A high power diode laser (HPDL)-based technique for the bonding of composite patches to aluminium alloys on various military aircraft

Abstract

A rapid, effective and repeatable technique for repairing the damaged skins of various military aircraft, both fixed and rotary winged, using high power diode laser (HPDL) radiation is described herein. The HPDL beam was traversed across the surface of an APC-2 repair patch, thereby melting a thermoplastic adhesive placed in between the repair patch and an Alclad substrate, consequently bonding the repair patch to the Alclad substrate. When subjected to single lap shear tests, the shear strength of the bond generated with the HPDL radiation was 47.8 ± 4.7 MPa, compared to 32.4 ± 3.7 MPa for the induction welded samples. When subjected to the Boeing wedge test, the HPDL samples had a 1 hour crack growth rate that was rated as very good (1.9 ± 0.5 mm/h); for the induction welded samples the 1 hour crack growth rate that was rated as good (2.7 ± 1.2 mm/h). Of great significance was processing time achieved with the HPDL, which was reduced from 11.75 minutes when employing induction welding to 2.75 minutes with the HPDL. Moreover, the use of HPDL radiation has been shown in this work to be an effective means for bonding that is superior to its contemporary counterparts