G. Dearden*, M.C. Simmons**, P.Okon*, G.K. Schleyer** & K.G. Watkins*
Laser in Engineering Group* & Impact Research Group**,
Department of Engineering, University of Liverpool, L69 3GH, United Kingdom.
Abstract: The paper presents some results from a study being undertaken at Liverpool into the application of laser welding technology to the design and fabrication of blast and impact resistant structures in the transportation industries. A novel facility has been developed at Liverpool for analysis of dynamic pressure loading of structures, such as aircraft fuselage panels. In the initial work to compare riveted and laser welded panels, the study has included experiments to lap weld AA2024-T3 sheet with both CO2 and YAG lasers, initial dynamic loading tests on a riveted panel, quasi-static and uniaxial tensile tests on laser welded and riveted AA2024-T3 specimens and FE modelling of the trial riveted structures under loading. In conclusion, more consistent weld penetration on lap joints of 1.6mm thick alloy were obtained with a 3.5kW Nd:YAG laser, than a CO2 laser of equivalent power. Initial tests on a riveted panel identified some boundary conditions and failure loads for future tests. Uniaxial tests on laser welded and riveted specimens of AA2024-T3 indicated that the laser-welded joints have higher strength per unit joint length than the riveted ones, but exhibit more brittle failure. For the initial test panel, failure under dynamic loading occurred at a peak pressure of only 0.6 bar. The FE models of the preliminary tests compare well with experiment, based on mid-panel displacement measurements, but need further development to account for weak points in the frames where the test panel eventually failed.