Papers by Author: Edward J. Williams

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Authors: Edward J. Williams, Arcangelo Messina
Authors: Ran Li, W. Sun, Thomas H. Hyde, Edward J. Williams, Xing Guo Wang
Abstract: A fatigue crack growth test program has been carried out on hollow, SuperCMV shaft specimens, with transverse holes, under combined torsional and axial loading. The experimental results show that fatigue cracks always initiated in the stress concentration areas, i.e., in the transverse holes. Up to four cracks were observed to be initiated at different positions near the holes in the shafts. The fatigue crack propagation was initially found to occur under Mode I conditions, followed by a period of mixed Mode II/III crack growth. Three dimensional, finite element, elastic-plastic analyses have also been conducted, in an attempt to predict the crack-initiation locations and lives. The predicted crack-initiation sites agree with the experimental observations, for a range of loading conditions. The initiation sites were found to be approximately on the planes of maximum principal stress. The predicted, torque-dominated, fatigue lives of the shafts, obtained by use of a stress-life (S-N) approach, correlate reasonably well with the experimental results.
Authors: William S. Robotham, Thomas H. Hyde, Edward J. Williams
Authors: D. Houghton, P.M. Wavish, Edward J. Williams, Sean B. Leen
Abstract: This paper investigates the comparison of the measured and predicted force-displacement loops of a multiaxial representative fretting fatigue test rig for aeroengine spline couplings. A local finite element model of the fretting specimen and the fretting bridge is outlined. A more extensive model of the fretting test rig is then introduced. This global model also includes the loading structures. The model captures the compliance of the fretting test rig and improves the correlation of the observed hysteresis. This method allows the slip amplitude at the contacts to be quantified.
Authors: William S. Robotham, Thomas H. Hyde, Edward J. Williams, Paul Brown, Ian R. McColl, C.J. Kong
Abstract: The development of aeroengines with increasing thrust capabilities requires the development of shaft technology to deal with this greater power transmission, whilst still restricting their dimensions and weight. Modern aerospace drive shafts are predominantly of a single-alloy design and significant benefits could be obtained from using a dual alloy shaft, where a high temperature alloy is used at the turbine, i.e. hot, end of the shaft and a high strength alloy is used for the spline end of the shaft, where high strength is required, rather than high temperature performance. Whilst the processes of joining dissimilar materials are widely used the evolution of the joint and its strength characteristics are not fully understood. A program of research has been instigated to lead to an improved understanding of friction welds and their behaviour under monotonic and cyclic loadings with the overall objective to establish confidence in the welding parameters for these material combinations and the associated post-weld heat treatments. This paper presents an overview of the mechanical testing program and the aims of this work, illustrated with some examples from the monotonic and cyclic test work carried out on inertia friction welded dual alloy shaft components.
Authors: Wei Siang Sum, Sean B. Leen, Edward J. Williams
Authors: Jian Ding, J. Madge, Sean B. Leen, Edward J. Williams
Abstract: The prediction of fretting wear and fretting fatigue is a significant issue for the design of high-performance aeroengine spline couplings, due to the potential for slip between the highlyloaded spline teeth under cyclic loads. The work reported here builds on previous work on simpler (Hertzian) laboratory test configurations to take a step towards a unified fretting wear and fatigue modelling approach, which considers the evolution of contact geometry with material removal and consequently the changes in fatigue-pertinent subsurface stresses. The approach calculates the local wear, that it is the wear at each contact node, as a function of local contact pressure and local slip. The influence of wear damage on fretting fatigue behaviour is quantitatively assessed by computing the change of a shear strain based fatigue damage parameter, i.e. the critical-plane Fatemi-Socie parameter. The application of the simulation tool to the complex geometry of a helical spline coupling is discussed.
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