采用激光速度干涉技术,连续测量了AD95氧化铝陶瓷在一维应变冲击压缩下的自由面速度剖面,通过对速度剖面特征的分析,讨论了AD95陶瓷等脆性材料在冲击压缩下是否存在破坏波现象及其与材料特性的关系。研究结果表明:冲击加载应力在4.4-7.3GPa范围,即从小于到略大于雨贡纽弹性极限(约5.5GPa),在AD95陶瓷的自由面速度剖面中都未出现表征破坏波现象的二次加载信号,表明未发生破坏波形式的严重压缩损伤;但是,自由面速度剖面中特征点的规律性时序关系和前沿弥散特征都表明,在所讨论的加载应力范围内,AD95陶瓷材料发生了一定程度的压缩损伤;断裂韧性是影响材料在冲击压缩下是否发生破坏波现象的重要因素,断裂韧性较低,冲击波加载下易于形成大量微裂纹扩展和贯通,使材料发生"粉碎性"的严重破坏,是产生破坏波现象的重要条件之一。
The free surface velocity profile of AD95 ceramic target was measured through laser interfer- ometry under one-dimensional plane strain shock compression. Whether failure wave happened and its relationship with material property were discussed by the analysis of velocity profile characteristic. In an impact stress range from 4.4 to 7.3 GPa (aHZL is about 5.5 GPa), the free surface velocity profile has no appearance of reload signal ,which means that there is no appearance of seriously damaged and fragmentized interface as that observed in glass and rock,like a failure wave. The analysis about the free surface velocity profile indicates that the calculated characterizing time difference is regularly less than the experimental value,and the rising foreland has a dispersive property even though the loading stress is less than ФHEL. These findings demonstrate that, to some extent, AD95 ceramics might have produced a certain weak compressive damage at the low-stress region. The fracture toughness is a sig- nificant ingredient that affects the failure wave phenomena. Materials with relatively lower fracture toughness are prone to form microcracks extension,connection and finally lead to the serious breakage and shatter into pieces,which means the appearance of failure wave.