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Deyou Wang - One of the best experts on this subject based on the ideXlab platform.
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research on vibration performance of the nonlinear combined support flexible Rotor System
Nonlinear Dynamics, 2019Co-Authors: Zhong Luo, Jinwen Wang, Rui Tang, Deyou WangAbstract:A finite element model of the cantilever combined support Rotor included two discs established in this paper to predict and explain the nonlinear vibration phenomenon. The model considered local nonlinear support force generated by the combined support and the coupling effects of the Rotor with the combined support. The nonlinear factors contained the clearance, the Hertz contact force and the vibration of the rolling bearing and the nonlinear force of the squeeze film damper. The combined support included bearing, squeeze film damper and squirrel cage elastic support. Finally, the high-dimensional partial differential equations with local nonlinearity were derived and solved by Newmark- $$\upbeta $$ combined with Runge–Kutta method. Based on the above theoretical results, the bifurcation phenomenon of vibration response at different positions was analysed and the dynamic response of the Rotor System at different positions due to the rotational speed was compared.
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response analysis of a dual disc Rotor System with multi unbalances multi fixed point rubbing faults
Nonlinear Dynamics, 2017Co-Authors: Yang Yang, Deyou Wang, Dengqing Cao, Guangyi JiangAbstract:Rotor unbalance and rub-impact are major concerns in rotating machinery. In order to study the dynamic characteristics of these machinery faults, a dual-disc Rotor System capable of describing the mechanical vibration resulting from multi-unbalances and multi-fixed-point rub-impact faults is formulated using Euler beam element. The Lankarani–Nikravesh model is used to describe the nonlinear impact forces between discs and casing convex points, and the Coulomb model is applied to simulate the frictional characteristics. To predict the moment of rub-impact happening, a linear interpolation method is carried out in the numerical simulation. The coupling equations are numerically solved using a combination of the linear interpolation method and the Runge–Kutta method. Then, the dynamic behaviours of the Rotor System are analysed by the bifurcation diagram, whirl orbit, Poincare map and spectrum plot. The effects of rotating speed, phase difference of unbalances, convex point of casing and initial clearance on the responses are investigated in detail. The numerical results reveal that a variety of motion types are found, such as periodic, multi-periodic and quasi-periodic motions. Moreover, the energy transfer between the compressor disc and the turbine disc occurs in the multi-fixed-point rubbing faults. Compared with the parameters of the turbine disc, those of the compressor disc can affect the motion of the Rotor System more significantly. That is, the responses exhibit simple 1T-periodic motion in the wide range of rotating speed under the conditions of sharp convex point and larger initial clearance. These forms of dynamic characteristics can be effectively used to diagnose the fixed-point rub-impact faults.
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prediction of dynamic characteristics of a dual Rotor System with fixed point rubbing theoretical analysis and experimental study
International Journal of Mechanical Sciences, 2016Co-Authors: Yang Yang, Dengqing Cao, Deyou WangAbstract:Abstract For theoretical and experimental research on the fixed point rubbing of aero-engine, a dual-Rotor System capable of describing the mechanical vibration resulting from two imbalances and fixed point rubbing is established in this paper. Considering the effects of the softer coatings painted on the discs and casing, the Lankarani–Nikravesh model is applied to describe the impact force between the compressor disc of the low pressure Rotor and the casing convex point. Meanwhile, the Coulomb model is used to simulate the frictional characteristics. Then the motion equations of the dual-Rotor System with fixed point rubbing are solved by the Runge–Kutta method and the complicated responses at different rotational speeds are analyzed by the 3D waterfall plot, waveform and frequency spectrum. To verify the effectiveness of the dual-Rotor System dynamic model, the experiment of fixed point rubbing is performed on a dual-Rotor test rig. The vibration displacement of the low pressure Rotor is obtained from the data measured in the impact experiment. The numerical results and experimental results indicate that for the dual-Rotor System without rub-impact, the phenomena of beat vibration occur at the certain rotational speed ratio. Moreover, for the case of fixed point rubbing, several combination frequencies in the responses of the dual-Rotor System are identified as the particular fault frequencies.
Lei Hou - One of the best experts on this subject based on the ideXlab platform.
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nonlinear response analysis for an aero engine dual Rotor System coupled by the inter shaft bearing
Archive of Applied Mechanics, 2019Co-Authors: Xiaodong Wang, Lei Hou, Yushu Chen, Xiyu LiuAbstract:This paper focuses on the nonlinear response characteristics of an aero engine dual-Rotor System coupled by the cylindrical roller inter-shaft bearing. The motion equations of the System are formulated considering the unbalance excitations of the two Rotors, vertical constant forces acting on the Rotor System and the gravities. By using numerical calculation method, the motion equations are solved to obtain the nonlinear responses of the dual-Rotor System. Accordingly, complex nonlinearities affected by the bearing radical clearance, the vertical constant force and the rotating speed ratio are discussed in detail. The jump phenomenon, hard resonant hysteresis characteristics are shown for a relatively large bearing clearance, and the soft resonant hysteresis characteristics can be observed for a relatively large vertical constant force. Moreover, the super-harmonic frequency components and the combined frequency components caused by the inter-shaft bearing are observed for both Rotors. But the corresponding frequency components for the low-pressure Rotor are more complex than that for the high-pressure Rotor in same condition. These results would be helpful to recognize the nonlinear dynamic characteristics of dual-Rotor bearing System.
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steady state response characteristics of a dual Rotor System induced by rub impact
Nonlinear Dynamics, 2016Co-Authors: Chuanzong Sun, Yushu Chen, Lei HouAbstract:In this paper, the steady-state responses and their stability of a dual-Rotor System with rub-impact are investigated. The nonlinear equations of motion in eight d.o.f.s are obtained with the consideration of the gyroscopic effect. The multi-harmonic balance combined with the alternating frequency/time domain technique (MHB–AFT) is utilized to calculate the accurate amplitude of each harmonic component. Arc-length continuation is embedded in the MHB–AFT procedure to trace the branch of the periodic solutions, and the Floquet theory is used to discuss the stability of the obtained solutions. Through the numerical calculation, complicated nonlinear phenomena, such as combined harmonic vibrations, hysteresis and resonant peak shifting are obtained when the rub-impact occurs. The result also shows that the control parameters such as mass eccentricity, inter-shaft stiffness and rotational speed ratio make significant but different influences on the dynamic characteristics of the two Rotors. Therefore, the contribution of this study is to provide a further understanding of the steady-state response characteristics of the dual-Rotor System with rub-impact.
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nonlinear response analysis for a dual Rotor System with a breathing transverse crack in the hollow shaft
Nonlinear Dynamics, 2016Co-Authors: Lei Hou, Yushu Chen, Chuanzong SunAbstract:This paper focuses on the nonlinear response characteristics of a dual-Rotor System with a breathing transverse crack in the hollow shaft of the high-pressure Rotor (Rotor 1). A finite element model of the System is set up, and the motion equations of the System are formulated, in which the unbalance excitations of the Rotor 1 and Rotor 2 (low-pressure Rotor) and the time-varying stiffness of the cracked shaft are considered. By using the harmonic balance method, the motion equations are analytically solved to obtain the dynamic responses of the two Rotors. Accordingly, the effects of the crack depth and location on the vibration amplitudes are discussed in detail. The results indicate that when a transverse crack appears, it may bring super-harmonic responses to the Rotor System, and the resonance peaks at the second, third and even fourth subcritical whirling speeds of the two Rotors can be observed. The deeper the crack is, the larger the resonances amplitudes are, especially when the crack is located in the middle of the shaft or around the disks. In addition, the super-harmonic responses of Rotor 1 where the crack located, can also be observed in Rotor 2, which means that the crack signals can be detected in the entire System. Moreover, the numerical computations are carried out by using the Newmark- $$\beta $$ method, which shows great agreement with the previous analytical results. The results obtained in this paper will contribute to the modeling and the fault diagnosis of dual-Rotor Systems with hollow-shaft crack.
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nonlinear vibration phenomenon of an aircraft rub impact Rotor System due to hovering flight
Communications in Nonlinear Science and Numerical Simulation, 2014Co-Authors: Lei Hou, Yushu Chen, Qingjie CaoAbstract:Abstract This paper focuses on the nonlinear vibration phenomenon caused by aircraft hovering flight in a rub-impact Rotor System supported by two general supports with cubic stiffness. The effect of aircraft hovering flight on the Rotor System is considered as a maneuver load to formulate the equations of motion, which might result in periodic response instability to the Rotor System even the eccentricity is small. The dynamic responses of the System under maneuver load are presented by bifurcation diagrams and the corresponding Lyapunov exponent spectrums. Numerical analyses are carried out to detect the periodic, sub-harmonic and quasi-periodic motions of the System, which are presented by orbit diagrams, phase trajectories, Poincare maps and amplitude power spectrums. The results obtained in this paper will contribute an understanding of the nonlinear dynamic behaviors of aircraft Rotor Systems in maneuvering flight.
Bangchun Wen - One of the best experts on this subject based on the ideXlab platform.
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Comparison of Critical Speeds of a Rotor System with Different Types of Finite Elements
2020Co-Authors: Hao Zuo, Xingyu Tai, Bangchun WenAbstract:Abstract. The critical speeds of all kinds of high-speed Rotors must be calculated in project so that all Rotors can work in the safe range of speeds and avoid resonance. A single-span-two-disc Rotor System is investigated by using finite element method based on ANSYS. Natural frequencies are calculated by using beam, solid, mass, shell, beam-solid, beam-shell elements and critical speeds are obtained from Campbell diagram. Finally, the first and second critical speeds are measured by a test rig. Comparison of theoretical and experimental results is performed to assess the accuracy of different element combining forms
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Study on Dynamic Response of Assembly Type Gear-Rotor System
2020Co-Authors: Jishuang Dai, Peng Zhang, Bo Wang, Bangchun WenAbstract:Abstract. The dynamic model of a Rotor System of assembled compressor is established. Based on the single axis analysis, and considering the tilting-pad bearing stiffness characteristics with speed variations, the paper analyses whole System's nature characteristic with gearing mesh factors. It mainly expands with the form of amplitude-frequency drawing and spectrum charts, and examines the dynamic response with each key position of coupled Systems under the two working conditions. The results show that, because of the existence of gear meshing effect, Low speed axis and high-speed axis in the corresponding speed shaft appeared a few larger vibration amplitudes, at high speed axis add unbalance force, can arouse resonance of this axis in the first two order critical speed, but in the other axis don't have obvious display
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oil film instability simulation in an overhung Rotor System with flexible coupling misalignment
Archive of Applied Mechanics, 2015Co-Authors: Xueling Wang, Heqiang Niu, Bangchun WenAbstract:Aiming at the oil-film instability of the sliding bearings at high speeds, this paper Systematically investigates oil-film instability laws of an overhung Rotor System with parallel and angular misalignments in the run-up and run-down processes. A finite element (FE) model of the overhung Rotor System considering the gyroscopic effect is established, and the sliding bearings are simulated by a nonlinear oil-film force model based on the assumption of short-length bearings. Moreover, the effectiveness of the FE model is also verified by comparing our simulation results with the experimental results in the published literature. In the run-up and run-down processes with constant angular acceleration, the effects of parallel misalignment (PM) and angular misalignment (AM) on oil-film instability laws are simulated. The results show that under the perfectly aligned condition, the onsets of the first and second vibration mode instability in the run-down process are less than those in the run-up process due to the hysteresis effect. Under the misalignment conditions, the misalignment of the coupling can delay the onset of the first vibration mode instability and decrease its vibration amplitude. In comparison with the PM, the amplitudes of multiple frequency components are more obvious under the given AM conditions. Moreover, in the run-up and run-down processes with different misalignment conditions, the variation of the dominant vibration energy was observed according to the rotating frequency $$f_{\mathrm{r}}$$ , the first-mode whirl/whip frequency $$f_{\mathrm{n}1}$$ , the second-mode whirl/whip frequency $$f_{\mathrm{n}2}$$ , or the their combinations, such as $$f_{\mathrm{r}}$$ – $$2f_{\mathrm{n}2}$$ .
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stability and steady state response analysis of a single rub impact Rotor System
Archive of Applied Mechanics, 2015Co-Authors: Xingyu Tai, Fuhao Liu, Yang Liu, Bangchun WenAbstract:Using a lumped mass model of a single rub-impact Rotor System considering the gyroscopic effect, the stability and steady-state response of the Rotor System are investigated in this paper. The contact between the Rotor and the stator is described by the simple Coulomb friction and piecewise linear spring models. An algorithm combining harmonic balance method with pseudo arc-length continuation is adopted to calculate the steady-state vibration response of a nonlinear System. Meanwhile, Hill’s method is used to analyze the stability of the System. The nonlinear dynamic characteristics of the System are investigated when the gap size, stator stiffness and unbalance are regarded as the control parameters. The results show that the gap size determines the location of the rub-impact; besides, the smaller gap can improve the stability of the System. The unsteady motion can be found as the stator stiffness increases. Moreover, the unbalance directly affects vibration amplitude, which becomes greater with the increasing imbalance.
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fixed point rubbing fault characteristic analysis of a Rotor System based on contact theory
Mechanical Systems and Signal Processing, 2013Co-Authors: Chaoyang Shi, Qingkai Han, Bangchun WenAbstract:Abstract In this paper, fault characteristics of a single span Rotor System with two discs are investigated when the rubbing between a disc and an elastic rod (a fixed limiter) occurs. First, a finite element (FE) model of the Rotor System is developed, a point–point contact model is established to simulate the Rotor–stator rubbing by simplifying the disc and the rod as two contact points, and then the two models are coupled by contact force. In addition, the augmented Lagrangian method is applied to deal with contact constraint conditions and the coulomb friction model is used to simulate Rotor–stator frictional characteristics. The vibration features of the Rotor System with rubbing are analyzed with respect to the effects of the gaps between the disc and the rod, the contact stiffnesses under three typical cases with different rotating speeds. The simulation results show that different Rotor motions appear, such as period-one motion (P1), P2 and P3 with the increasing rotating speeds, which are in agreement with the experimental measurements. Besides, the gap between the disc and the rod as well as the contact stiffness has a main influence on the vibration intensity and collision rebound forms.
Fulei Chu - One of the best experts on this subject based on the ideXlab platform.
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dynamic behaviors of a geared Rotor System under time periodic base angular motions
Mechanism and Machine Theory, 2014Co-Authors: Qinkai Han, Fulei ChuAbstract:Abstract The dynamic behaviors of a geared Rotor System under time-periodic base motions are studied in this paper. The equations of motion for a spur gear pair System are derived based on the energy theorem and Lagrange's principle. Three base angular motions, including the rolling, pitching and yawing motions, are assumed to be sinusoidal perturbations superimposed upon constant terms. Considering the time-varying base movements and gear meshing, the second order differential equations of the System will not only have time-periodic gyroscopic and stiffness coefficients, but also the multi-frequency external excitations. Numerical method is utilized to obtain the lateral and torsional responses of the geared System under transmission error and unbalanced mass excitations. The effects of various base angular motions on both frequency response and response spectra are discussed in detail. Compared with the other two types of periodic base motions, the rolling base motion has the greatest impact on the dynamic behaviors of the geared System. The transient response of the geared Rotor System is always greatly enhanced no matter which type of base angular motion is in operation.
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steady state response of a geared Rotor System with slant cracked shaft and time varying mesh stiffness
Communications in Nonlinear Science and Numerical Simulation, 2014Co-Authors: Qinkai Han, Jingshan Zhao, Zhike Peng, Fulei ChuAbstract:The dynamic behavior of geared Rotor System with defects is helpful for the failure diagnosis and state detecting of the System. Extensive efforts have been devoted to study the dynamic behaviors of geared Systems with tooth root cracks. When surface cracks (especially for slant cracks) appear on the transmission shaft, the dynamic characteristics of the System have not gained sufficient attentions. Due to the parametric excitations induced by slant crack breathing and time-varying mesh stiffness, the steady-state response of the cracked geared Rotor System differs distinctly from that of the uncracked System. Thus, utilizing the direct spectral method (DSM), the forced response spectra of a geared Rotor System with slant cracked shaft and time-varying mesh stiffness under transmission error, unbalance force and torsional excitations are, respectively, obtained and discussed in detail. The effects of crack types (straight or slant crack) and crack depth on the forced response spectra of the System without and with torsional excitation are considered in the analysis. In addition, how the frequency response characteristics change after considering the crack is also investigated. It is shown that the torsional excitations have significant influence on the forced response spectra of slant cracked System. Sub-critical resonances are also found in the frequency response curves. The results could be used for shaft crack detection in geared Rotor System.
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numerical and experimental investigations of flexural vibrations of a Rotor System with transverse or slant crack
Journal of Sound and Vibration, 2009Co-Authors: Yanli Lin, Fulei ChuAbstract:Flexural vibrations of a Rotor System with transverse or slant crack are analyzed under torsional excitation by numerical simulation and experiment. Numerical results show that combination frequencies of the rotating speed and the torsional excitation frequency are prominent in the flexural responses of a slant-cracked Rotor, but too weak to be identified for a transverse-cracked Rotor. In order to verify the results, an experimental setup is installed to simulate the cracked Rotor System and a special structure is designed to exert the torsional excitation on the cracked Rotor. The experimental results present almost identical characteristic features about the combination frequencies to the numerical results. The numerical and experimental investigations demonstrate these features can be used to distinguish between the transverse crack and the slant crack on the shaft of a Rotor System.
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experimental observation of nonlinear vibrations in a rub impact Rotor System
Journal of Sound and Vibration, 2005Co-Authors: Fulei ChuAbstract:An experimental setup is installed to simulate the Rotor-to-stator rub of the Rotor System. A special structure of stator is designed that can simulate the condition of the full rub. The vibration waveforms, spectra, orbits and Poincare's maps are used to analyze nonlinear responses and bifurcation characteristics of the System when the rub-impact occurs. Experiments with different conditions, including one and two Rotor with single- and multi-disks, are performed. Very rich forms of periodic and chaotic vibrations were observed. The experiments show that the System motion generally contains the multiple harmonic components such as 2X, 3X, etc. and the 1/2 fractional harmonic components such as 1/2X, 3/2X, etc. Under some special conditions, the 1/3 fractional harmonic components such as 1/3X, 2/3X, etc. can be observed as well.
Yushu Chen - One of the best experts on this subject based on the ideXlab platform.
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nonlinear response analysis for an aero engine dual Rotor System coupled by the inter shaft bearing
Archive of Applied Mechanics, 2019Co-Authors: Xiaodong Wang, Lei Hou, Yushu Chen, Xiyu LiuAbstract:This paper focuses on the nonlinear response characteristics of an aero engine dual-Rotor System coupled by the cylindrical roller inter-shaft bearing. The motion equations of the System are formulated considering the unbalance excitations of the two Rotors, vertical constant forces acting on the Rotor System and the gravities. By using numerical calculation method, the motion equations are solved to obtain the nonlinear responses of the dual-Rotor System. Accordingly, complex nonlinearities affected by the bearing radical clearance, the vertical constant force and the rotating speed ratio are discussed in detail. The jump phenomenon, hard resonant hysteresis characteristics are shown for a relatively large bearing clearance, and the soft resonant hysteresis characteristics can be observed for a relatively large vertical constant force. Moreover, the super-harmonic frequency components and the combined frequency components caused by the inter-shaft bearing are observed for both Rotors. But the corresponding frequency components for the low-pressure Rotor are more complex than that for the high-pressure Rotor in same condition. These results would be helpful to recognize the nonlinear dynamic characteristics of dual-Rotor bearing System.
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steady state response characteristics of a dual Rotor System induced by rub impact
Nonlinear Dynamics, 2016Co-Authors: Chuanzong Sun, Yushu Chen, Lei HouAbstract:In this paper, the steady-state responses and their stability of a dual-Rotor System with rub-impact are investigated. The nonlinear equations of motion in eight d.o.f.s are obtained with the consideration of the gyroscopic effect. The multi-harmonic balance combined with the alternating frequency/time domain technique (MHB–AFT) is utilized to calculate the accurate amplitude of each harmonic component. Arc-length continuation is embedded in the MHB–AFT procedure to trace the branch of the periodic solutions, and the Floquet theory is used to discuss the stability of the obtained solutions. Through the numerical calculation, complicated nonlinear phenomena, such as combined harmonic vibrations, hysteresis and resonant peak shifting are obtained when the rub-impact occurs. The result also shows that the control parameters such as mass eccentricity, inter-shaft stiffness and rotational speed ratio make significant but different influences on the dynamic characteristics of the two Rotors. Therefore, the contribution of this study is to provide a further understanding of the steady-state response characteristics of the dual-Rotor System with rub-impact.
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nonlinear response analysis for a dual Rotor System with a breathing transverse crack in the hollow shaft
Nonlinear Dynamics, 2016Co-Authors: Lei Hou, Yushu Chen, Chuanzong SunAbstract:This paper focuses on the nonlinear response characteristics of a dual-Rotor System with a breathing transverse crack in the hollow shaft of the high-pressure Rotor (Rotor 1). A finite element model of the System is set up, and the motion equations of the System are formulated, in which the unbalance excitations of the Rotor 1 and Rotor 2 (low-pressure Rotor) and the time-varying stiffness of the cracked shaft are considered. By using the harmonic balance method, the motion equations are analytically solved to obtain the dynamic responses of the two Rotors. Accordingly, the effects of the crack depth and location on the vibration amplitudes are discussed in detail. The results indicate that when a transverse crack appears, it may bring super-harmonic responses to the Rotor System, and the resonance peaks at the second, third and even fourth subcritical whirling speeds of the two Rotors can be observed. The deeper the crack is, the larger the resonances amplitudes are, especially when the crack is located in the middle of the shaft or around the disks. In addition, the super-harmonic responses of Rotor 1 where the crack located, can also be observed in Rotor 2, which means that the crack signals can be detected in the entire System. Moreover, the numerical computations are carried out by using the Newmark- $$\beta $$ method, which shows great agreement with the previous analytical results. The results obtained in this paper will contribute to the modeling and the fault diagnosis of dual-Rotor Systems with hollow-shaft crack.
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super harmonic responses analysis for a cracked Rotor System considering inertial excitation
Science China-technological Sciences, 2015Co-Authors: Yushu ChenAbstract:In this paper, an investigation on the nonlinear vibration, especially on the super-harmonic resonances, in a cracked Rotor System is carried out to provide a novel idea for the detection of crack faults in Rotor Systems. The motion equations of the System are formulated with the consideration of the additional excitation from an inertial environment as well as the forced excitation of the Rotor unbalance. By using the harmonic balance method, the analytical solutions of the equations with four orders of harmonic exponents are obtained to analyze the nonlinear response of the System. Then through numerical calculations, the vibration responses affected by System parameters including the inertial excitation, the forced excitation, the crack and damping factors are investigated in detail. The results show that the occurrence of the super-harmonic resonances of the Rotor System is due to the interaction between crack breathing and the inertial excitation. Correspondingly, the super-harmonic responses are significantly affected by the inertial excitation and the crack stiffness (or depth). The Rotor unbalance, however, does not make apparent effects on the super-harmonic responses. Consequently, the super-harmonic resonances peaks can be viewed as an identification signal of the crack fault due to the application of the inertial excitation. By utilizing the inertial excitation, the super-harmonic response signals in Rotor Systems with early crack faults can be amplified and detected more easily.
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nonlinear vibration phenomenon of an aircraft rub impact Rotor System due to hovering flight
Communications in Nonlinear Science and Numerical Simulation, 2014Co-Authors: Lei Hou, Yushu Chen, Qingjie CaoAbstract:Abstract This paper focuses on the nonlinear vibration phenomenon caused by aircraft hovering flight in a rub-impact Rotor System supported by two general supports with cubic stiffness. The effect of aircraft hovering flight on the Rotor System is considered as a maneuver load to formulate the equations of motion, which might result in periodic response instability to the Rotor System even the eccentricity is small. The dynamic responses of the System under maneuver load are presented by bifurcation diagrams and the corresponding Lyapunov exponent spectrums. Numerical analyses are carried out to detect the periodic, sub-harmonic and quasi-periodic motions of the System, which are presented by orbit diagrams, phase trajectories, Poincare maps and amplitude power spectrums. The results obtained in this paper will contribute an understanding of the nonlinear dynamic behaviors of aircraft Rotor Systems in maneuvering flight.
