烧结钕铁硼一维应力层裂实验研究

Experimental Study on One Spalling of Sintered NdFeB under One Dimensional Stress Loading

利用分离式Hopkinson压缩试验装置(SHPB)进行烧结钕铁硼(NdFeB)试件的一维应力层裂实验。使用超高速摄影机并结合数字图像相关方法(DIC),获得了试件的变形与层裂过程描述,确定层裂位置及其应变,并用于计算层裂强度。采用激光测速技术,获得试件的自由面速度历史,并用于计算试件的层裂强度。利用SEM观察断口微观形貌,分析烧结钕铁硼的动态断裂机理。结果表明,在冲击速度8.6~24.7 m/s内,试件的层裂强度及层裂次数随冲击速度的增加而增加。由DIC获得的层裂区应变计算的试件层裂强度略高于使用自由面速度回跳计算的结果。

Based on split Hopkinson pressure bar(SHPB),the one-dimensional stress spalling tests of sintered NdFeB specimens were carried out.The failure process of the specimen was obtained by using ultra-high speed camera combined with digital image correlation(DIC).The location,localized strain and strength of spalling of the specimens were determined by DIC results.The free surface velocity history of the specimen was measured by laser velocimetry,and the spall strength of the specimen was calculated by free surface velocity pull-back.The dynamic fracture mechanism of sintered NdFeB was analyzed by SEM.The results show that the number and strength of the specimen spalling increase with the increase of impact velocity in the range of 8.6-24.7 m/s.The spall strength of the specimen determined by localized strain given by DIC is slightly higher than that calculated by free surface velocity pull-back.