A correction to the analysis of bending under tension tests

The existing analytical solutions for determining an average coefficient of friction in bending under tension tests are revisited. The most commonly used equations are based on the assumption of uniform pressure in the contact interface, which is proven to be a statically inadmissible assumption. New analytical solutions are presented based on the assumption of concentrated forces, which are shown to be statically admissible.

Existing literature supports the existence of localized peaks in the pressure distribution in terms of both numerical simulations and experimental results. Due to the inhomogeneous pressure distribution, bending under tension tests are not considered appropriate for determining the coefficient of friction, but rather a qualitative test capable of relative comparison of tribo-systems.