基于DIC实验的空间域信号去噪方法研究

Research of Denoising Method of Signals in Spatial Domain Based on Digital Image Correlation Experiment

通过二维傅里叶连续延拓联合波数域低通滤波的方法,对数字图像相关测量所得位移场进行去噪重构,通过对薄板结构的工况模态分析,验证空间域信号去噪方法的有效性。数字图像相关方法测量结果为结构表面的全场位移响应,因相机本底噪声等因素的影响,由此在位移场测量结果中引入的空间域噪声不可忽略。通过对去噪重构后的时序位移场进行互相关函数计算,使用ERA算法辨识得到薄板的前5阶模态参数,与有限元计算模态结果吻合良好。

Through the method of two-dimensional Fourier Continuation combined with low-pass filtering in the wavenumber domain,the displacement fields measured by digital image correlation(DIC)are denoised and reconstructed.The effectiveness of spatial domain signal denoising method is verified by operational modal analysis of a thin plate structure.The measurement result of the DIC method is the full-field displacement response of the structure surface.Due to the influence of camera background noise and some other factors,the spatial domain noise introduced in the displacement field measurement result cannot be ignored.By calculating the cross-correlation function of the time-series displacement field after the denoising and reconstruction,the first five order modal parameters of the thin plate are identified by means of ERA algorithm,which is in good agreement with the modal results of finite element calculation.