Spontaneous Mixed-Mode Fracture in Bonded Similar and Dissimilar Materials
In this paper, we report on an experimental study of spontaneous, mixed-mode, crack propagation in weakly bonded similar and dissimilar materials. A unique experimental configuration is proposed to induce spontaneous crack growth events along the interfaces. The cracks nucleate from tiny circular holes and are triggered by an exploding wire. They subsequently propagate under the action of a constant, far-field load. Dynamic photoelasticity in conjunction with high speed photography is used to capture the real-time isochromatics associated with crack propagation. In the case of identical materials, crack propagation is anti-symmetric with respect to the crack nucleation point while strong asymmetry is observed for the case of dissimilar materials. In both cases, cracks propagate at constant velocity from the initiation point. The time histories of dynamic stress intensity factors and of energy release rates of the propagating cracks along the bonded similar materials are also reported.
© 2006 Society for Experimental Mechanics. Received: 30 June 2005; Accepted: 29 November 2005. From the issue entitled "Special issue on Failure of Heterogenous Materials." The authors would like to acknowledge the support of the Office of Naval Research (ONR) through grant number N00014-03-1-0435 (Dr. Y.D.S. Rajapakse, project monitor). Helpful discussions with Prof. G. Ravichandran from Caltech, with Prof. A. Shukla from University of Rhode Island and with Prof. L.B. Freund at Brown University are also acknowledged.