Rain Erosion: From Multi-physics Modelling to Efficient and Cost-effective Qualification

Abstract

This thesis explores the structural implications of the rain erosion of thin film coatings onexterior aircraft surfaces through the lenses of testing and finite element modelling (FEM). Currently, there is no accurate method to model the erosion of exterior aircraft surfaces by rain during flight. The primary objective of this research project is to develop novel experimental and simulation techniques to predict the rain erosion degradation of coatings used by the aerospace industry. With the use of FEM, physical testing can be limited; thereby lowering costs, reducing time to market, and streamlining the qualification process. This study began by recreating an analysis performed on the modelling of rain erosion on the leading edge of a wind turbine blade. This approach models a rain droplet with smooth particle hyrdo-dynamics (SPH) and has been successfully recreated. For the rain erosion of aircraft, computational fluid dynamics (CFD) was utilized to determine the stresses resulting from a rain droplet impact in lieu of SPH. Thin film materials were characterized through tensile and nanoindentation testing in order to model materials’ elasto-viscoplastic properties for the finite element model. Nanoindentation testing allows for the direct extraction of a compressive reduced modulus and iteration techniques may be used to determine the plastic behaviour of each material. Interfacial property characterization is in progress which will aid in future crack propagation studies. Finally, the results from CFD simulations can be combined with material profiles and interfacial characteristics in order to model rain erosion across aircraft exteriors. The tensile models have been successfully calibrated for all materials and the nanoindentaion modelling, although still in progress, is showing correlation for the materials that have been modelled thus far. Preliminary rain erosion simulations include a full 3D, elastoviscoplastic flat plate model showing promising results matching the expected material response.