Temperature and strain rate dependent mechanical response of METCO 601 aluminium-polyester abradable seal coating

Abstract

Abradable coatings are utilised as sacrificial materials in low-pressure compressor casings, and in intermediate and high pressure compressors and seals. The adoption of abradable coatings allows for the clearance between compressor blades and casing to be minimised, increasing the overall efficiency of the engine. Quasi-static and dynamic experiments at different temperatures are conducted to characterise the mechanical response of a thermally-sprayed abradable seal coating. The material is composed of an aluminium continuum matrix and fairly well-dispersed polyester particles. Stress versus strain histories are measured in uniaxial tension and compression at strain rates ranging from 10-3 to 102 s-1, via non-standard experimental techniques. The material displays sensitivity to the strain rate and to the imposed temperature. The mechanical behaviour is brittle in tension while it exhibits higher strains to failure in compression. The material is characterised by a pronounced tension/compression asymmetry.

An Inverse Analysis Method for Determining Abradable Constitutive Properties

“…However, typically only the hardness is used to characterise a newly sprayed abradable, leaving open questions about the constitutive behaviour of individual phases and the bulk homogenised properties, and the link between these properties and the behaviour during rub events. Regarding the constitutive properties of AlSi-PES abradables, several investigations have been conducted over a range of strain rates and temperatures through quasi-static compression and Split-Hopkinson Pressure Bar (SHPB) testing [4][5][6]. Chevrier et al [7] then used these results along with complimentary work to fit both a standard and modified Johnson-Cook damage model capable of predicting failure of specimens over a range of temperatures in both quasi-static and dynamic regimes.…”