结构光投影和条纹时间平均分析技术已被用于振动模式分析中,但由于投影单色正弦条纹时振动薄膜变形条纹傅里叶谱中零频涵盖范围较大,会限制滤波窗的选取范围,从而影响模式的最终重建结果。为提高振动模式重建的准确性,提出了一种利用π相移正弦条纹投影进行薄膜振动模式分析和振幅重建的方法,通过处理两个通道的条纹分量达到消除零频的目的。给出了该方法的理论分析,完成了相应的计算机模拟,分析了影响测量精度的因素。通过与投影单色正弦条纹的振动模式重建结果对比,表明该方法有较高的重建精度。不同激励频率下的实际薄膜振动实验结果也证明了该方法正确可行。

Structured light projection and time-average fringe method is used in vibration mode analysis. When a monochromatic sinusoidal grating is projected onto the surface of a vibrating membrane, the zero component in Fourier spectrum domain of the corresponding deformation fringe pattern would extend to a large range and increase the difficulty of filtering window selection, which would finally influence the accuracy of the mode reconstruction result. A method by projecting π phase shifting bi-color sinusoidal fringe in vibration mode analysis and amplitude reconstruction of a vibrating membrane is presented in this paper to improve the accuracy of vibration mode reconstruction. The zero component of Fourier spectrum is eliminated by processing the fringe components in two color channels. The result of theoretical analysis and computer simulations show that the proposed method in this paper can effectively improve the reconstruction accuracy of the vibration mode by comparing with the method using a monochrome sinusoidal fringe projection. The actual experimental results of a tested vibrating membrane excited by different vibration frequencies also identify the validity of this method.