Collision measurements using digital image correlation techniques

In this study, the digital image correlation (DIC) techniques have been used to analyze the motion during the collisions. The spline interpolation along with two dimensional Fast Fourier Transform (FFT) cross correlation has been used in order to increase the accuracy and decrease the computation time of the method respectively. Three different examples have been analyzed: normal impact of a metal rod with a 3D printed polymer flat, oblique impact of a tennis ball with a tennis racket, and oblique impact of a lacrosse ball with a wooden flat. A speckle pattern study has been done to find the optimum pattern for the DIC technique. For the normal impact of the rod, the velocity during the impact have been measured. The normal velocity has been found by the DIC technique. For the oblique impact of the balls, the linear and angular motion have been calculated during the impact. The velocity field on the ball surface has been measured using the DIC technique. The Hough transform method has been used in combination with the measured velocity field to find the velocity of the centroid of the balls. The angular velocity during the impact has been found using the velocity field of the surface of the ball. It has been shown that the DIC technique can be used to measure the motion of colliding objects. (C) 2017 Elsevier Ltd. All rights reserved.