Moire interferometry

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Moire interferometry is accomplished by first bonding a clear plastic film, marked with closely spaced lines, to the specimen. A second sheet, similarly marked, is then placed over the first but without bonding or electrostatic coupling. During incremental static loading, the bonded layer deforms while the second, unbonded layer, does not. Consequently, some lines will super-impose while others overlap (the so-called Moire effect). Lines of equal displacement appear which can be photographed or transformed to strains and stresses. The technique is inexpensive (less than 1000 for equipment and materials), but limited in application because significant curvature can not be accommodated. 

Moire interferometry is used to measure tiny deformations of solid bodies, caused by mechanical forces, temperature changes, or other environmental changes [20]. It has been appUed for studies of composite materials, polycrystalline materials, layered materials, piezoelectric materials, ffacmre mechanics, biomechanics, stmctural elements and stractural joints. It is practiced extensively in the microelectronics industry to measure thermally induced deformation of electronic packages. Moire interferometry combines the simplicity of geometrical moire with the high sensitivity of optical interferometry, measuring in-plane displacements (Fig. 12.12). It is characterised by a list of excellent qualities. Moire interferometry has a proven record of applications in engineering and science. 

Fig. 12.12 Schematic diagram of four-beam moire interferometry [20]...

Post D, Han B (2008) Moire interferometry. In Shaipe WN Jr. (ed) Springer handbook of experimental solid mechanics. Springer, Berlin, pp 627-645 (ISBN 978-0-387-26883-5)... 

Moire interferometry and digital image correlation are the most popular non-contact strain-measuring methods. Both are based on optical principles. 

Han B, Post D and Ifju P (2001), Moire interferometry for engineering mechanics Current practices and future developments , J Strain Anal Eng, 36(1), 101—117. 

Post D (1993), Moire interferometry , in. Kobayashi A S (ed) Handbook on Experimental Mechanics, New York and London VCH Publishers. 

Post D and Han B (2008), Moire interferometry , in Sharpe W N (ed) Springer Handbook of Experimental Solid Mechanics, New York Springer Science + Business Media. 

Wood J (1985), Detection of delamination onset in a composite laminate using moire interferometry , J Compos Tech Res, 1, 121-128. 

YB02CU3O, Shadow Moire interferometry Residual stress. Dependence on position Wu(1993)... 

Fanucci, J. R, Mar, J.W. Fatigue Damage Detection in Thin Composite Laminates Using Out-of-Plane Moire Interferometry, Journal of Composite Materials, 16 (1982), p. 94- 102... 

Tsai and Morton (1995) studied the influence of a triangular spew fillet in laminated composite single-lap joints. The FE analysis and the experimental tests (Moire interferometry) proved that the fillet helps to carry part of the load, thus reducing the shear and peel strains. 

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