基于SLDV技术的薄壁机匣三维全场模态测试方法

Three-dimensional full-field modal test method for thin-wall casing based on SLDV technique

提出了基于扫描式激光多普勒测振(SLDV)技术的薄壁机匣模态测试方法,实现了薄壁机匣的三维全场振动测试。基于LDV(laser Doppler vibrometry)测试原理,建立了机匣结构分片三维激光测量方法和拼接技术,实现了三维激光测试数据的处理,准确识别出了机匣的各阶模态参数,并与传统加速度传感器获取的测试结果进行了相关性分析。分析结果显示:两种测试结果的模态振型NCO(normalized cross orthogonality)值均在0.9左右,频差较小,验证了薄壁机匣扫描式激光多普勒三维全场测试的可行性和优越性。

A modal test method of casing was proposed based on scanning laser Doppler vibrometry(SLDV),and the 3D full-field vibration measurements of thin-wall casing were completed by studying laser Doppler vibrometry(LDV)measurement principle.A 3D laser measurement method for measuring each part of casing independently and a modal splicing technique were established,the data measured by 3D laser was processed and the modal parameters of casing were identified accurately.Modal correlation between SLDV measurement modes and conventional acceleration sensor measurement modes was analyzed.Results showed that normalized cross orthogonality(NCO)values were about 0.9 and the frequencies difference was very small,validating the feasibility and advantage of using the SLDV to measure the 3D full-field vibration of thin-wall casing.