99氧化铝陶瓷在不同应变率下的破碎特性

开展了99氧化铝陶瓷在不同应变率下的轴向压缩实验,通过对相应应变率下的试件碎片进行软回收,并结合筛余法对碎片进行几何表征,获得了不同应变率下的碎片尺寸分布曲线和试件破坏的能量吸收过程,建立了颗粒陶瓷的外力功与相对破碎率之间的关系。采用数字图像相关(Digital image correlation,DIC)技术获取了不同应变率下沿加载方向的应变场,并结合能量吸收过程和碎片级配表现分析了破坏模式。实验结果表明:99氧化铝陶瓷的破坏强度与应变率呈正相关,在中应变率下,能量吸收率与应变率呈负相关,由于能量吸收机制的改变,样品初始为劈裂破坏;当应变率达到401 s^?1时,破坏模式变为劈裂-粉碎混合破坏;随着应变率继续增大,试件变为粉碎破坏,颗粒平均粒径减小,碎片尺寸趋同,应力集中的影响逐渐减弱。分析了能量、破坏过程、碎片分布之间的关系,最终获得了碎片分布规律以及破碎特性。

Crushing Characteristics of 99 Alumina Ceramics under Different Strain Rates

In this study,axial compression experiments of 99 alumina ceramics at different strain rates were carried out.After soft recovering of the fragments at the corresponding strain rates,and geometrical characterization of the specimen fragments by the sieve residue method,the fragment size distribution curves at different strain rates as well as the energy absorption process in the failure of the specimen were obtained,and the relationship between the external force of the granular ceramic and the relative crushing rate was also established.Digital image correlation(DIC)technology is used to obtain the strain field along the loading direction at different strain rates,and the failure mode is analyzed in combination with the energy absorption process and fragment grading performance.The results show that the fracture strength of 99 alumina ceramics is positively correlated with the strain rate.At the middle strain rate,the energy absorption rate has a negative correlation with the strain rate.Due to the change of the energy absorption mechanism,the sample was fractured at the beginning,but the failure mode became split-crushing mixed failure when the strain rate reached 401 s^-1.With the strain rate increasing,the specimen became crushed and damaged.The average particle size decreases,the size of the fragments converges,and the influence of stress concentration gradually weakens.The relationship among energy,destruction process and fragment distribution was analyzed,and finally the fragment distribution law and fragmentation characteristics were obtained.