氧化铝陶瓷压缩破坏过程离散元数值模拟

Discrete Element Simulations on Compressive Fragmentation of Alumina Ceramics

陶瓷的压缩破坏是一个爆炸式破碎的过程,在短时间内急剧释放大量能量,并伴随大量高速飞行碎片的产生,实验上较难获取陶瓷压缩破坏过程中碎片的飞溅速度。本文采用离散元数值模拟氧化铝陶瓷的压缩破碎过程,分析了不同应变率下产生碎片的尺寸分布、碎片的平均飞溅速度,以及试件内部不同区域碎片的速度变化规律。研究表明:(1)陶瓷的表观破坏强度以及破碎后碎片的平均飞溅速度与加载应变率正相关;(2)碎片飞溅速度与其初始位置相关,外侧碎片的飞散速度最大,随着初始位置与试件中心轴距离的减小,碎片飞溅速度逐渐减小;(3)随着加载应变率的提高,碎裂产生的碎片数逐渐增多,对应的碎片平均尺寸变小。进一步讨论了试件压缩破碎过程中的能量守恒和转换模式,并对碎片飞溅的平均速度进行了理论分析。

The compressive failure of ceramics is always accompanied by an explosive fragmentation process that creates lots of fragments flying away at high speed.Due to experimental limitations,the details of compressive fragmentation occurred inside the specimen are not clear.In this paper,the compression crushing process of alumina ceramics was numerically reproduced by discrete element method.The size distribution of fragments under different strain rates,the average splash velocity of fragments and the variation law of fragment velocity in different areas within the specimen were analyzed.The simulation results show that as follow:(1)Both the compressive strength of ceramics and the average splash velocity of fragments increase with the increase of loading strain rate.(2)The dispersion velocity of debris is related to its initial position.The dispersion velocity of peripheral debris is the largest.With the decrease of distance between initial position and central axis of the specimen,the dispersion velocity of debris decreases gradually.(3)With the increase of loading strain rate,the number of fragments produced by fragmentation increases gradually,and the corresponding average size of fragments decreases.The energy conservation and conversion mode in the compression crushing process of the specimen were further discussed,and the average velocity of debris splashing was theoretically analyzed.