Analysis of complex stress intensities for cracked laminates

Classical plate theory has been used to find out interfacial stress intensity factors in composite laminates. By using a well-known relation between the crack-tip energy release rate and the complex stress intensity factor, a closed-form solution for complex stress intensity in terms of external loading and a mode mix parameter for fairly general composite laminates is given. Then a procedure for determining this mode mix parameter is presented, followed by numerical results for some laminates. Small scale contact condition is expressed in terms of external loading. In particular, a symmetric property of interfacial toughness curve is proven. Finally, the accuracy of failure load predicted by eliminating oscillation index is discussed, and an example is presented to show the validity and limitation of the =0 approximation.