ass日本风韵熟妇pics男人扒开女人屁屁桶到爽|扒开胸露出奶头亲吻视频|邻居少妇的诱惑|人人妻在线播放|日日摸夜夜摸狠狠摸婷婷|制服 丝袜 人妻|激情熟妇中文字幕|看黄色欧美特一级|日本av人妻系列|高潮对白av,丰满岳妇乱熟妇之荡,日本丰满熟妇乱又伦,日韩欧美一区二区三区在线

The frequency domain of ultrasonic pulse echo signal obtained from carbon fiber reinforced polymer (CFRP) was studied. First the frequency domain feature of reflection coefficient for the fiber layer and resin layer in CFRP laminate was analyzed. The result shows that normal and porous fiber layer, and normal and thick had different influence on the acoustic reflection coefficient. Based on the result above, the frequency domain model for the pulse echo signal acquired from CFRP laminate was established. The pulse echo signal spectrum was composed of normal fiber/resin layer response, porous fiber layer response, thick resin layer response, probe response and noise signal response. Then the numerical simulation of CFRP laminate was implemented based on the model. The simulation signal spectrum of CFRP laminate with voids as well as the spectrum of CFRP laminate without voids was obtained. The results show that the simulation signal spectrums had the same main frequency components with the corresponding experimental signal spectrums.