scholarly journals Experimental and theoretical research of continuous motion of rotor on anisotropic gapped elastic support

2019 ◽  
Vol 18 (2) ◽  
pp. 156-168
Author(s):  
A. N. Nikiforov ◽  
G. Ya. Panovko ◽  
A. Ye. Shokhin
Keyword(s):  
Contact Forces ◽  
Theoretical Research ◽  
Complex Conjugate ◽  
Flexible Rotor ◽  
Dynamic Features ◽  
Motion Equations ◽  
Displacement Sensors ◽  
Existence Domain ◽  
Direct Tracking ◽  
Full Scale Tests

Kinematic and dynamic features of flexible rotor rolling of an unlubricated uneven-stiffness gapped support are shown with the help of a theoretical model and full-scale tests. A combination of original approaches and well-known analytical and experimental methods is used. In particular, the motion equations are Lagrangian, derived in complex and complex-conjugate coordinates, and their solutions are sought in the exponential form, by excluding contact forces from consideration and by introducing a small parameter. Vibration measurements are not made on the rig frame using accelerometers, but at the source of vibration, i.e. by direct tracking of the rotor axle by a pair of eddy-current contactless displacement sensors installed in a XY configuration. Hence, the preciseness of the experimental data does not depend on the mechanical conductivity of the parts between the source rotor and the receiver sensors. As a result, the frequency, amplitude and existence domain of retrograde precession are reliably determined, and a conclusion is drawn that rolling under a certain combination of parameters is impossible in principle.

Assessment of destressing drilling efficiency using numerical methods: A case-study of Oktyabrsky deposit

2021 ◽  
pp. 26-31
Author(s):  
M. P. Sergunin ◽  
T. P. Darbinyan ◽  
T. S. Mushtekenov ◽  
V. V. Balandin
Keyword(s):  
Rock Mass ◽  
Theoretical Research ◽  
Labor Input ◽  
Efficiency Criterion ◽  
Strength And Deformation ◽  
Low Efficiency ◽  
Full Scale Tests ◽  
Time Required ◽  
Polar Division

Mineral mining in rockburst-hazardous conditions should involve various precautions in compliance with federal regulations and standards. One of the main methods to prevent rock bursts is destressing drilling. In this method, a yielding zone is artificially created. The strength and deformation characteristics in this zone differ from the same characteristics of enclosing rock mass, and redistribution of stresses takes place as a result. Efficiency of destressing drilling is estimated in terms of ore body S-2 in Komsomolsky Mine. The efficiency criterion is selected to be the safety factor of rock mass with and without destressing drilling. Low efficiency of destressing drilling means that this method is readily replaceable by the other techniques of lesser labor input, for example, by reduction in the rate of mining, or by seasoning of underground excavations for some time required for redistribution of stresses to take place. Based on the theoretical research and the conclusions drawn at NorNickel’s Polar Division, the full-scale tests are scheduled for the implementation in order to gradually abandon destessing drilling in rockburst-hazardous Talnakh and Oktyabrsky ore fields. The authors appreciate participation of V. P. Marysyuk from NorNickel’s Polar Division in this study.

Dynamics of Rotor/Bearing System With Flexible Rotor and Flexible Bearing Support

1997 ◽  
Author(s):  
Agnes Muszynska ◽  
Alex Petchenev ◽  
Paul Goldman
Keyword(s):  
Dynamic Stiffness ◽  
Stability Study ◽  
Modal Testing ◽  
Flexible Rotor ◽  
Dynamic Features ◽  
Sweep Frequency ◽  
Response Data ◽  
Lateral Modes ◽  
Force Excitation ◽  
Bearing System

Abstract The paper analyzes, theoretically and experimentally, the lowest four lateral modes of an isotropic rotor/fluid-lubricated bearing system with flexible rotor and flexible bearing support. The parameters of the analytical model of the system are identified using sweep-frequency modal testing of the rotor rig. A nonsynchronous, circular-rotating-force excitation was applied sequentially at the rotor and at the fluid-lubricated bearing casing, in order to generate the response data. The approach used in this study emphasizes the dynamic features of the system which are invariant to the choice of coordinate system. The system is described using Dynamic Stiffness matrix. This provides an advantage of simplicity, allowing a comprehensive stability study for various system parameters.

The Trapezoid Counterweight Method in Dynamic Balance of Symmetric Flexible Rotor

2017 ◽  
Vol 868 ◽  
pp. 201-206
Author(s):  
Han Hui ◽  
Li Na Hao ◽  
Zhang Qi ◽  
Gao Xiang
Keyword(s):  
Dynamic Balance ◽  
Reaction Force ◽  
Resonance Region ◽  
Second Order ◽  
Theoretical Research ◽  
Response Analysis ◽  
Water Pump ◽  
Flexible Rotor ◽  
Order Resonance ◽  
First Order

Steam turbine generator unit, water pump and other high speed revolution symmetric flexible rotor were regarded as research objects in this paper. According to variation characteristic of rotor shaft in rigid and flexible working mode, nine-reel high pressure water pump rotor was analyzed. The former four-order intrinsic frequency of flexible rotor was obtained by modal analysis and harmonic response analysis. The methods of reaction force response and unbalance response were been studied after first order and second order resonance region eliminating in different modes of simple harmonic exciting force. Based on above theoretical research results, trapezoid counterweight method was proposed for dynamic balance of flexible rotor. This method solved problem that rigid dynamic balance of low speed rotor was destroyed after first order and second order resonance region counter weight in dynamic balance of flexible rotor. The dynamic balancing techniques of flexible rotor could be improved the qualities of rotor and its relative products by this method, eliminating the vibration of unbalance mass of products radically.

scholarly journals Resonance Vibration Control for AMB Flexible Rotor System Based onµ-Synthesis Controller

2018 ◽  
Vol 2018 ◽  
pp. 1-16
Author(s):  
Shaolin Ran ◽  
Yefa Hu ◽  
Huachun Wu ◽  
Xin Cheng
Keyword(s):  
Vibration Control ◽  
Control Method ◽  
System Modeling ◽  
Industrial Applications ◽  
Resonance Vibration ◽  
Flexible Rotor ◽  
Displacement Sensors ◽  
Flexible Mode ◽  
Mode Vibration ◽  
And Performance

The resonance vibration control of flexible rotor supported on active magnetic bearings (AMB) is a challenging issue in the industrial applications. This work addresses the application of robust control method to the resonance vibration control for AMB flexible rotor while passing through the critical speed. This model-based method shows great superiority to handling flexible mode vibration, which can guarantee robust stability and performance when encountering modal perturbation. First, the designed flexible rotor-AMB test rig is briefly introduced. Then the system modeling is described in detail including flexible rotor, power amplifier, displacement sensors and magnetic actuator and rotordynamics are analyzed. Model validation is carried out by sine sweeping test. Finally, theμ-synthesis controller is designed. The simulation and experimental results indicate that the designedμ-synthesis controller, which shows great robustness to modal perturbation, can effectively suppress the resonance vibration of flexible rotor and achieve supercritical operation.

Sensitivity and Stability Analysis of Mu-Synthesis AMB Flexible Rotor

2010 ◽  
Vol 164 ◽  
pp. 313-318 ◽  
Author(s):  
Arkadiusz Mystkowski
Keyword(s):  
Weighting Function ◽  
Stability Margin ◽  
Experimental Tests ◽  
Element Model ◽  
Open Loop ◽  
Mode Analysis ◽  
Flexible Rotor ◽  
Displacement Sensors ◽  
Mu Synthesis ◽  
And Performance

The paper presents the sensitivity and stability margin analyses of the flexible rotor supported by active magnetic bearings (AMBs) with the robust optimal vibrations control. The modal representation of the rotor finite element model (FEM) is investigated. Then, the open-loop system of the AMBs flexible rotor is established and critical speed analysis due to variation of bearing stiffness is performed. For the open-loop setup, the non-collocation effect of displacement sensors and magnetic actuators due to control stability problem is considered. The frequency mode analysis of the collocation and non-collocation system is presented. Next, the -synthesis control of 4-DOF AMBs rotor is investigated. The design process of -controllers, which cover uncertainty design and performance shape by chosen weighting function is shortly described. Then, the sensitivity function is calculated and used to evaluate the AMBs rotor stability margin for the -control and the PID control. The performance of the -controller are verified in experimental tests.

Road contact stresses and forces under tires with low inflation pressure

2000 ◽  
Vol 27 (6) ◽  
pp. 1248-1258 ◽  
Author(s):  
Robert A Douglas ◽  
W DH Woodward ◽  
A R Woodside
Keyword(s):  
Single Layer ◽  
Field Trials ◽  
Full Scale ◽  
Contact Forces ◽  
Laboratory Studies ◽  
Inflation Pressure ◽  
Model Study ◽  
Granular Base ◽  
Vertical Contact ◽  
Full Scale Tests

Many field trials have been undertaken to demonstrate the benefits of reducing the inflation pressure of the tires of heavily loaded haul vehicles, but few carefully controlled laboratory studies have been performed. An earlier full scale laboratory study indicated that tire inflation pressure had far less effect on subgrade strains for unpaved, single-layer granular road structures than the tire loading itself, so attention was directed to the behaviour of the granular base at the tire tread - road surface interface. In the present paper, the results of full scale tests performed using a laboratory apparatus designed to measure the dynamic vertical, transverse, and longitudinal contact forces under tires with varying loads and inflation pressures are reported. Vertical contact forces were observed to be highly non-uniform, both across and along the contact patch.Key words: central tire inflation systems, CTI, model study, haul trucks, unbound roads, unpaved roads, access roads.

Research on Dynamic Model of Rotors with Bearing Misalignment

2014 ◽  
Vol 539 ◽  
pp. 3-8 ◽  
Author(s):  
De Xin Ren ◽  
Jie Hong ◽  
Cun Wang
Keyword(s):  
Dynamic Model ◽  
Rotor System ◽  
Flexible Rotor ◽  
Bending Rigidity ◽  
Lagrange Method ◽  
Motion Equations ◽  
Excitation Force ◽  
Aero Engines ◽  
The Relationship ◽  
Mechanics Characteristics

Based on the structural and mechanics analysis of aero-engines rotor system, the dynamic model of the flexible rotor system with multi-supports are presented in order to solve the bearing misalignment problem of rotor system in aero-engines. The motion equations are derived through Lagrange method. The relationship between structural and mechanics characteristics parameters are built up. Finally, the dynamic influence of bearing misalignment on rotor system is divided into three kinds: additional rotor bending rigidity, additional bearing misalignment excitation force and additional imbalance. The equations suggest that additional imbalance excitation force activates the nonlinearity on rotor system and an additional 2× excitation force might appear.

Dynamic modeling and simulation of a flexible-rotor ball bearing system

2021 ◽  
pp. 107754632110343
Author(s):  
Jing Liu ◽  
Changke Tang ◽  
Guang Pan
Keyword(s):  
Modeling And Simulation ◽  
Dynamic Modeling ◽  
Contact Force ◽  
Contact Forces ◽  
Flexible Rotor ◽  
Nonlinear Contact ◽  
Rotor Bearing ◽  
Cubic Polynomial ◽  
Amplitude Characteristics ◽  
Bearing System

This work proposes a comprehensive numerical dynamic model of a flexible-rotor bearing system based on the Hertzian and cubic polynomial nonlinear contact force methods. The model can consider the influences of the nonlinear bearing contact forces and unbalanced force caused by the rotor offset. The displacements and spectrums of the flexible-rotor bearing system from the Hertzian and cubic polynomial nonlinear contact force methods are discussed. The influences of the radial clearance, eccentricity, mass, and deformation of the rotor on the frequency–amplitude characteristics of the flexible-rotor bearing system considering a large speed range are analyzed. The results show that the dynamic and vibration characteristics of the flexible-rotor bearing system from the Hertzian and cubic polynomial nonlinear contact force methods are different. The differences of the frequency–amplitude characteristics between the flexible- and rigid-rotor bearing system are small in a lower speed stage; however, their differences are very large in a higher speed stage. This method can be applied to the nonlinear dynamic modeling and simulation of the flexible-rotor bearing system, which can predict the dynamics and prevent the system failures during the design processing of rotor system.

scholarly journals Soft Robotic Sensing, Proprioception via Cable and Microfluidic Transmission

Electronics ◽  
2021 ◽  
Vol 10 (24) ◽  
pp. 3166
Author(s):  
Keng-Yu Lin ◽  
Arturo Gamboa-Gonzalez ◽  
Michael Wehner
Keyword(s):  
Low Cost ◽  
Pressure Sensors ◽  
Digital Camera ◽  
Contact Forces ◽  
Soft Robotics ◽  
Soft Robot ◽  
Real Time Control ◽  
Time Control ◽  
Displacement Sensors ◽  
Local Pressures

Current challenges in soft robotics include sensing and state awareness. Modern soft robotic systems require many more sensors than traditional robots to estimate pose and contact forces. Existing soft sensors include resistive, conductive, optical, and capacitive sensing, with each sensor requiring electronic circuitry and connection to a dedicated line to a data acquisition system, creating a rapidly increasing burden as the number of sensors increases. We demonstrate a network of fiber-based displacement sensors to measure robot state (bend, twist, elongation) and two microfluidic pressure sensors to measure overall and local pressures. These passive sensors transmit information from a soft robot to a nearby display assembly, where a digital camera records displacement and pressure data. We present a configuration in which one camera tracks 11 sensors consisting of nine fiber-based displacement sensors and two microfluidic pressure sensors, eliminating the need for an array of electronic sensors throughout the robot. Finally, we present a Cephalopod-chromatophore-inspired color cell pressure sensor. While these techniques can be used in a variety of soft robot devices, we present fiber and fluid sensing on an elastomeric finger. These techniques are widely suitable for state estimation in the soft robotics field and will allow future progress toward robust, low-cost, real-time control of soft robots. This increased state awareness is necessary for robots to interact with humans, potentially the greatest benefit of the emerging soft robotics field.

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