A comparative and comprehensive study on the friction coefficient in simulations for NITINOL medical device life cycle loading scenarios.

Numerical simulations are a substantial element, not only in the design process of high-risk medical devices, but also for designing the manufacturing process for these products. No matter whether evaluating heart valves under fatigue loading, or stents subjected to radial compression during the device loading procedure, they have one crucial interaction mechanism in common. At least two surfaces, commonly of different materials, are in mutual contact and are subjected to relative motion. In the majority of corresponding numerical simulations, the often neglected or at least underestimated role of frictional interactions are one root cause of discrepancies to experimental results or the deformation behavior compared to in-situ loadings.

In this study this essential effect is addressed and studied in carefully defined numerical simulations and tribological tests. Despite the well-known sensitivity of the friction coefficient to variances in surface roughness, temperature or material properties, the studied materials were derived from process relevant material combinations. The objective of this work is to show the influence of friction on the deformation behavior during different loading scenarios in finite element simulations of high-risk medical devices. In conclusion, the experimental findings of this work are discussed with respect to common literature and extended by a comprehensive overview of friction coefficients for medical device surface interactions.