Hybrid determination of mixed-mode stress intensity factors on discontinuous finite-width plate by finite element and photoelasticity

Journal of Mechanical Science and Technology (Impact Factor: 1.09). 01/2011; 25(10):2535-2543. DOI: 10.1007/s12206-011-0740-1

ABSTRACT For isotropic material structure, the stress in the vicinity of crack tip is generally much higher than the stress far away
from it. This phenomenon usually leads to stress concentration and fracture of structure. Previous researches and studies
show that the stress intensity factor is one of most important parameter for crack growth and propagation. This paper provides
a convenient numerical method, which is called hybrid photoelasticity method, to accurately determine the stress field distribution
in the vicinity of crack tip and mixed-mode stress intensity factors. The model was simulated by finite element method and
isochromatic data along straight lines far away from the crack tip were calculated. By using the isochromatic data obtained
from finite element method and a conformal mapping procedure, stress components and photoelastic fringes in the hybrid region
were calculated. To easily compare calculated photoelastic fringes with experiment results, the fringe patterns were reconstructed,
doubled and sharpened. Good agreement shows that the method presented in this paper is reliable and convenient. This method
can then directly be applied to obtain mixed mode stress intensity factors from the experimentally measured isochromatic data
along the straight lines.

KeywordsPhotoelasticity–Polariscope–Stress intensity factor–Isochromatics–Isoclinics–Inclined crack–Mixed-mode stress intensity factor–Photoelastic fringe doubling–Fringe sharpening

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