变截面舵面结构全场瞬态变形测量及振动特性分析

Full Field Transient Deformation Measurement and Vibration Characteristics Analysis of Variable Section Rudder Surface Structure

搭建了一套全场非接触应变测量系统,对变截面舵面结构受随机载荷激励作用下的变形及振动特性进行实验研究;实验以2A12铝合金材料制成的变截面舵面结构为试验对象,采用高分辨率的相机记录舵面结构全场清晰的散斑图像,然后利用三维数字图像相关方法对其结构表面的连续变形进行直接测量,同时利用傅里叶变换对采集到的散斑图像进行振动特性分析,获得变截面舵面结构的模态频率和模态振型;为验证非接触测量得到的振动特性结果的准确性,用小质量加速度传感器得到的振动响应信号进行对比;试验结果表明,在0~500 Hz的测试频段内,三维数字图像相关方法辨识变截面舵面结构前三阶模态参数与加速度传感器测量结果非常吻合,前三阶固有频率误差在2%以内,阻尼比误差在6%以内,前二阶模态振型均为弯曲模式,第三阶模态振型为弯曲扭转耦合模式,验证了三维数字图像相关的全场振动测量技术的有效性,为高温环境及非线性变截面舵面结构非接触振动测试提供依据。

A system of full field non-contact strain measurement is established to experimentally study the deformation and vibration characteristics of variable section rudder surface structure under random excitation load.Taking the variable section rudder surface structure made of 2A12 aluminum alloy as the test object,a high-resolution digital camera is used to record the clear speckle image of the structure in the whole field,and then the continuous deformation of the structure surface is directly measured by the three-dimensional digital image correlation method(DIC).At the same time,the vibration characteristics of the collected speckle image are analyzed by Fourier transform method,the modal frequencies and modal shapes of the variable section rudder surface structure are obtained.In order to verify the accuracy of the vibration characteristic results obtained by the non-contact measurement,it is compared with the vibration response signal obtained by using a small mass normal temperature acceleration sensor.The test results show that in the test frequency band of 0~500 Hz,the first three-order modal parameters of variable section rudder surface structure identified by three-dimensional digital image correlation method are very consistent with the measurement results of acceleration sensor.The error of the first three-order natural frequency is less than 2%,the error of damping ratio is less than 6%,the first two-order modal modes are the bending mode,and the third-order modal mode is the bending torsional coupling mode,The effectiveness of the full field vibration measurement technology based on three-dimensional digital image correlation is verified,which provides a basis for the non-contact vibration measurement of nonlinear variable section rudder surface structure in high temperature environment.