铝合金在不同应力状态下微损伤演化的声发射研究

Study on the micro-damage evolution of aluminum alloy under different stress states based on acoustic emission

利用声发射技术对不同应力状态下铝合金的微损伤演化规律进行试验研究。首先,对铝合金在正断和切断两种断面取向的试样进行单轴拉伸试验,并同时采集微损伤声发射信号;其次,基于所采集的微损伤声发射信号构建了一个能够表征微损伤能量尺度特征和时间序列特征的随机损伤变量,进而通过对该随机变量的分析来研究铝合金在不同应力状态下的微损伤演化特征;最后,通过计算随机损伤变量在不同外载荷水平下的概率熵给出描述材料微损伤演化过程的一种表征。通过试验并辅以对断面的扫描电镜观测获得的结果是,同一种铝合金材料在两种不同应力状态下获得的微损伤概率熵曲线具有显著差异性,而在相同应力状态下分别针对铝合金材料1060和6063的微损伤概率熵曲线又具有一致性。上述研究结果可为探索铝合金在不同应力状态下的微损伤演化规律提供参考。

Acoustic emission experiments are performed to investigate the micro-damage evolution properties of aluminum alloy under different stress states. Firstly, uniaxial tensile tests are implemented for aluminum alloy specimens with tensile and shear orientations respectively, and the acoustic emission signals stemmed from the micro-damage of aluminum alloy are collected in the same time. Secondly, based on the collected acoustic emission signals, a stochastic variate is defined to characterize the multiscale property and the time-series property of the released energy caused by the micro-damage in aluminum alloy. Finally, a probabilistic entropy is calculated from the derived multivariate to describe the micro-damage evolution process of aluminum alloy quantitatively. The results of acoustic emission tests, combined with the scanning electron microscope observation of the specimen's fracture surfaces, show that the curve of probabilistic entropies can effectively distinguish the significant difference of micro-damage evolution of the aluminum alloy under two kinds of stress states. Moreover, the curves of probabilistic entropies for two different kinds of aluminum alloy materials, i.e. aluminum alloy 1060 and aluminum alloy 6063, are consistent under the same stress states. The present results could benefit the understanding of micro-damage evolution of alumina alloy under different stress states.