JLA Vol:18 Iss:2 (A high power diode laser-based technique for the bonding of composite patches to aluminium alloys on various military aircraft)
Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Leicestershire LE11 3TU, England
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 inbetween 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 h crack growth rate that was rated as very good (1.9±0.5 mm/h); for the induction welded samples the 1 h 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 min when employing induction welding to 2.75 min 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.