A comprehensive photoelastic study for mode I sharp V-notches

The method of photoelasticity is used to study the effects of first non-singular stress term on isochromatic fringe patterns around the tip of a mode I sharp V-notch. Notches are divided into two categories: notches with opening angles a) less than 45 degrees, and b) between 45 degrees and 152 degrees. First, utilizing the mathematical relations of the isochromatic fringes, the effects of the first non-singular stress term on the shape and size of the fringes are studied theoretically. For notch opening angles less than 45 degrees, it is shown that the isochromatic fringes rotate forward and backward when the coefficient of the first non-singular term is negative and positive, respectively. It is also demonstrated that both backward and forward rotations of fringe patterns are possible when the notch angle is between 45 degrees and 152 degrees. For all notch opening angles, as the first non-singular term dominates the notch tip stress field, a new type of fringe appears far from the notch tip. In order to evaluate the analytical findings, a photoelastic test program is also performed on a centrally notched cruciform specimen. Using this specimen, different loading conditions are simulated by changing the lateral load ratio and consequently different effects of the first non-singular term on the shape and size of the fringes are investigated experimentally. Good correlation between the analytical and experimental results is observed. (C) 2012 Elsevier Masson SAS. All rights reserved.