ALLOYS

Dynamic deformation and failure behavior of a tungsten heavy alloy under complex stress condition were studied. A testing geometry, such as dumbbell and step shape specimens, generating controlled stress state was used in an attempt to induce strain localization in tungsten heavy alloys. Dynamic load was applied to specimens with its axis parallel to the loading axis by use of a split Hopkinson pressure bar (SHPB) apparatus which generates a strain rate as high as 103 s-1. The microstructure was examined by optical microscopy, revealing that strain localization in the form of intense shear bands initiated at geometrical stress concentration sites in the all dynamic compression samples. Two of the major conclusions can be drawn from this investigation, first, dynamic deformation and failure modes are significantly dependent on the geometry of specimens generating controlled stress state, and second, localization is a propagation phenomenon, starting at geometrical (stress concentration) sites and propagating as a thin band.