Computational Contact Modelling of Hip Resurfacing Devices
A combination of computational models and theoretical methods have been used and developed to study the contact of hip resurfacing devices under normal and edge loading conditions. Techniques were developed and the solutions based on using the finite elem
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Abstract A combination of computational models and theoretical methods have been used and developed to study the contact of hip resurfacing devices under normal and edge loading conditions. Techniques were developed and the solutions based on using the finite element method. It was found that the study of hip joint modelling, numerical methodologies of mechanical wear simulations and shakedown analysis can be developed to study the contact mechanics and biotribology of hip resurfacing devices under central and edge loading conditions. Each method developed in this study provides a unique platform to study these problems. Keywords Biotribology Shakedown · Wear
· Contact · Finite element analysis · Microseperation ·
1 Introduction Contact mechanics, wear and surface damage of hip resurfacing devices are subjects which have been studied since very early implantations and the longevity of the devices are becoming increasingly important. The wear and surface damage of these bearing surfaces occur through normal gait loading conditions, however, another problem is the stripe wear patterns observed on metal-on-metal patient retrievals [1] and assessed devices following hip simulator studies [2]. It has been claimed that edge loading occurs during the walking cycle of the patient; therefore ‘microseperation’ is simulated into each cycle during experimental wear testing [3]. The laxity of the hip joint is understood to lead to microseperation during the gait M. Ali (B) · K. Mao School of Engineering, University of Warwick, Coventry CV4 7AL, UK e-mail: [email protected] K. Mao e-mail: [email protected] G.-C. Yang et al. (eds.), IAENG Transactions on Engineering Technologies, Lecture Notes in Electrical Engineering 229, DOI: 10.1007/978-94-007-6190-2_14, © Springer Science+Business Media Dordrecht 2013
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172 Femoral head component (normal loading)
M. Ali and K. Mao Femoral head component (edge loading)
Acetabular component (normal loading)
Acetabular component (edge loading)
Fig. 1 Hip resurfacing device with normal and edge loading wear patterns
cycle, and fluoroscopy studies have revealed how edge loading of the hip joint occurs due to lateral sliding of the femoral component during gait [3]. The differences between wear patterns observed during normal and edge loading conditions is shown schematically in Fig. 1. This study expands on the research conducted by Ali and Mao [4] to further develop techniques in assessing both the contact mechanics for wear modelling and the application shakedown theory to cyclically loaded hip resurfacing devices, particularly those under normal and microseperation conditions leading to edge loaded hip resurfaced bearings.
2 Contact, Wear and Shakedown Theory Contact mechanics forms an integral part to predicting the contact stresses and mechanical wear associated with hip resurfacing devices. For studying the wear of orthopaedic devices, the Archard wear model [5] has been used with finite element analysis techniques. Although the Archard wear model [6] appears in many fo
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