The phase angle of an interface crack induced by indentation delamination with buckling

Abstract

In the indentation delamination test, an indentation load generates a compressive stress field to delaminate a film from its substrate and the interfacial fracture is always of a mixed mode. The interfacial fracture toughness depends on the phase angle of the fracture mixed mode. If the delaminated film buckles, the buckling induces a tensile stress field and thus changes the phase angle and the measured value of interfacial fracture toughness. A simple equation was derived to calculate the phase angle. Based on the simple equation and the empirical formula, which describes the interfacial fracture toughness as a function of the phase angle, relations among interfacial fracture toughness, phase angle and indentation load/cracklength are discussed in details. © 2007 Springer.