Vibration and flutter analysis of supersonic porous functionally graded material plates with temperature gradient and resting on elastic foundation

Bifurcation and stability analysis of a nonlinear rotor system subjected to constant excitation and rub-impact

Response evaluation of imbalance-rub-pedestal looseness coupling fault on a geometrically nonlinear rotor system

Aero-thermo-elastic flutter analysis of supersonic moderately thick orthotropic plates with general boundary conditions

The rotor–stator rubbing in rotating machinery generated as a consequence of rotor imbalance, shaft misalignment, and casing deformation is a potential threat to the machinery that seriously affects its performance. Timely prediction and correction of the rubbing are essential for the prolonged life of the machinery and its overall performance. A complete understanding of the system behavior during interaction is a great challenge for researchers working in the field of rotor dynamics. Rubbing phenomena involve complex contact nonlinearities and associated thermal effects, which makes the analysis very difficult. Research works in this field are started with the analysis of simple two degree-of-freedom models and now dealing with extensive three-dimensional finite element models. This paper provides a comprehensive review of different numerical models of rotor–stator rubbing with respect to their ability in simulating the actual response characteristics. A detailed description of contact modeling is also presented with the advantages and disadvantages of each model. Different methods for solving the numerical models are briefly explained. In addition, a commentary on different emerging techniques of rub identification is also reported. Finally, some informed recommendations on future directions are made by stating what lacks in the current research activities.

The numerical modeling of rotor–stator rubbing in rotating machinery: a comprehensive review

Aiming at the coupling fault of axial load and radial rub, a geometric nonlinear rotor-casing system is developed in this paper. For the actual case that the aero-engine components (i.e. compressor disc, turbine disc, stator casing, combustor and so on) are sprayed with thermal barrier coatings, the interaction between disc and casing is refined into four stages, including no rub, low rub, rub and high rub. With the increase of invasion depth, the corresponding force models are applied to describe the different impact mechanism. The frictional characteristic between disc and casing is described by the Coulomb model. Then the linear interpolation is used to predict the instantaneous contact of disc-casing and the nonlinear dynamic behaviours of the rotor-casing system subjected to axial load and radial rub are analysed in the form of bifurcation diagram. Moreover, the rub-impact forms, such as full annular rubbing and partial rubbing, are identified by whirl orbit and waveform. On this basis, the dynamic comparison of the rotor system with/without axial load is conducted. The response variations caused by coating hardness and support stiffness of casing are further discussed.

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Dynamics characteristics of a rotor-casing system subjected to axial load and radial rub

The flutter and thermal buckling behavior of laminated composite panels embedded with shape memory alloy (SMA) wires are studied in this research. The classical plate theory and nonlinear von-Karman strain-displacement relation are employed to investigate the aeroelastic behavior of the smart laminated panel. The thermodynamic behaviors of SMA wires are simulated based on one-dimensional Brinson SMA model. The aerodynamic pressure on the panel is described by the nonlinear piston theory. Nonlinear governing partial differential equations of motion are derived for the panel via the Hamilton principle. The effects of ply angle of the composite panel, SMA layer location and orientation, SMA wires temperature, volume fraction and prestrain on the buckling, flutter boundary, and amplitude of limit cycle oscillation of the panel are analyzed in detail.

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Flutter and Thermal Buckling Analysis for Composite Laminated Panel Embedded with Shape Memory Alloy Wires in Supersonic Flow

Taking into account surface coatings painted on disc and casing, a nonlinear rotor system is established for simulating unbalance-rubbing coupled fault. During the modeling process of shaft, the nonlinear geometric relation between displacement and strain is considered. According to the Hamilton's principle, the restoring force between disc and shaft is described by the equivalent spring and the equivalent damper, and then the equivalent dynamic model is further set up. For contact analysis, the novel contact force model is employed to describe the impact force between disc and casing. Meanwhile, the Coulomb model is used to simulate the frictional force. The motion equations of the equivalent dynamic model are solved numerically and the corresponding dynamic behaviors are analyzed by bifurcation diagram, whirl orbit and Poincare map. The relationship between equivalent linear/nonlinear stiffness and structural parameters is analyzed in detail. Moreover, the effects of eccentricity of disc, surface coatings and radius of shaft on the dynamic characteristic of the equivalent model are discussed.

Rubbing analysis of a nonlinear rotor system with surface coatings

The novelty of this study is to present a theoretical approach to investigate the dynamic behaviors of the laminated panels under arbitrary elastic boundary conditions. The motion equations of pane...

Vibration characteristics and thermoelastic analysis of the supersonic composite laminated panel with arbitrary elastic boundaries

The ONERA aerodynamic model is a nonlinear aerodynamic model which includes the effects of dynamic stall. With the strip theory, the ONERA model is usually used in the aeroelastic analysis of slender wings. To the classical approach for the ONERA model, the circulatory and nonlinear parts are all described by using aerodynamic elements and the simulation cost may be very high. In this paper, an alternative simulation approach is proposed to simplify the calculations for the ONERA model, in which the circulatory part of the ONERA model is solved analytically by using Duhamel integral method. In this way, the corresponding aerodynamic loads can be directly expressed in the modal space of the wing motion through only introducing two additional variables. For a slender wing model, the new simulation approach is used to analyze its nonlinear aeroelastic responses. In the simulation, the number of the state variables for the system using the proposed approach is reduced modestly comparing with that using the classical approach. In addition, for a slender wing with a pylon-store system which includes a free-play gap, both the proposed approach and the classical approach with the same number of aerodynamic elements are used to analyze the nonlinear dynamic behaviors of the system. Simulation results are given to show that the pylon-store system with a free-play gap can lead the occurrence of sub-critical Hopf bifurcation for a slender wing. Additionally, some nonlinear dynamic phenomena about the wing-pylon-store system are observed by using the new approach. But these phenomena cannot be predicted by employing the classical approach with the same number of aerodynamic elements used in the new approach. The peak of the post-critical responses obtained from the classical approach are larger than those obtained from the new approach in most range of free-stream velocity. The nonlinear flutter velocity predicted by using the classical approach is lower than that predicted by using the new approach.

An alternative simulation approach for the ONERA aerodynamic model and its application in the nonlinear aeroelastic analysis of slender wings with pylon-store system

Yuqian Xu

Papers

Dynamics characteristics of a rotor-casing system subjected to axial load and radial rub

Flutter and Thermal Buckling Analysis for Composite Laminated Panel Embedded with Shape Memory Alloy Wires in Supersonic Flow

Rubbing analysis of a nonlinear rotor system with surface coatings

Vibration characteristics and thermoelastic analysis of the supersonic composite laminated panel with arbitrary elastic boundaries

An alternative simulation approach for the ONERA aerodynamic model and its application in the nonlinear aeroelastic analysis of slender wings with pylon-store system