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A hybrid experimental/computational approach to the assessment of crack growth criteria in composite laminates
Author(s) -
Walker C.A.,
Jam M.
Publication year - 1996
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.1475-1305.1996.tb01018.x
Subject(s) - structural engineering , materials science , radius , crack tip opening displacement , finite element method , crack closure , composite number , crack growth resistance curve , function (biology) , stress (linguistics) , mechanics , fracture mechanics , composite material , computer science , engineering , physics , linguistics , philosophy , computer security , evolutionary biology , biology
While a number of criteria have been proposed for predicting the onset of crack growth in composite laminae, there has hitherto been no accepted method of assessing the value of alternative proposals. This study integrates the use of computational modelling, along with moiré interferometry for the quantitative mapping of near crack tip deformation fields. The moiré method was used to validate the computational model. It was then possible to use the computational model on its own to predict crack tip behaviour in more detail than could be done with the optical system alone. This study chose one crack growth criterion ‐ the normal stress ratio ‐ to demonstrate the assessment routine. The value of the normal stress ratio (NSR) was calculated as a function of the ply angle to the loading direction. In order to obtain sensitive predictions of crack growth direction, it was desirable to proceed by analysing the crack tip behaviour down to radial distances from the crack tip of a few tens of microns. By a suitable choice of elements around the crack tip, the finite element model was able to predict values of the NSR down to a radius of 80 times10 ‐3 mm around the crack tip.