Effect of sliding friction on spline surface failure under misaligned condition in aero engines

The misaligned condition in splines coupling brings more relative motion between the engaging tooth surface and subsequently a rise of wear phenomenon. The sliding friction between the spline surfaces and initial gap between the teeth are the key roles in wear behaviour in both crowned and straight splines. The paper aims to discuss these issues.

There is a design constraint to include fretting and wear damage of spline surface in design criteria. It becomes very essential to use a finite element tool to evaluate the wear behaviour of spline surface in order to design for severe environmental conditions. The fretting fatigue and fretting wear damage mechanisms on the spline surfaces are mainly dependent on the forces between the spline surfaces and relative movement between the teeth. This study focusses on the effect of sliding friction coefficients on the wear damage of the spline surfaces based on mating condition.

Analysis shows that the contact pressure and root stress increase with increasing friction coefficient and misalignment. This is irrelevant to the crowned type of splines. This case becomes worst when the spline has more misaligned condition.

The fretting wear damage of straight spline is essential criterial for the application in aero engines and the crowned spline under controlled misaligned condition provides better wear life compared to straight spline surfaces.