平板冲击下氧化铝陶瓷弹性前驱波衰减的细观机理  

Mesomechanism of elastic precursor decay in alumina under plate impact loading

作　　者：冯晓伟[1] 李俊承[1] 王洪波[1] 常敬臻[1] 

机构地区：[1]中国工程物理研究院总体工程研究所,绵阳621900

出　　处：《物理学报》2016年第16期178-187,共10页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11502258;11272300);中国工程物理研究院科学技术发展基金(批准号:2014B0101009)资助的课题~~

摘　　要：利用一级轻气炮开展了不同厚度氧化铝陶瓷样品的平板冲击压缩实验,并借助激光速度干涉仪(VISAR)测试了样品的自由面速度历程.根据自由面速度历程确定了不同厚度氧化铝陶瓷样品的Hugoniot弹性极限值,结果显示,冲击压缩下氧化铝陶瓷中存在弹性前驱波衰减现象.进一步基于氧化铝陶瓷的细观结构扫描电镜(HEL)图像,分析了氧化铝陶瓷的细观结构特征,构建了含晶相、玻璃相等细观特征的力学模型.数值模拟冲击压缩加载下氧化铝陶瓷细观结构的力学响应过程,从细观层次上分析了弹性前驱波衰减现象的产生机理,指出冲击压力低于HEL时材料的细观损伤引起的能量耗散以及前驱波在细观结构晶界处反射和透射引起的能量分散过程是其产生的主要原因.The Hugoniot elastic limit （HEL） of ceramics is explained as the limit of elastic response and the onset of failure under dynamic uniaxial strain loading, which is an important parameter for understanding the dynamic properties of ceramic materials. Previous experimental impact studies showed an interesting phenomenon that the HEL decreases with the increase of sample thickness, which is termed the elastic precursor decay. This phenomenon has not been explained by a suitable mechanism to date. Recently it has become apparent that mechanical response of polycrystalline ceramics is governed by mechanism operating at a grain level. So the objective of the present work is to develop a mechanism that can illustrate this phenomenon on a mesoscale. In this paper, the plate impact experiments of alumina with varying thickness values are conducted by using one-stage light gas gun. The histories of the rear free surface velocity of the samples are recorded by a Velocity Interferometer System for Any Reflector （VISAR）. The HELs of alumina samples with different thickness values are obtained from turning point of elastic phase to inelastic phase in the temporal curves of free surface velocity. It is confirmed that the HEL of alumina decreases with increasing the sample thickness obviously, namely elastic precursor decay phenomenon. It is considered that this phenomenon is related to the failure mechanism of shocked alumina at a grain level. Thus, the mesoscopic model of alumina, including alumina grain phase and glass binder phase, is developed according to the microstructure properties of tested sample observed experimentally. Mesoscale simulations are presented to study the mesoscale failure properties of alumina at various impact velocities. The results show that inelastic responses, such as microcracking, grain plasticity, are observed in microstructure of alumina even when the peak-shock stress is less than the magnitude of HEL. As is well known, the evolution process of cracking or plasticity is the energy diss

关 键 词：冲击压缩 氧化铝陶瓷 弹性前驱波衰减 细观力学响应 

分 类 号：O343[理学—固体力学]