Authors: S Ri T Muramatsu M Saka K Nanbara D Kobayashi
Publish Date: 2011/04/07
Volume: 52, Issue: 4, Pages: 331-340
Abstract
Measuring accurate displacement distributions for largescale structures is an important issue and a very challenging task Recently a simple and accurate phase measurement technique called sampling moiré method Exp Mech 50–4501–508 2010 has been developed for smalldisplacement distribution measurements In this method the phase distribution of moiré fringes can be analyzed from a single grating image by simultaneously performing downsampling image processing and intensityinterpolation to generate multiple phaseshifted moiré fringe images In addition the phase of the original grating can also be obtained from the phase of the moiré fringe by adding the phase of the sampling grating In this study the measurement accuracy of the sampling moiré method was analyzed through computer simulations and a displacement measurement experiment Four factors of the sampling moiré method were investigated including the sampling pitch the order of the intensityinterpolation random noise and the form of grating The results show that determining the optimal sampling pitch is an important factor for obtaining better results but it is not critical In addition a practical application of the sampling moiré method is presented that involves a deflection measurement on a 10meterlong crane The experimental results demonstrate that submillimeter deflections of the crane can be successfully detected
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