[abstFig src='/00290003/16.jpg' width='300' text='The changes impact force to the sheet' ] A method for measuring the impact response of a polyurethane sheet is proposed. In the method, the velocity, acceleration, force, and displacement of a spherical body dropping onto the polyurethane sheet is measured using an optical interferometer. Only the velocity is measured from the Doppler shift of the laser light reflected on the cube corner prism embedded inside the spherical body. The optical center of the cube corner prism is made to coincide with the center of gravity of the whole spherical body to minimize the effect of the attitude change of the body. The acceleration, displacement, and inertial force of the body are calculated from the velocity. The dropping body is also observed using a high-speed camera. The uncertainty in measuring the instantaneous value of the impact force with a sampling interval of approximately 0.1 ms is estimated to be 0.23 N, which corresponds to 0.14% of the maximum force of approximately 1.60×102N. In the experiment, 10 drop measurements are conducted and show good reproducibility of this method.
In this paper, the Doppler shift of light is used to manipulate the change in optical path length using the classical interferometer. From which, the change in optical path length is related to the change in impact force, where finally the last of impact force can be related to the gel sheet absorption.
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