Study On Performance Of Aero-Engine Thermal Barrier Coating Structure Subjected By Low Speed Impact

Thermal barrier coating is the main thermal protection structure of hot-end parts in aero-engines,it is unavoidably subjected to low-speed impact of particulate during service and maintenance.The damage caused by low-speed impact mostly occurs inside the coating and is not easy to be observed directly from the outside.Therefore,it is important to study damage form caused by low-speed impact on thermal barrier coating.Many advanced thermal barrier coatings are functionally graded structures,from metal adhesive layers to top surface ceramic layer,a gradient laminate structure with gradually decreasing metal material and increasing ceramic material is provided.For ceramics,metals and adhesive materials,the Brittle Cracking criterion,Johnson Cook criterion and Cohesive model are used to describe damage forms of themselves subjected by low-speed impact.Two impact models were established by finite element software ABAQUS,one model contains damage forms of materials and the other model doesn't.In the first model,the change of impact force and deformation on coating affected by different impact modes of rigid ball and mechanical characteristics of coating are discussed.In the second model,the damage forms of ceramics,metals and adhesive materials in coating are summarized.In this paper,an innovative study on the damage characteristics of adhesive layers at different thickness locations was carried out,the influence of different numbers and intervals of rigid balls on damage value and damage distribution of the material are explored.The results show that the impact force and deformation of coating are mainly related to normal kinetic energy of rigid ball.The radius,impact speed and impact angle are factors that directly affect normal kinetic energy;The impact position,gradient index and boundary constraints of coating can all be equivalent factors that indirectly affect normal kinetic energy of rigid ball;Single ball impacts coating,the upper ceramics surface of coating is crushed and broken,the metal material in intermediate gradient layer generates cracks and strain,the failure of adhesive layer results in delamination damage of coating;When multiple balls impact coating,the increasing number of rigid ball leads to an improve of damaged area on coating,the increasing interval reduces the degree of mutual influence between every damages.