Contact Mechanics and Material Removal in Abradable Linings

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Abradable linings are used within compressors and turbines as they allow blade tip clearances to be minimised, whilst not suffering the penalty of blade tip wear. They are of particular interest in aero-engines, where they help to improve engine efficiency and minimise the consumption of aviation fuel. This proposal is concerned with investigating cutting type wear experienced by abradable linings, during the incursion of a blade tip into the lining. Previous studies have considered the process to be similar to that of high speed machining, whereas recent observations from engine tests have indicated that debris is in fact ejected from the rear of the contact.In this study a demonstrator platform will be developed for simulating aero-engine compressor rubs, and the associated contact mechanics investigated using an ultrasonic technique in combination with a finite element model. Through this approach, material failure points will be identified, and insight gained as to why debris is ejected from the rear of the contact. Blade tip geometries will also be investigated as part of this study, as well as their effect on material removal. This topic area is particularly pertinent as aero-engine manufacturer's looks to minimise blade tip clearances further inorder to increase engine efficiency, thus increasing the frequency of abrasion events.