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 (sigma(x) + sigma(y).) contours near interfacial cracks in polymer-metal bimaterials using Mach-Zehnd er interferometry. The stress fields are investigated when the crack p lanes are subjected to dominant tensile stresses and pure shear stress es. The optical measurements are examined in conjunction with companio n finite element simulations for estimating the regions of dominant th ree dimensional stress variations near cracks. Results suggest that in the domain (x, y > 0) the size of the region of dominant three dimens ional effects is significantly smaller for the case of pure shear (for both positive and negative shears) when compared to the tensile stres s dominated case for oscillation index e > 0. The optical data analyze d by incorporating these observations improve the accuracy of crack ti p parameter estimation. Copyright (C) 1997 Elsevier Science Ltd.