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°, and b) between 45° and 152°. 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°, 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° and 152°. 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.