Research Of 3D Displacement Measurement By White Light Digit Image Analysis In Frequency Domination Area And Its Application

2D measuring technique of white light digital image analysis in frequency domination area was developed and especially, when phaseshift method was introduced, all-automatic measurement of this method was realized. But 3D displacement and deformation of this method has not been developed, especially large deformation.In this paper, combining stereo photography,camera calibration method and white light digital image analysis in frequency domination area, the method for 3D displacement and deformation measurement by white light digital image analysis in frequency domination area was presented and used to measure dynamic and large deformation.Firstly, combining the principle of white light digital image analysis in frequency domination area, stereo photography and Tsai camera calibration method, the experimental method for 3D displacement and deformation measurement were presented in this paper. According to all-automatic measurement of white light digital image analysis in frequency domination area, displacement-projection method for 3D displacement and deformation measurement by white light digital image analysis in frequency domination was presented. Translation experiment and out-of-plane displacement measurement of all-round-fixed sheet were used to examine this method. The experimental results showed that the errors were acceptable.Secondly,the experimental method for camera calibration by white light digital image analysis in frequency domination area was presented. Combining white light digital image analysis in frequency domination area and a 3D precision adjusting device, a board coated with random speckle was used to calibrate cameras and 3D displacement and deformation measurement by this method was realized. The availability of this method was certified by the experiment of out-of-plane displacement measurement of all-round-fixed sheet.Finally, the compression deformation of thin-wall cylinder,Шtype crack stress intensity factor of engineering material and the deformation of rubber pipe which was pressed internally were measured. The experimental results show that this method is proper to measure dynamic, large deformation and little displacement. The accuracy of this method and some influencing factors such as image dimension, shooting angle, defocus and lens distortion were analyzed and the scope of application was studied.