Dynamic Investigation And Multi-Parameter Constrained Optimization Design Of The Blisk(Integrally Bladed Disk) Deposited Hard Coating On The Blades

The blisk was manufactured as one-piece structure either by welding blades on rotors or by machining entire bladed disks from single pieces of metal.As a result,it does not benefit from the vibration damping provided by dovetail attachments,which can lead to the fatigue failures in harsh conditions.Moreover,the stiffness of the blade and disk are close due to thin disk,which may cause coupling resonance of the blisk.In addition,the vibration suppression and damage healing of the blisk are difficult because of the unique one-piece structure.Recent researches revealed that the hard coating prepared by the metals,ceramics and their mixture has the superior damping capacities,and can be employed as a novel technology for damping improvement.On the basis of the dynamic modelling and coupling vibration analysis of the blisk,the dynamic modelling and vibration characteristics of the blisk deposited hard coating on the blades(hard-coating blisk)were investigated using the semi-analytical method,finite element method and experimental test,and then the multi-parameter constrained optimization design of hard coating were conduct in this project.The main contents of this project can be summarized briefly as below:Firstly,the semi-analytical model(SAM)of tuned blisk and the finite element reduced-order model(FEROM)of mistuned blisk were established respectively using the energy-based Ritz method and modified fixed-interface component mode synthesis(CMS)method,then the modal characteristics and vibration responses of the blisk were calculated,which were compared with the experimental results for model validation.The influences of structural parameters and the mistuning manner of blisk on its coupling vibration was investigated by the above-mentioned SAM and FEROM,respectively.Secondly,considering the mechanical properties of NiCoCrAl+YSZ hard coating,the SAM of the hard-coating tuned blisk was constructed by the complex modulus,composite Oberst plate theory and Rayleigh-Ritz method,the FEROM of the hard-coating mistuned blisk was established by the circular symmetry of tuned system,the SNM method based on the criterion of closely spaced modes,modal strain energy method and Rayleigh damping,then the modal characteristics and vibration responses of the hard-coating blisk were solved,and compared with experimental results for model validation.Subsequently,the mechanism of hard coating for vibration suppression of the blisk was analyzed,and the influences of the thickness and elastic modulus of hard coating on the dynamics of blisk were analyzed,moreover,the effect of the bladed aspect ratio and the disk thickness influencing the coupling vibration greatly on the vibration suppression of the blisk by hard coating were also studied,respectively.Thirdly,in consideration of the strain-dependent manner of NiCoCrAl+YSZ hard coating,the strain-dependent elastic modulus of loss factor were characterized by modified complex modulus,higher-order polynomial and experiment results,and the nonlinear SAM of the tuned blisk deposited strain-dependent hard coating was built using the complex Oberst plate theory and Rayleigh-Ritz method,by proposed iterative solution based on Newton-Raphson method,the nonlinear resonant frequencies and responses were obtained,and compared with those obtained by the experimental test for model validation.Moreover,the damping performance of hard coating for vibration suppression of tuned blisk was studied.The specific influences of strain-dependent manner on the mechanical parameters and vibration characteristics of the hard coating and the blade and the tuned blisk were also investigated.Finally,using the strain-dependent complex modulus and composite Mindlin plate theory,the nonlinear FEM of the tuned blisk deposited hard coating was gotten,and another iterative solution-based on the Newton-Raphson method was developed to solve the nonlinear resonant frequencies and responses,and compared with those of experimental results to validate the nonlinear FEM.Then,the multi-parameter constrained optimization design of hard-coating tuned blisk was conducted by the nonlinear FEM and reference point based NSGA-II(non-dominated sorting genetic algorithm II).In which,the initial elastic modulus,initial loss factor and thickness of hard coating are taken as the design variables,and maximization of modal loss factors,the minimization of frequencies variations and the minimization mass gain of tuned blisk were considered as the objective functions.The obtained results of bi-objective and triple-objective optimizations were expressed as the curved line and frontier surface of the Pareto front,respectively.In addition,the vibration responses were also achieved to verify the obtained constrained optimal solutions.The dynamic modelling and coupling vibration of the blisk were investigated considering its structural feature,and an innovative way for damping vibration suppression of the blisk by hard coating was proposed,and the novel methods for solving the linear and strain-dependent dynamics of hard-coating blisk were developed here.Specifically,the influence of hard coating on the vibration suppression of the blisk was investigated,the influences of coating parameters on the dynamics of the blisk were analyzed,and the effect of structural parameters influencing coupling vibration of the blisk on the performance of vibration suppression of hard coating were also studied.Moreover,the multi-parameter constrained optimization design of the hard coating in the hard-coating blisk was conducted to promote the flexible application of the damping vibration suppression of hard coating on the blisk.The obtained results can give the researchers useful guidance with respect to the dynamic design of the blisk and the application of hard coating on vibration suppression.