基于声发射特征参数的泡沫铝低周疲劳过程研究

Study on low-cycle fatigue process of aluminum foam based on acoustic emission characteristic parameters

使用声发射仪和CCD相机采集了室温下闭孔泡沫铝试样单轴压缩和正弦波恒载疲劳试验过程的声发射参数及CCD图像,得到了单轴压缩时的声发射参数与应力-应变曲线及不同峰值应力(最大应力/屈服应力)下疲劳寿命曲线和声发射特征参数。结果表明:声发射振铃计数的变化与泡沫铝的应力-应变曲线和疲劳曲线变化趋势一致。通过对声发射振铃计数与能量计数的分析,低峰值应力下,泡沫铝孔壁以周期性弹性变形为主,同时,随着累积应变的增加,局部出现塑性变形及坍塌;高峰值应力下泡沫铝孔壁变形以塑性变形为主,且局部出现坍塌;随着峰值应力的增加,疲劳寿命降低。

The acoustic emission(AE)parameters and CCD images of closed-cell aluminum foam samples at room temperature during uniaxial compression and sinusoidal fatigue tests under constant load were collected using acoustic emission equipment and CCD camera.AE parameters and stress-strain curves under uniaxial compression,fatigue life curves and acoustic emission characteristic parameters under different peak stresses(ratio of maximum stress to yield stress)were obtained.The results show that the variation of AE bell count is consistent with the variation of stress-strain curves and the fatigue curves.Through the analysis of AE bell count and energy count,periodic elastic deformation is the main deformation of aluminum foam under low peak stress.At the same time,plastic deformation or slumping occurrs locally with the increase of cumulative strain.Plastic deformation is the main deformation mechanisium of aluminum foam under high peak stress and local slumping occurs.The fatigue life decreases with the increase of peak stress.