Damage tolerance analyses of bolt/nut assemblies

Probably one of the most challenging problems in fracture mechanics is related to its application to fastener and joints. By nature, not only the quality such as material, manufacturing and mounting processes, of the fasteners are playing a role, but also the stiffness, surface conditions and geometry of the parts are to be considered. Moreover,...

Flight simulation fatigue crack propagation evaluation of candidate lower wing skin materials with particular consideration of spectrum truncation

Flight simulation fatigu-e crack propagation tests were carried out on 2024-T3, 7475-T761 and mill annealed Ti-6A1-4V sheet in thicknesses up to 3 miri and representative for transport aircraft lower wing skin stiffened panels of end load capacities 1.5 and 3 MN/m. The performance of 2024-T3 was much superior, owing mainly to greater retardation...

The use of Arall in fuselage skins

The report starts with a general review of the loading of transport aircraft fuselages and the consequent fuselage skin stresses Taking the F-28 fuselage as an example, the potential weight savings that can be obtained by using ARALL as skin material are assessed. The report ends with conclusions and recommendations

Environmental fatigue crack propagation in metal/composite laminates

Flight simulation fatigue crack propagation tests with gust spectrum loading were carried out on 2024-T3/carbon-epoxy, 7475-T76l/carbon-epoxy and Ti-6Al-4V/carbon-epoxy laminates with nominal weight savings of -30% as compared to equivalent 2024-T3 panels. The performance of the 2024-T3/carbon-epoxy laminates was much superior to those of the...

The use of load enhancement factors in the certification of composite aircraft structures

In the full scale durability and damage tolerance tests of composite aircraft structures, the US and European certification requirements demand among other things that the number of cycles applied are statistically significant and that the influence of the environment has been taken into account. Several certification methods are described which...

The effect of gust alleviation on fatigue in 2024-T3 Alclad

Fatigue tests under flight simulation loading were done on simple notched 2024-T3 Alclad sheet specimens. Reduction of the gust load amplitudes resulted in an increase of crack initiation life but hardly influenced crack propagation. Reduction of the overall stress level increased both initiation and crack propagation life. The observed...

European approaches in standard spectrum development

Typical characteristics of various types of service loading are presented as they were discussed during the establishment of standardised test load sequences. Counting methods are reviewed and a simple and powerful algorithm is given to perform rainflow counting and to store the counting results afterwards. Synthesis procedures are discussed...

Heat treatment studies of aluminium alloy forgings of the AZ 74.61 type. Interim report no. 3: Fatigue crack propagation performance under manoeuvre spectrum loading

The fatigue crack propagation performance of the alloy AZ 74.61 under manoeuvre spectrum loading was studied. The crack propagation behaviour was also compared with that of the American forging alloy AA 7050, not only for simulated manoeuvre loading but also for simulated gust loading and programme loading. It was found that, at comparable...