Prediction And Optimizing Of Damping Characteristics Of Hard-coating Thin Plate By The Modified Modal Strain Energy Method

Hard coating is the coating material that is made of metal, ceramic or the mixture of both. In recent years, the study found that the damping coefficient of the composite structure coated with hard coating increases and the resonance stress reduces. The hard coating has the effect of damping vibration attenuation. The key content of the research of hard coating damping vibration attenuation is the prediction of damping characteristics of hard coating composite structure. The modal strain energy method is a classic method to predict damping of the composite structure. But the classic modal strain energy method can’t be directly applied to the prediction of damping of hard coating composite structure. On the basis of considering the small damping characteristics of hard coating materials and modifying the calculation error caused by the classic modal strain energy method, a new method was proposed in this paper and applied to the prediction of damping of hard coating composite structure. The optimization design research of the coating position was carried out. The concrete research content is embodied in the following four aspects.Firstly, the basic theory of modal strain energy method was elaborated. The theoretical formulas of solving overall modal strain energy and element modal strain energy were provided. The cantilever titanium plate was regarded as an instance to demonstrate the proposed formulas. The natural frequency, the overall modal strain energy and the distribution of element modal strain energy of the first six order modes of the clamped thin plate structure were calculated in ANSYS and Matlab. The specific processes and main orders of relevant calculation were narrated. The calculation results were compared.Secondly, the process of the prediction of damping of hard coating composite structure applying classical modal strain energy method was introduced. On the basis of improving the calculation error caused by the classic modal strain energy method, two modified modal strain energy method was proposed and applied to the prediction of damping of hard coating composite structure. The principle formulas of modified modal strain energy method were deduced. The calculation procedure of the prediction of damping was described. The cantilever plate coated with Mg-AL hard coating was regarded as an instance to demonstrate the proposed method.Thirdly, The effects of Young’s modulus, loss factor of hard coating materials and coating thickness on damping characteristics of hard coating composite structure were also discussed in this study. The influence regulations of the single factor and the combination of two factors on the damping characteristics were explored respectively. The results showed that the damping properties of composite structure can be improved by increasing the Young’s modulus of hard coatings, loss factor and the thickness.Eventually, the damping optimization design of the partial coating position on hard coating composite structure was accomplished. The placement strategies of hard coating patches are devised using the modal strain energy method. The damping effects for partially covered hard coating thin plate to damp the single mode or a set of modes of vibrations were investigated separately. The effect of the area of hard coating patch on damping characteristics of composite structure was also discussed. Extensive experiments were conducted by making number of separate samples of hard coating layer damping patches for each configuration to damp different modes simultaneously or independently. The experimental results demonstrate utility of the modal strain energy technique as an effective tool for selecting the locations of the hard coating damping treatment to achieve desired damping characteristics over a broad frequency band.The relevant research results can be used as a reference for the preparation of hard coating materials and design of damping vibration reduction, and can also support the application of hard coating damping technology in dynamics equipment thin shell structures.