Coating Interface Fracture Toughness Evaluation by a Combination of Edge Compression and Slinging Load

Abstract

Previous methods to measure interface fracture toughness between coating and substrate can't easily vary a phase angle as a mixed mode parameter. So that, the new coating interface fracture toughness test method, by which phase angle at interface crack tip can be varied due to applying a combination of compression loading to the coating edge and slinging such as beam bending, is proposed. The simple formula, which connects to complex stress intensity factors and double loading is firstly derived on the basis of the cracked beam model proposed by Suo and Hutchinson [1]. As an application of the method and associated formula, thermal barrier coating/super-alloy interface toughness is evaluated based on numerical analysis.