EVALUATION OF MODE I CRACK SUPPRESSION METHOD FOR FOAM CORE SANDWICH PANEL WITH FRACTURE TOUGHNESS TEST AND ANALYSES

摘要

An interfacial crack in a foam-core sandwich panel has a serious influence on its structural integrity. A new type of crack arrester is proposed for the suppression of interfacial crack propagation between the surface skin and the core of a carbon fiber reinforced plastic (CFRP)/foam core sandwich panel. The crack arrester is based on the concept that a different material with higher stiffness on the crack propagation path suppresses crack propagation. Finite element calculations were carried out to evaluate this concept using fracture mechanics parameters. A considerable reduction in the energy release rate at the crack tip was confirmed under a constant load of mode I type loading as the crack tip approached the crack arrester. The verification tests for mode I type loading were conducted using sandwich panel specimens with and without a crack arrester. The test results indicated that the crack arrester increased the critical load of the test specimen for mode I type loading, and an approximately 5 times larger critical energy release rate was obtained near the leading edge of the arrester owing to this new concept. Thus, it is considered that this newconcept crack arrester is a promising device for suppressing crack initiation and propagation for foam core sandwich panels.