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Measurement of interfacial fracture parameters using coherent gradient sensing (CGS)
Author(s) -
Tippur Hareesh V.,
Xu Li Ming
Publication year - 1995
Publication title -
strain
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.477
H-Index - 47
eISSN - 1475-1305
pISSN - 0039-2103
DOI - 10.1111/j.1475-1305.1995.tb00978.x
Subject(s) - shearing interferometer , interferometry , materials science , shearing (physics) , optics , shearography , finite element method , stiffness , stress intensity factor , reflection (computer programming) , fracture mechanics , structural engineering , composite material , physics , astronomical interferometer , engineering , computer science , programming language
An optical interferometry called coherent gradient sensing (CGS) has been extended for mapping interface crack tip fields and for evaluating fracture parameters. The optical technique is a double grating shearing interferometer with an on line spatial filtering arrangement. The method offers real time full field measurements and can be used both in transmission made and reflection mode. The interferometer measures small angular deflections of light rays which can be further related to in plane gradients of s̀ x + s̀ y in transmission through elasto‐optic relations. Direct interfacial crack tip measurements in a high stiffness mismatch PMMA‐aluminium bimaterial system are performed. A variety of crack tip mode mixities are studied using asymmetric four point bend specimens subjected to different far field mechanical loads. The. complex stress intensity factors and the associated phase angles are measured from CGS patterns using an asymptotic expansion field. The measurements are compared with finite element results.