Houghton, Dean (2009) Representative fretting fatigue testing and prediction for splined couplings. PhD thesis, University of Nottingham.
Spline couplings are a compact and efficient means for transferring torque between shafts in gas turbine aeroengines. With competition in the aerospace market and the need to reduce fuel burn from the flight carriers, there is an ever-present requirement for enhanced performance. Spline couplings are complex components that can fail from a variety of mechanisms, and are susceptible to fretting wear and fretting fatigue (FF). Due to the expensive nature of full-scale testing, this thesis investigates the use of the representative specimen (RS) concept for predicting fretting-induced damage between spline teeth.
A combined experimental and computational RS methodology is developed, using a uniaxial representative specimen (URS) and a multiaxial representative specimen (MRS). The URS test rig simulates spline torque and axial loads from the overall flight cycle and associated damage. The MRS simulates the combination of the same major loads, with the addition of high-cycle bending loads from in-flight fluctuations. The URS was successfully employed for experimental characterisation of a range of spline material combinations, including inference of the coefficient-of-friction. The MRS successfully characterised the multiaxial FF behaviour of the current material of choice for triple-spool gas turbine couplings.
A finite element-based total fatigue life (crack nucleation and propagation) capability was successfully validated for the MRS and URS. A global sub-modelling technique was employed, whereby a critical-plane Smith-Watson-Topper (SWT) fatigue parameter predicted crack nucleation, an El Haddad approach predicted short crack growth and a weighted function approach predicted long crack growth. A novel FF damage parameter, Dfret, was also implemented to incorporate the combined effects of relative slip and surface shear traction, in conjunction with the SWT parameter, for life prediction. The required material constants were obtained and captured the measured effect of relative slip on a titanium alloy and the measured effect of contact size on an aluminium alloy.
|Item Type:||Thesis (PhD)|
|Uncontrolled Keywords:||Fretting fatigue|
|Faculties/Schools:||UK Campuses > Faculty of Engineering > Department of Mechanical, Materials and Manufacturing Engineering|
|Deposited By:||Mr Dean Houghton|
|Deposited On:||13 May 2010 14:54|
|Last Modified:||15 Feb 2011 10:41|
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