In order to accurately capture the dynamic characteristics of the actual hard-coating blisk and reduce the computation cost, an equivalent finite element modeling method based on mistuning identification was proposed in this study.
It is shown that the mistuning identification method is effective and feasible, and the identification efficiency is higher than the classical CMM identification method. The mistuning identifications of the numerical case and actual case are carried out respectively, and the identification process of the mistuning identification method in this paper is compared with the one based on the classical CMM model. The input parameters with high amount of data, such as modal shape matrix, are removed from identification formulas, thus, both the amount of data for identification calculation and the workload of vibration testing are reduced. Based on this model, a novel mistuning identification method for the coated blade of the coated blisk by small amount of experimental data is proposed, which can identify the mass, stiffness and damping mistuning of the blade substrates and coatings. In this study, the degrees of freedom of the whole disk of the coated blisk is completely constrained, and the orders of the dynamic model of the coated blisk based on component mode mistuning (CMM) method is further reduced. In particular, the specific influence of the hard-coating damper and the unique strain-dependent manner on the vibration characteristics of the blisk are investigated respectively in terms of the resonant frequencies and corresponding responses.īecause the coatings are likely to produce new mistuning which aggravates the vibration failure of coated blades, it is particularly important to study the mistuning identification for coated blades. An academic blisk deposited NiCoCrAlY + YSZ hard coating is selected as the benchmark case to conduct the nonlinear numerical calculation, and the obtained results are compared with those obtained by the experimental test. An iterative solution procedure based on the Newton–Raphson method is developed to obtain dynamic characteristics of the hard-coating blisk. The dynamic model of the hard-coating blisk is constructed by an analytical energy-based approach. The boundary conditions and continuity conditions of the disk and the hard-coating blades are satisfied by introducing the artificial springs at their interface. Based on the discrete values obtained by the testing, the high-order polynomials are used to characterize the mechanical parameters of the hard-coating damper considering its strain-dependent manner. This paper focuses on the passive vibration reduction of the blisk by the hard-coating damper, and investigates the nonlinear dynamics of the hard-coating blisk. The analysis results indicate that with the increase of coating thickness, the resonance response is reduced significantly and even the thinner coating could also achieve better damping performance. Furthermore, the effects of the coating thickness on the natural frequency and the forced response of an actual blisk are analysed and due to using the same node coordinates, the computational efficiency is improved significantly. By comparing the analysis results obtained by SOLID185 in ANSYS software, experiment and the developed element, this new element is verified that it remains effective for variable coating thickness parameter input. The additional virtual layers to simulate the variations of coating thickness are introduced for the presented element to avoid regenerating new node coordinates.
In this paper, a new laminated element is developed to solve this problem, which needs solely the node coordinates corresponding to the maximum coating thickness. Nevertheless, for the vibration analysis with variable coating thickness by using commercial finite element software, it is necessary to regenerate the finite element mesh, which results in inconvenience in computation. In the damping design of blisks with hard coating, changing coating thickness is one of the frequently used ways for achieving better damping performance.
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