An interferometric and finite element investigation of interfacial crack tip fields: Role of mode-mixity on 3-D stress variations

The elasto-optic effects are mapped as (ax+a~) contours near interfacial cracks in polymer-metal bimaterials using Mach-Zehnder interferometry. The stress fields are investigated when the crack planes are subjected to dominant tensile stresses and pure shear stresses. The optical measurements are examined in conjunction with companion finite element simulations for estimating the regions of dominant three dimensional stress variations near cracks. Results suggest that in the domain (x, y > 0) the size of the region of dominant three dimensional effects is significantly smaller for the case of pure shear ( for both positive and negative shears) when compared to the tensile stress dominated case for oscillation index ~ > 0. The optical data analyzed by incorporating these observations improve the accuracy of crack tip parameter estimation. Copyright © 1997 Elsevier Science Ltd.