Effect of Initial Debond Crack Location on the Face/core Debond Fracture Toughness

Department of Mechanical Engineering, Technical University of Denmark, Nils Koppels Allé, 2800 Kgs. Lyngby, Denmark

^a e-mail : amq@mek.dtu.dk

Abstract

This paper studies the effect of initial crack location on the face/core debond fracture toughness under different mixed mode loading conditions. The mixed mode loading at the crack tip is defined in terms of the mode-mixity. In order to achieve the desired initial debond crack location, a pre-cracking technique is developed, where the mode-mixity, number of cycles, crack increment and load level are accurately controlled. Results show that the debond fracture resistance of foam-cored sandwich specimens depends on parameters such as loading condition (mode-mixity), core and face properties, as well as initial debond crack location. Lower fracture toughness values were measured for specimens with the initial crack location in the face laminate.