An advanced numerical tool to study fatigue crack propagation in aluminium plates repaired with a composite patch

In this study, fatigue crack growth behaviour of a cracked thick aluminium-alloy plate repaired with a bonded composite patch is investigated. An adhesively bonded composite-patch repair technique was successfully applied to military-aircraft repair and recently extended to commercial aircrafts. Also this technique has been extended its application from secondary structure repair to the repair of load bearing structures and components. Thus, a thorough understanding of crack growth behaviour of a thick panel repaired with a bonded composite patch is needed. Such behaviour is investigated in this paper using a finite-element code Zencrack in combination with ABAQUS. This approach enables a user to determine the crucial fracture-mechanics parameters such as stress intensity factors. Furthermore, a damage model was implemented for the adhesive layer, in order to monitor the consequence of a partial or total loss of adhesion on crack propagation in the repaired aluminium plate.