载荷作用下泡沫铝的波速与变形关系的实验研究

Experimental Investigation on the Relation between Wave Velocity and Deformation of Aluminum Foam Subjected to Compression Load

对单轴压缩下两种密度的泡沫铝进行了三种频率(50kHz、200kHz和300kHz)的声波测试,同时运用CCD对实验进行跟踪拍摄。分析结果表明:P波波速随载荷增大而增加,当载荷达到屈服力时,波速有所下降;S波有相同趋势,但变化比P波小。应用数字图像相关方法对CCD拍摄图片进行处理,得到不同载荷阶段下泡沫铝的全场应变;采用Weibull函数对全场应变分布进行拟合,研究了Weibull分布参数随载荷变化的规律。由此,初步建立了载荷作用下材料结构变化与波速的关系。此研究对于声波探测领域有很好的指导意义。

Acoustic measurement of aluminum foam with two kinds of density and subjected to uniaxial compression was carried out,by using three frequencies（50kHz,200 kHz and 300kHz）respectively.Meanwhile,the tracking photography for experiment was also carried out by using CCD camera.Results indicate that the velocity of P wave increases with the increase of load;when load reaches the yield force,it decreases.S wave presents the similar variation trend,but the change is smaller than that of P wave.Images taken by CCD camera were treated by digital image correlation method;full strain field of aluminum foam on different loading stages was obtained. Weibull function was introduced to fit the full-field strain distribution,and the variation of Weibull distribution parameter with the increase of load was studied.From this,the relation between wave speed and micro-structure change of material subjected to load was preliminary established.Above results are potential for providing important guiding significance to acoustic detecting.