Crack-tip isochromatic and isopachic fringes at a bi-material interface

The optical evaluation of the stress intensity factors and the distribution of the principal stresses from isochromatic and isopachic fringes is presented. The, stress intensity factors and the principal stresses at the bi-material interface crack-tip are experimentally determined using the comparison photoelastic and isopachic measurements. The size and the shape of crack-tip isochromatic and isopachic fringes, at a bi-material interface under static load, are studied. When the crack-tip, which is perpendicular to interface, is at the interface of the bi-material, the isochromatic and the isopachic fringes depend on the properties of the two materials. Thus, the isochromatic and the isopachic fringes are divided into two branches. The size of the two branches mainly depends on the elastic modulus and the Poisson's ratio of the two materials.