航空钛合金板胶接表面粗糙度的超声测量

Improved Pulsed Ultrasonic Spectroscopy for Adhesive Surface Roughness Measurement of Aerial Titanium Alloy Plates

采用一种新的超声频谱法快速测量航空钛合金板经喷砂预处理后的胶接表面粗糙度,并引入表面面积均方根粗糙度系数ST来表征材料表面三维微观形貌.以航空Ti-6Al-4V钛合金胶接板为测量试样,超声换能器接收测试试样表面的反射回波,并计算得到AR参数谱.以反射脉冲AR参数谱和声波镜面反射理论为基础,建立了有关脉冲波声反射系数和表面均方根粗糙度系数ST的数学模型.利用表面粗糙度系数理论模型.数值计算反射回波的理论频谱曲线,并与实测反射回波AR谱进行拟合.利用最小值搜索算法,处于最佳拟合时的表面粗糙度系数ST即为试样胶接表面的测量结果.实验表明,超声反射频谱法测量结果与轮廓仪测量结果符合得很好,该测量方法在材料或零部件表面粗糙度在线测量中具有广泛的应用前景.

A new ultrasonic spectroscopic technique has been developed to fast assess the adhesive surface roughness of aerial titanium alloy that was pretreated by grit blasting. A surface area roughness coefficient SThas been introduced to specify the 3D topography of a material surface on a quantitative basis. Comprehensive theoretical models based on analyzing the AR parameter frequency spectrum of the received ultrasonic signals have been developed to study the effect of surface roughness on reflected ultrasonic pulses from the rough surface of titanium alloy （Ti-6Al-4V）. When the transducer received a pulse reflected from the titanium alloy surface of the sample, the AR parameter spectrum was compiled. The computer then generated a theoretical curve to match the profile of the spectrum using a theoretical model for surface roughness and a minimization algorithm. The resulting value of the roughness coefficient ST, representing the best match, was a measure of the surface roughness. The experimental results show that the measured values of ultrasonic spectroscopy and those of depth profilometer have good consistency, and that the new ultrasonic spectroscopic technique can be widely useful to on-line measurement of surface roughness of materials or components.