scholarly journals Nonlinear Vibration Mechanism of the Marine Rotating Machinery with Airbag Isolation Device under Heaving Motion

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Xiaolei Du ◽  
Ming Li
Keyword(s):  
Nonlinear Vibration ◽  
Mechanical System ◽  
Dynamic Characteristics ◽  
Vibration Isolation ◽  
Rotating Machinery ◽  
Largest Lyapunov Exponent ◽  
Rotor Speed ◽  
Mass Unbalance ◽  
Vibration Mechanism ◽  
Isolation Device

In this paper, we put an investigation into the nonlinear vibration mechanism of the marine rotating machinery with an airbag isolation device under heaving motion. First, we consider the effects of mass unbalance and heaving motion and propose a mathematical model of the marine rotating mechanical system with airbag vibration isolation. Then, the multiple-scale method is conducted to analyze the nonlinear dynamic characteristics of the mechanical system; the frequency-response curves are mainly studied under different parameters, such as the heave excitation, rotor speed, and damping; and the numerical method is also introduced to analyze its dynamic behaviors, such as the steady-state response and its corresponding phase diagram, Poincaré section. The dynamic stability of the system is investigated based on the bifurcations and the largest Lyapunov exponent about rotor speed and heaving frequency. The obtained results indicate complex nonlinear characteristics of the system compared to the system without heaving excitation, which can help us fully understand the dynamic characteristics and parametric optimization as well as structural design of the marine mechanical isolation system.

scholarly journals Choice of Parameters and Stability of Nonlinear Vibration Isolation Device

2016 ◽  
Vol 671 ◽  
pp. 012046 ◽  
Author(s):  
R M Mustafina ◽  
I A Plotnikov ◽  
I V Plotnikova ◽  
O N Tchaikovskaya
Keyword(s):  
Nonlinear Vibration ◽  
Vibration Isolation ◽  
Isolation Device

Vibration Isolation of Rotating Machinery by Parameters Switched Magnetic Bearing and High Static Low Dynamic Stiffness Supports

2018 ◽  
Author(s):  
Yanhui Ma ◽  
Yixin Su ◽  
Suyuan Yu
Keyword(s):  
Rotational Speed ◽  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Design Strategy ◽  
Magnetic Bearing ◽  
Rotating Machinery ◽  
Control Parameters ◽  
Rotor Speed ◽  
Vibration Transmission ◽  
Stiffness And Damping

Vibrations in rotating machinery cause many problems such as excessive noise and the vibration transmission to the supporting structure. In addition, the vibration isolation of the machinery with a wide range of rotational speed is a vital requirement and different to realize in practical engineering. As one of the key components in rotating machinery, bearing is not only the major vibration excitation source, but also the main vibration transmission path. Therefore, the mechanical property of the bearing has a significant effect on the vibration of the rotating machinery. Compared with traditional mechanical bearing, the equivalent stiffness and damping of magnetic bearing can be changed by adjusting its control parameters. On this basis, a novel design strategy of parameters switched magnetic bearing and high static low dynamic stiffness (HSLDS) supports for the vibration isolation of rotating machinery is proposed in this article. The design changes the equivalent linear stiffness and damping of the magnetic bearing by adjusting the control parameters according to the rotor speed, which will improve the vibration isolation capability of magnetic bearing at different rotor speed. Meanwhile, to further reduce the vibration transmission, the rotating machinery was suspended by nonlinear isolator with high static low dynamic stiffness characteristic. As an example, a rotating machinery system consisting of a rigid rotor supported by parameters switched magnetic bearings and high static low dynamic stiffness supports is studied. In this model, the rotor is excited by the unbalance force with different rotational speed. The amplitude of force acted on the base and the maximum relative displacement between the journal and the bearing are used to judge the isolation performance. Simulation results show that the demonstrated the effectiveness of this design strategy and the force transmission is significantly reduced with a wide rotational speed range.

scholarly journals Research on nonlinear vibration isolation device for electro-optic payload

2021 ◽  
Vol 42 (1) ◽  
pp. 16-22
Author(s):  
YUAN Yijie ◽  
◽  
◽  
JI Ming ◽  
ZHANG Weiguo ◽  
...  
Keyword(s):  
Nonlinear Vibration ◽  
Vibration Isolation ◽  
Electro Optic ◽  
Isolation Device

Dynamic characteristics of squeeze-type mount using magnetorheological fluid

2005 ◽  
Vol 219 (1) ◽  
pp. 27-34 ◽  
Author(s):  
Y K Ahn ◽  
J-Y Ha ◽  
Y-H Kim ◽  
B-S Yang ◽  
M Ahmadian ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
Experimental Analysis ◽  
Vibration Isolation ◽  
Dynamic Behaviour ◽  
Electrical Current ◽  
Magnetorheological Fluid ◽  
Test Set ◽  
Mr Fluid ◽  
Set Up ◽  
Stiffness And Damping

This paper presents an analytical and experimental analysis of the characteristics of a squeeze-type magnetorheological (MR) mount which can be used for various vibration isolation areas. The concept of the squeeze-type mount and details of the design of a squeeze-type MR mount are discussed. These are followed by a detailed description of the test set-up for evaluating the dynamic behaviour of the mount. A series of tests was conducted on the prototype mount built for this study, in order to characterize the changes occurring as a result of changing electrical current to the mount. The results of this study show that increasing electrical current to the mount, which increases the yield stress of the MR fluid, will result in an increase in both stiffness and damping of the mount. The results also show that the mount hysteresis increases with increase in current to the MR fluid, causing changes in stiffness and damping at different input frequencies.

The Method for Determining the Vibration-Damping Elements for the Mechanical System to Obtain the Desired Amplitude Value

2014 ◽  
Vol 657 ◽  
pp. 644-648 ◽  
Author(s):  
Andrzej Dymarek ◽  
Tomasz Dzitkowski
Keyword(s):  
Mechanical System ◽  
Dynamic Characteristics ◽  
Vibration Reduction ◽  
Mechanical Systems ◽  
Vibration Damping ◽  
Displacement Velocity ◽  
Synthesis Methods ◽  
Resonance Frequencies

The paper presents the use of synthesis methods to determine the parameters of passive vibration reduction in mechanical systems. Passive vibration reduction in a system is enabled by units called dampers whose values are determined on the basis of the method formulated and formalized by the authors. The essence of the method are, established at the beginning of a task, dynamic characteristics in the form of the resonance and anti-resonance frequencies, and amplitudes of displacement, velocity or acceleration of vibration.

Vibration control of an unbalanced system using a quasi-zero stiffness vibration isolator with fluidic actuators and composite material: An experimental study

2022 ◽  
pp. 107754632110514
Author(s):  
Sivakumar Solaiachari ◽  
Jayakumar Lakshmipathy
Keyword(s):  
Composite Material ◽  
Nonlinear Vibration ◽  
Vibration Isolation ◽  
Basalt Fiber ◽  
Experimental Investigations ◽  
Vibration Isolator ◽  
Coil Spring ◽  
Linear Type ◽  
Fluidic Actuators ◽  
Isolation Performance

In this study, a new type of vibration isolator based on fluidic actuators and a composite slab was tested experimentally with an unbalanced disturbance. Quasi-zero stiffness vibration isolation techniques are advanced and provide effective isolation performance for non-nominal loads. The isolation performance of the proposed isolator was compared to that of a nonlinear vibration isolator equipped with fluidic actuators and a mechanical coil spring (NLVIFA). The NLVIFA system is better suited to non-nominal loads; however, the mechanical spring axial deflection leads to limited amplitude reduction in the system. To address this issue, a cross buckled slab was developed to replace a mechanical coil spring for absorbing vertical deflection by transverse bending, which is made of a specially developed composite material of Basalt fiber reinforced with epoxy resin and enhanced with graphene nano pellets. This current study was concerned with the theoretical analysis and experimental investigations of the proposed nonlinear vibration isolator with fluidic actuators and composite material (NLVIFA-CM), which performs under quasi-zero stiffness characteristics. Because of its reduced axial deflection, the theoretical and experimental results show that the NLVIFA-CM system outperforms the NLVIFA system and other linear type vibration isolators in terms of isolation performance. Furthermore, the proposed vibration isolator makes a significant contribution to low-frequency vibration.

scholarly journals Research on dynamic characteristics of plate under pedestrian excitation based on Newmark-β

2018 ◽  
Vol 37 (4) ◽  
pp. 682-699
Author(s):  
Xinfang Ge ◽  
Weirong Wang ◽  
Wei Yuan
Keyword(s):  
Rectangular Plate ◽  
Dynamic Characteristics ◽  
Vibration Isolation ◽  
Great Influence ◽  
Interaction Model ◽  
Vertical Direction ◽  
Structural Vibration ◽  
Normal Walking ◽  
Plate Structure ◽  
Pedestrian Excitation

Development of micro and ultra-precision machining, precision instruments and equipment, precision assembly and testing has put forward more and more high requirements to vibration isolation on environmental elements, especially the pedestrian excitation generated by workers' normal walking. Therefore, it is very important to study the pedestrian excitation's influence on vibration characteristics of precision instruments and equipment. In this study, dynamic model including mathematical model of pedestrian excitation, interaction model between pedestrian and rectangular plate structure, the human–plate coupled dynamic equation in vertical direction of pedestrian–plate structure was established. And then we use the Newmark-β method to solve the time-domain step-by-step integration of the first four order modes' dynamic equations and study the influence of the linear notion trajectory along the central axis direction on the dynamic characteristics of the rectangular plate. By simulation, we discussed plate structure response under different conditions, including plate structure displacement and acceleration response under the single person excitation with different velocities, under normal walking velocity with different number of pedestrians and under this case of different distance between two pedestrians. The results show that the structural vibration induced by pedestrian excitation has great influence on dynamic characteristics of plate.

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