| Photonic Doppler Velocimetry (PDV) is a new type of laser velocimetry system which has the advantages of non-contact measurement, high time resolution, high velocity resolution and non-sensitive to noise. It is widely used in the velocity measurement of the shock wave, detonation wave and other short-time high-velocity movement. An appropriate data processing method is needed, which purpose is to obtain the velocity information of the moving target from the measurement data mixed with a lot of noise. The PDV system was established, the velocity data of excitation units, Hopkinson pressure bar and the free surface of laser shocking was obtained by using it.This paper analyzes the principle and characteristics of several common PDV data processing methods. PDV data were processed using the fringe method, short time Fourier transform, Gabor transform, Wigner-Viller distribution and wavelet transform. It is shown that wavelet transform is particularly suitable to PDV data processing of laser shock peening experiment with high time resolution and high velocity resolution, short time Fourier transform has a limited resolution of time and velocity, fringe method is simple, high reliability, but difficult to handle, can only be used as the reference, Gabor transform and Wigner-Willie distribution is not suitable for a software processing program with a poor adaptability. The errors, real-time processing and resolutions about fringe method, wavelet transform and short time Fourier transform are compared. The sources and characteristics of noise about PDV data obtained from laser shock peening experiment are discussed. Some unique methods are proposed to eliminate noise, wavelet function selection and extraction of the velocity curve. The PDV data processing software is written in matlab software. With processing of three different velocity data of excitation units, Hopkinson pressure bar and the free surface of laser shocking, it is proved that our software is feasible and comprehensive. |
PDF Full Text Request