| Thermal barrier coatings (TBCs) have been widely used in aircraft turbineengines, due to the remarkable performances of heat protection, abrasion andanti-corrosion. Due to the complex structure and the high temperature environmentfor the thermal barrier coating, so that the bond coating will be oxide occurs betweenthe bond coat layer and the ceramic layer is formed of an oxide layer (Thermallygrown oxide, referred TGO), The main component of the TGO is alumina, its elasticmodulus is larger, leading to higher stress levels than the other three stress levels1to2orders of magnitude, the coating prone to cause stress concentration cracks,expansion and peeling. Therefore, its very important that studying the effect of TGOfor thermal barrier coating life, based on this, the paper analyzes the impact of theturbine blades TGO morphology stress field of thermal barrier coatings using finiteelement method, the main contents in this thesis are listed as follows:Firstly, because of the complicated geometric structure of turbine blade thermalbarrier coating system, rely on the finite element software is difficult to establish itsgeometric model of the actual size, considering TGO morphology further increasedthe difficulty of the geometric model is set up. Therefore, we combined with finiteelement software (ABAQUS) and3D drawing software (CATIA), set up differentTGO morphology of turbine blade finite element geometry model of thermal barriercoating system, the given set material properties, boundary conditions and griddivision, this paper gives the concrete steps in detail.Secondly, for a TGO thickness is10μm, amplitude is20μm model of turbineblade thermal barrier coating. When the thermal barrier coating system with flat platestructure cooling from preparation temperature to room temperature, there are unevenresidual stress in them. And residual compression stress in TGO is estimated-2.5GPa.This layer exist stress singularity which is one of the main reasons cause thermalbarrier coating failure. The calculation of steady temperature field results show thatthe effect of heat insulation of thermal barrier coating is obvious, for the difference intemperature between60%to80%, and the different location of turbine blades that theheat insulation effect is not consistent. Also on the mechanical behavior duringthermal cycling of the finite element simulation, the system layers stress distributionand evolution, the results are in good agreement with the analytic solutions. Thirdly, in this paper, the thermal barrier coating turbine blade system in theprocess of stress fields are simulated, so we can obtain som relative results such as thesystem in the process of thermal cycle about each layer of the3D temperature field,the displacement field and the evolution of stress and strain. Combined with the finiteelement simulation results of various morphologies, and then, comparing the differentTGO morphology model of the stress field levels, analysis of the impact on the TGOmorphology of thermal barrier coating system for turbine blade stress field. Finiteelement simulation results show that under the same TGO thickness, the stress levelsa turbine blade with thermal barrier coating system increases that with increasingthe TGO interface morphology for roughness; Conversely, the roughness interface ofTGO remains constant, When the thickness of TGO increases, the stress is increased.Simultaneously, according to the stress field in the system, we can preliminaryprojections for dangerous area of the ceramic layer.In summary, this paper is based on the finite element method and studying theeffect of stress field which the different TGO morphologies of the turbine blades withthermal barrier coating system, get some meaningful conclusions and provide animportant experimental methods and references, to predict thermal barrier coatingssystem hazardous areas and life prediction theory in the future, but also to expand theapplication fields of the finite element method. |
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