EVALUATION OF RIGID ROTATIONS IN FLEXURAL LOADING TESTS BY HOLOGRAPHIC-INTERFEROMETRY

The authors develop a simple method based on holographic interferometr y for determining the Poisson's ratio and the Young's modulus for a sp ecimen subjected to four-point flexural testing that evaluates and eli minates the effects of the unwanted rigid-body rotations. In the exper imental setup, they use an additional mirror to record the underside a nd the front surface of the specimen simultaneously. The theoretical a nalysis shows that it is possible to correlate the holographic fringe pattern of the underside and front surface of the sample. Each rotatio n angle can be evaluated by counting the fringe orders between two poi nts chosen on the two fringe patterns.