Papers by Keyword: Rub-Impact

Abstract: During blade-to-case full annular rub, the frictional thermal response characteristic of blade-to-case was analyzed by the finite element method. A thermal structure coupling finite element model of blade-to-case was established and the transient thermal and structural field was analyzed. The distributions of temperature field and equivalent stress field were obtained on the basis of a certain centrifugal force, friction coefficient and rotate speed of the blade. The numerical simulations have been conducted to show that the heat affected zone (HAZ) locates in a very thin layer of blade-to-case, and the thermal stress is very high in this layer. The thermal effect in the blade-to-case friction process is more obvious as the rotate speed of blade and centrifugal pressure are increased. In practice, it is suggested that the friction thermal effect in the process of rotor-stator rub-impact should not be ignored.

Abstract: Established the unsteady oil-film force with rub-impact fault of rotor-stator-bearing system mechanical models by using Lagrange equation, Application of numerical analysis to study it, concluded that the rotor system in frequency as the only incentive system control parameters of orbit and bifurcation diagrams; analysis of the nonlinear behavior of the response of the system and the failure mechanism, provide a theoretical basis for the safe operation of the rotor system and fault diagnosis. The results show that, when the excitation frequency as the only control parameters, the system exist periodic motion, quasi periodic motion and chaotic motion etc abundant nonlinear phenomena.

Abstract: Established the unsteady oil-film force with rub-impact fault of rotor-stator-bearing system mechanical models by using Lagrange equation, Application of numerical analysis to study it, concluded that the rotor system in frequency as the only incentive system control parameters of orbit and bifurcation diagrams; analysis of the nonlinear behavior of the response of the system and the failure mechanism, provide a theoretical basis for the safe operation of the rotor system and fault diagnosis. The results show that, when the excitation frequency as the only control parameters, the system exist periodic motion, quasi periodic motion and chaotic motion etc abundant nonlinear phenomena.

Abstract: The test rig of two-span rotor-bearing system with rub-impact and crack faults was constructed. The vibration of the rotor-bearing system was observed for different conditions, such as single rub-impact fault, double rub-impact faults and coupling faults of rubbing and crack. The 3D-waterfall spectrum of rotor system was used to analyze the dynamic characteristics of the system during faults. The results indicate there appears 6-superharmonic frequency component on double rub-impact faults. The amplitudes of subharmonic frequencies decrease obviously and it of superharmonic frequencies increases on coupling faults of rubbing and crack, and the superharmonic frequency components are different obviously in different span.

Abstract: We propose the concept of algebraic neural network and introduce the algebraic algorithm in the network-training phase, which transforms the complex nonlinear optimization problem to a set of simple algebraic equations and achieves the best result directly. The experimental results show that rub-impact AE source localization problem is well solved by combining the nonlinear dynamic features and neural network, thus to provide cue to rotor rub-impact fault diagnosis and the application prospects and further research values are promising.

Abstract: The experimental study results show that the system’s nonlinear characteristics, incluing the dynamic responses of the poincare mapping, the bifurcation plots, three-dimensional waterfalls diagrams etc. The effects factors of system experiment are studied and analyzed, including the misalignment and the rub-impact stiffness on system responses. So, the faults characteristics of the misalignment and the rub-impact of the rotation shaft-mechanical seal system on the drainge motor and drainge pump are also gained by the experiment. The dynamic performance of the system show nonlinear characteristics in different working conditions. The rotating shaft-mechanical seal system on the drainge motor and drainge pump can be optimization design and performance prediction based on the studied results of our work. The experiment’s results show that: the multiple frequencies are produced of the rotating shaft-mechanical seal system on drainge motor and drainge pump, and the frequencies of 1-time and 2-time are dominating components under the exciting force effects of misalignment and imbalance. At the fault state of misalignment coupling rub-impact, the multiple frequencies including 2-time, 3-time, 4-time and so on, will be induced under the critical speed. Over the value of the critical speed, will cause the phenomenon of frequency demultiplication and chaos. With rub-impact stiffness value increased, the phenomenon of frequency demultiplication and chaos are induced more frequently; with the degree of misalignment increased, the phenomena of chaos will decrease and the system will tend to be the stable state.

Abstract: The dynamic model of two-span rotor-bearing system with three-coupling faults of rub-impact, crack and pedestal looseness faults was set up, and the influences of faults to nonlinear dynamic characteristics of the system were studied by mapping and continuation comprehensive method. There are many harmonic elements of 1/3, 1/2, 2/3, 1, 3/2 and 2 et al within the sub-critical rotate speed range. But the 3/2 and 2-harmonic elements decrease within the super-critical rotate speed range. It may the main characteristics of the system with three-coupling faults of rub-impact, crack and pedestal looseness. It should notice to diagnosis the three-coupling faults of the system when running within the super-critical rotate speed range.

Abstract: Considering unsteady oil-film force and nonlinear rub-impact force, a dynamic model of crack and rub-impact coupling faults rotor system is developed. Based on the model mentioned, some parameters such as crack depth, eccentricity, as well as a combination parameter which consists of lubricating oil viscosity, rotor weight, bearing clearance and wide-diameter ratio are taken to be considered. According to the bifurcation diagram, the fractal dimension of poincare map and also the trajectory of the shaft center, the complex nonlinear dynamic behaviors are obtained, which may bring up theoretical references for fault diagnosis.

Abstract: The characteristics of the continuous wavelet transform scalogram of the aeroengine vibration signal could show the fault symptomatic in the 2-dimensional space and identify the rub-impact fault of the aeroengine. In order to get the precise feature for fault analysis, the statistical features of the scalogram which incorporated the Tamura vision features were proposed to diagnose the aeroengine rub-impact faults quantitatively. The experiments on the aeroengine test data demonstrate these statistic characteristics of the scalogram effectively diagnose the rub-impact faults.

Abstract: Acoustic emission (AE) techniques are put forward to monitor rub-impacts between rotating rings and stationary rings of mechanical seals by this paper. By analyzing feature extraction methods of the typical rub-impact AE signal, the method combining of wavelet scalogram and power spectrum is found useful, and can used to attribute the feature information implicated in rub-impact AE signals of mechanical seal end faces. Both simulations and experimental research prove that the method is effective, and are used successfully to identify the typical features of different types of rub-impacts of mechanical seal end faces.