2A12铝合金临界损伤值测定及试验验证

Measurement and experimental validation of critical damage value for 2A12 aluminum alloy

基于Normalized Cockcroft&Latham损伤准则,采用Gleeble Fracture Limit(GFL)试验方法测定了2A12铝合金在常温及应变速率为0.01、0.1、1和5 s^-1条件下的临界损伤值,研究了应变速率对2A12铝合金临界损伤值的影响。为验证试验测定的临界损伤值的准确性,以应变速率1 s^-1为例,利用高速摄像系统以100 fps的速度原位观测缺口试样在压缩过程中的动态损伤开裂行为,标定了裂纹萌生时刻的临界变形量为57.2%,结合数值模拟方法反推试样达到临界变形量时的最大损伤值即为材料的临界损伤值。结果表明,GFL试验测定的临界损伤值与数值模拟得到的临界损伤值的相对误差为0.3%,因此采用GFL试验方法测定的临界损伤值比较准确。

Gleeble Fracture Limit(GFL)test method was adopted to acquire critical damage values of 2A12 aluminum alloy at room temperature and strain rate of 0.01,0.1,1 and 5 s^-1based on Normalized Cockcroft&Latham damage criterion,and the effect of strain rates on critical damage value of 2A12 aluminum alloy was also investigated.To verify the accuracy of the critical damage values measured by the GFL tests,the strain rate of 1 s^-1was taken as an example and the dynamic damage cracking behavior of the notched specimen during compression was observed in-situ by high-speed camera system at 100 fps.The critical deformation at crack initiation was 57.2%.Combined with the numerical simulation,the maximum damage value was obtained when the sample was compressed to the critical deformation,which was the critical damage value.The results show that the relative error between the critical damage value measured by GFL test and by simulation is 0.3%.Therefore the critical damage values measured by GFL tests are more accurate.