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The popularity of minimally invasive surgical procedures is driving the development of novel, safer and more accurate surgical tools. In this context a multi-part probe for soft tissue surgery is being developed in the Mechatronics in Medicine Laboratory at Imperial College, London. This study reports an optimization procedure using finite element methods, for the identification of an interlock geometry able to limit the separation of the segments composing the multi-part probe. An optimal geometry was obtained and the corresponding three-dimensional finite element model validated experimentally. Simulation results are shown to be consistent with the physical experiments. The outcome of this study is an important step in the provision of a novel miniature steerable probe for surgery.

The development of a quadratic programming formulation for the solution of layered elastic contact problems in the presence of friction is presented in this paper. Conveyor belts, tyred wheels, composite cylinders, and conrod bearings, are classical examples of systems which can be studied using the efficient numerical methodology proposed here. In this type of mechanical assembly, micro-slip between the mating surfaces often occurs and may eventually lead to system failure. Accurately capturing the evolution of slip and stick areas using a computationally inexpensive procedure (as an alternative to full finite element analysis) is therefore key to preventing these failures and to improving the design of various engineering components. The proposed approach is first tested and validated against classical marching-in-time solutions for two-dimensional layered systems in the presence of both static and moving loads. Results are then extended to demonstrate the feasibility of the technique to study systems with multiple slip regions and to solve rolling contact problems of practical interest. Finally, the numerical methodology is successfully applied to the prediction of frictional creep of tyred cylinders. Experimental corroboration has been obtained by testing tyred discs.

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