Papers by Author: 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.

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.

Abstract: This paper describes the conceptual, embodiment and detailed design of a representative test specimen to mimic fretting variables in aero-engine splined couplings. A fretting bridge design was chosen for the multi-axial representative specimen from a set of four concepts evaluated. The test specimen was intended to facilitate more rapid testing for design against fretting fatigue and wear in the complex contact geometry of the spline coupling.

Abstract: This paper reviews a range of simplified and approximate techniques developed and implemented by the authors in the context of elastic-plastic, elastic-creep and elastic-plastic-creep, monotonic loading of both simple components and complex structures. The primary motivation for the work is to provide more rapid methods for estimating failure variables for damage assessment of structures. The context of the work has included both aerospace structures and tubular frameworks, such as offshore jacket-type structures, both of which belong to a class of structures, which contain repeated units where localised plastic damage may be concentrated.