Abstract
Local sensitivity analysis, which describes the relative importance of specific design parameters to the response of systems, is crucial for investigating dominant factors in optimal design. In this paper, local sensitivity analysis of the response of rotors with rub-impact to parameters of rubbing interfaces is carried out. The steady-state motion of the rotor is evaluated by a harmonic balance method and the sensitivity coefficients for every rotation speed over the speed range are derived analytically. Two classical models, including the Duffing oscillator and the gap model, are utilized to validate the accuracy and capability of the adopted methods and high accuracy is shown. Numerical investigations of sensitivities of steady-state response of rotors to parameters of rubbing interfaces are then carried out, based on a lumped Jeffcott rotor and a finite element model respectively. Conclusions are drawn that the response of rotors subjected to rubbing problems is more sensitive to initial clearance than other parameters of the applied friction model. With increase of initial gap, the response of rotors becomes more sensitive and the range of region subjected to rub-impact forces shrinks until the separation of rotor and stator.
Highlights
For the purpose of searching for optimal design parameters for rotating machinery, investigations of the dynamic characteristics of the system, such as stability analysis [1,2], reliability analysis [3] and optimal design analysis [4] based on specific criteria, have been performed by many scholars
Sensitivity analysis can provide quantitative information about to what extent does the responses of rotating system change when the design parameters varies from a base case, dominant impact factors can be found based on a restricted number of cases rather than enormous amount of data
Melchers and Ahammed [8] presented a structural sensitivity analysis approach based on moment and compared the results with those computed by a conventional Monte Carlo method
Summary
For the purpose of searching for optimal design parameters for rotating machinery, investigations of the dynamic characteristics of the system, such as stability analysis [1,2], reliability analysis [3] and optimal design analysis [4] based on specific criteria, have been performed by many scholars. A sensitivity analysis is suggested when researching the dynamic characteristics of a system. Su [7] et al proposed a method to assess the extent of rotor failure and investigated the frequency reliability sensitivity with respect to several stochastic parameters. Melchers and Ahammed [8] presented a structural sensitivity analysis approach based on moment and compared the results with those computed by a conventional Monte Carlo method. Leister [12] et al proposed a new sensitivity analysis method for a rotor supported by two bearings. Pan [14] et al applied sensitivity analysis to investigate the influence of the mass and the offset of disk on rotors. Based on the model they proposed, the influence of load variation on dynamic characteristics and sensitivities of a multi-support structure is researched. Anusonti-Inthra [17] et al carried out sensitivity analysis and uncertainty qualification for a coaxial rotor system, where the sensitivities of hub loads with respect to ambient drift speed, rotor angular speed and center of gravity location on the blade are investigated
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