A Predictive Approach to Modelling Frictional Joint Performance (PAMFJP)

The proposed research aims to address the problems inherent in predicting the behaviour of frictional joints. Such joints are an important feature of a wide range of engineering products. Joint behaviour can be beneficial (e.g. by introducing frictional damping and controlling vibration amplitude) or detrimental (e.g. by inducing accelerated wear of fatigue failure). Whilst models now exist for some of these phenomena, it is at present difficult to predict the frictional behaviour of an interface in advance without making experimental measurements under representative conditions. Indeed, uncertainties associated with the behaviour of frictional joints are one of the remaining obstacles to reliable prediction of vibration amplitides and resulting component life.The proposed work addresses the difficulteis outlined above through a combined experimental and modelling programme undertaken by two leading groups in the traditionally separate areas of vibration and structural integrity. The work will be undertaken from a common standpoint and will result in a holistic approach which is valuable to both communities. Intitially, measurements will be made of joint performance using two standard geometries and two material pairs. Measurements will then be taken to characterise the surface topography, material properties, and interface behaviour at microstructural and asperity scales. These measurements will provide input for modelling of the contact, initially at the scale of a single asperity, but later generalised using statistical methods to provide predictions of overall contact behaviour. These predictions will be based on recent developments in the understanding of interface behaviour at the micro- and nano- scales.Finally, validation experiments will be carried out. These will be carefully chosen to give validation of the model in circumstances which differ significantly from the initial characterisation experiments. The overall output of the proposed work will be an enhanced understanding and predictive modelling approach for frictional joints in engineering assemblies such as gas turbine engines. The result will be increased confidence in joint (and therefore overall system) performance, and a reduction in the need for characterisation experiments.