Vibration Characteristics Analysis And Damping Optimization Of Partially-covered Hard-Coating Thin Plate Structures

The hard-coating technology is a new vibration reduction measure for the thin-walled components of the power equipment,which is suitable for the working condition of power equipment and can suppress harmful vibration effectively.The hard coating can effectively control the excessive vibration of thin shell structure under high temperature and high corrosive environment.However,because most structures are not allowed to significantly increase or change its mass,volume and natural frequency in the process of vibration reduction,thus,the hard coating can only be deposited on a part of the surface of the thin shell structure.In this paper,thin plate which can effectively simulate thin-walled components of power equipments is selected as the research object.In order to obtain the best coating position on the thin plate structure,the modified modal strain energy method and multiple population genetic algorithm have been developed to solve the damping optimization problem of the hard coating composite structure.The specific research content is divided into the following five parts:(1)The finite element equation of motion of the partially-covered hard-coating thin plate is established by using four node plate element.Then,the formula for calculating the modal loss factor of the hard-coating thin plate is determined by using the modified modal strain energy method,and the solution method of vibration response of the hard-coating composite structure under base excitation is given.Finally,a cantilever plate partially deposited with NiCoCrAlY+YSZ material is taken as an example to carry out a case study.Based on the developed method and ANSYS software,the inherent characteristics and frequency response of the partially-covered hard-coating thin plate are solved.(2)The analytical model of the partially-covered hard-coating thin plate is established by using the classical thin plate theory.First,the displacement field of the partially-covered hard-coating thin plate is characterized by orthogonal polynomials.Based on the energy method and Lagrange equation,the free equation of motion and the forced vibration equation under the base excitation are derived,and the method to solve its inherent characteristics and vibration response is given.Finally,a cantilever plate partially deposited with NiCoCrAlY+YSZ material is taken as an example to carry out a case study.The free vibration and forced vibration of the partially-covered hard-coating thin plate are analyzed by the developed analytical model,and the results are compared with those of the ANSYS analysis and the experiment to prove the rationality of the developed model.(3)Based on the developed finite element model of the partially-covered hard-coating composite structure,the location,parameters,area and shape of the coating are selected as the research variables,and the reasonable range is determined.The inherent characteristics and resonance response of the corresponding structure are solved by self-made Matlab program,and the influence of the above variables on the vibration characteristics of the thin plate is expressed in the form of table and drawing.The results show that the damping capacity of the hard-coating composite structure can be improved by increasing the parameters and area of hard coating material,and the change of the coating position and shape has a certain influence on the damping capacity of the coating composite structure.(4)In order to obtain the maximum modal loss factor of the composite structure,the damping optimization model of hard-coating thin plate is given with the coating location as the design variable,and the method of solving the optimization problem by using multiple population genetic algorithm is described.Then,based on the developed optimization model and optimization method,the optimization of the coating location is carried out on the plate,and the rationality of the optimization results is verified by the experiment.The results indicate that on the premise of fixed coating area,the optimization of the targeted order can reasonably determine the coating location in order to make the damping performance of the whole composite plate optimum.(5)The optimization model of the partially-covered hard-coating composite structure was established with the coating location as the design variable,and the reciprocal maximization of the resonance response peak(i.e.the minimum resonance response peak value)and the non-resonance frequency response minimization on the specified position of the composite structure under base excitation as the optimization objective.Moreover,a multiple population genetic algorithm is proposed to solve the optimization problem.Finally,a cantilever plate partially deposited with NiCoCrAlY+YSZ material is taken as an example to carry out a case study.Based on the developed optimization model and optimization method,the optimization of the coating location is carried out on the plateThe research results of this paper can provide reference for the study of the vibration characteristics of the partially-covered hard-coating composite structures,and also provide support for the optimization design of hard-coating composite structures.