Modeling Deformation and Failure in Alsi-Polyester Abradable Sealcoating Material Using Microstructure-Based Finite Element Simulation

Abstract

A plasma-sprayed aluminum-silicon (AlSi)/polyester coating is applied in gas turbine engines as an abradable sealcoating to maintain tight clearances between rotating blades and static casing. While running the engine, the rotating blades “rub” with the abradable coating, resulting in extreme strain rate (up to 106) dynamics and a high-temperature environment. Due to the difficulty of direct-collecting measurements, predictive computational models are important for analyzing deformation and failure of abradable material, to help meet the design target of avoiding damage to the blade tip and maintaining high-fuel-efficiency. In this research, a microstructure-based finite element  computational model was developed to capture the complex mechanical behavior of the abradable material. The model is based on a virtual representative-volume-element (RVE) of a metal-polymer microstructure, reconstructed from x-ray computed tomography. It models the plastic deformation and damage in each AlSi and  polyester constituents, and failure at their interface. The model was calibrated and validated with uniaxial tension and compression experiments, with further study on  influence of varying microstructure. The material exhibited strongly tension-compression asymmetry and  sensitivity to temperature, which was well-captured by model.  The model is expected to facilitate the development of improved abradable materials by bypassing the conventional trial-and-error approach and extensive testing requirements.

Keywords: abradable material, AlSi/polyester microstructure, finite element modeling, Failure mechanism