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“…To better simulate the nonlinear vibration characteristic of the disk-shaft system under the clearance-eccentric coupling faults, a finite element model of the system is established by the finite element analysis software ANSYS which has been demonstrated to as a powerful method in earlier research. 26–28 As shown in Figure 2, the structure parameters of the rotating disk can be described by the internal diameter with 19 mm and external diameter with 76.2 mm, and those of the rotating shaft can be described by the diameter with 19 mm and length with 320 mm. Besides, the radius of the eccentric mass block is assumed as 5 mm for simulating the eccentric fault of the rotating disk.Figure 2.Finite element model of the disk-shaft system.…”
Section: The Disk-shaft System Model Under the Clearance-eccentric Co...mentioning
Clearance between the disk and shaft can lead to the aggravation of the system fault. To solve this problem, a disk-shaft dynamic model with the clearance-eccentric coupling faults is established by the finite element method. Based upon the model, the dynamic characteristics of the system with different influence factors such as clearance and rotating speed are acquired by comprehensive analysis. Meanwhile, the accuracy of the dynamic model is verified by experiment investigations. The results show that frequency components in the spectrum include the shaft’s rotating frequency and high frequency multiplication components. And the sawtooth phenomenon from the trajectory diagram of disk center can be observed. With the increase of rotating speed, the disk-shaft contact stress and strain energy first decrease and then increase, while the speed difference of disk to shaft and vibration amplitude increase, and the number of high frequency multiplication components in the spectrum decreases gradually. Furthermore, with the increase of clearance, the stable values of the disk-shaft contact stress and strain energy decrease, while the vibration amplitude, the number of high frequency multiplication components and speed difference increase gradually, and the trajectory shape of disk center changes from closed circle to hollow ring.
“…To better simulate the nonlinear vibration characteristic of the disk-shaft system under the clearance-eccentric coupling faults, a finite element model of the system is established by the finite element analysis software ANSYS which has been demonstrated to as a powerful method in earlier research. 26–28 As shown in Figure 2, the structure parameters of the rotating disk can be described by the internal diameter with 19 mm and external diameter with 76.2 mm, and those of the rotating shaft can be described by the diameter with 19 mm and length with 320 mm. Besides, the radius of the eccentric mass block is assumed as 5 mm for simulating the eccentric fault of the rotating disk.Figure 2.Finite element model of the disk-shaft system.…”
Section: The Disk-shaft System Model Under the Clearance-eccentric Co...mentioning
Clearance between the disk and shaft can lead to the aggravation of the system fault. To solve this problem, a disk-shaft dynamic model with the clearance-eccentric coupling faults is established by the finite element method. Based upon the model, the dynamic characteristics of the system with different influence factors such as clearance and rotating speed are acquired by comprehensive analysis. Meanwhile, the accuracy of the dynamic model is verified by experiment investigations. The results show that frequency components in the spectrum include the shaft’s rotating frequency and high frequency multiplication components. And the sawtooth phenomenon from the trajectory diagram of disk center can be observed. With the increase of rotating speed, the disk-shaft contact stress and strain energy first decrease and then increase, while the speed difference of disk to shaft and vibration amplitude increase, and the number of high frequency multiplication components in the spectrum decreases gradually. Furthermore, with the increase of clearance, the stable values of the disk-shaft contact stress and strain energy decrease, while the vibration amplitude, the number of high frequency multiplication components and speed difference increase gradually, and the trajectory shape of disk center changes from closed circle to hollow ring.
“…Jin [22] revealed the nonlinear vibration characteristics caused by blade-casing rubbings of a real dual rotor aeroengine. Ma [23,24] showed that the original hardening type nonlinearity may be enhanced or transformed into softening type due to the nonlinear stiffness of the bearing and the rubbing dynamic responses of shaft-blisk-casing system at different speeds, disc imbalance, disc position and speed are solved. Liu [25] studied the dynamic behavior of casing acceleration of the whole aeroengine from the aspect of blade-casing rubbing fault diagnosis.Wei [26] showed that under the excitation of blade loss load, the transient response of the system has obvious impact characteristics, and the stiffness and damping of the rear bearing of the fan have a significant impact on the transient response.…”
Blade disk rotor system is a typical structure of industrial equipments such as aeroengines and gas turbines. The research on the response characteristics and mechanism of the system under the coupling effects of aerodynamic force and blade crack is of great significance to the interpretation of vibration phenomena and diagnosis of faults. From the numerical solution based response characteristic analysis to the kinematics and dynamics based essential response mechanism revealing, from the model based special case study to the Number Theory based general law establishing, in this paper, the response mechanism of blade disk rotor system under the coupling effects of crack and aerodynamic force is studied comprehensively and deeply. Firstly, a simplified dynamic model of typical blade disk rotor system is constructed by using the classical continuous parameter modeling method. Based on the dynamic model, for two structural forms of moving and stationary blades, the typical characteristics of vibration response under the actions of aerodynamic force and blade crack are analyzed by means of numerical solution. Then, from the perspective of kinematics and dynamics, the internal mechanism between the vibration responses and the excitations are revealed. Finally, based on Number Theory, the response characteristics and mechanism of typical structures are summarized, and the general laws of responses with general structural forms are established.
“…Jin 28 revealed the nonlinear vibration characteristics caused by blade-casing rubbing of a real dual rotor aeroengine. Ma 29,30 showed that an original hardening type nonlinearity may be enhanced or transformed into a softening type due to the nonlinear stiffness of a bearing, and the rubbing dynamic responses of the shaft-blisk-casing system at different speeds, disc imbalance, disc position and speed are solved. Liu 31 studied the dynamic behavior of casing acceleration of the whole aeroengine from the aspect of blade-casing rubbing fault diagnosis.…”
The important role of a dynamic model is to study the response characteristics of a system under different parameters or fault states. These response characteristics can be used in many aspects, such as condition monitoring and fault diagnosis. Usually, the response characteristics can be obtained through numerical analysis, but we do not know why such characteristics appear, which hinders our understanding and utilization of vibration. The innovation of this paper is to reasonably explain why such response characteristics appear. First, a simplified dynamic model of a typical blade disk rotor system is constructed by using the classical continuous parameter modeling method. Based on the dynamic model, for two structural forms of moving and stationary blades, the typical characteristics of the vibration response under the actions of aerodynamic force and blade cracks are analyzed by means of numerical solution. Then, from the perspective of kinematics and dynamics, the internal mechanism between the vibration responses and the excitations is revealed. Finally, based on Number Theory, the response characteristics and mechanisms of typical structures are summarized, and the general laws of responses with general structural forms are established.
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