Experimental and numerical approach in fatigue life prediction for an Al 8090 helicopter bolted joint

Abstract: Aerospace structures need excellent structural efficiency. The advantages of Al-Li alloys over conventional aluminium alloys include relatively low densities, high elastic modulus, excellent fatigue and toughness properties, and superior fatigue crack growth resistance due to crack closure. Unfortunately, these alloys have some disadvantages when subjected to compressive loading conditions. Moreover, mechanical properties are also often highly anisotropic and present a very high crack growth rate for microstructurally short cracks, which potentially allow for fast crack nucleation. This could mean relatively early cracking in high stress regions such as rivet holes. The 8090 T81 aluminium alloy has been widely used in some helicopters, in particular in the bolted connection between the stringers and the modular joint frame in the rear of the fuselage. The aim of this work is to investigate the fatigue behaviour of this joint with both experimental tests and numerical anal..