A Test Rig for Air Bearings Rotordynamic Coeffcients Measurement

2005 ◽  
Author(s):  
Ernesto Bellabarba ◽  
Sergio Di´az ◽  
Victor Rastelli
Keyword(s):  
Force Measurement ◽  
Dynamic Properties ◽  
Magnetic Bearing ◽  
Suspension System ◽  
Magnetic Suspension ◽  
Identification Algorithm ◽  
External Diameter ◽  
Air Bearings ◽  
Operating Frequency Range ◽  
Stiffness And Damping

This paper describes the design and manufacturing of an experimental facility for measurement of equivalent stiffness and damping of air bearings. For these preliminary tests, the shaft moves only in two perpendicular directions, laying in the rotation plane, thus producing 2×2 characteristic matrices. However, the rig can be easily modified to measure rotordynamic characteristics related to angular motion of the journal and measuring 4×4 matrices. The testing facility uses an experimental magnetic bearing suspension system that allows imposing any given orbit to the shaft, during the testing experiments. All individual parts, as well as the assembly, were dynamically studied to determine their modal response and optimize it according to the test rig’s operating frequency range. The principle of operation is to produce a shaft orbit using the magnetic suspension system and measuring the forces generated on the test bearing housing. Then, the stiffness and damping coefficients are calculated using an iterative parameter identification algorithm (a modification of the IVF method). The force measurement is performed via three load cells placed in a triangle configuration around the test bearing housing. All data is gathered and processed using PC based data acquisition boards and software. The present design allows testing air bearings up to 44 mm in external diameter and a bandwidth of 0 Hz to 1.000 Hz. Preliminary testing was performed on this research that demonstrates the capability of the apparatus to measure the dynamic properties with ease and accuracy.

A Test Rig for Air Bearings Dynamic Characterization

2005 ◽  
Author(s):  
E. Bellabarba ◽  
R. Ruiz ◽  
S. Di´az ◽  
V. Rastelli
Keyword(s):  
Dynamic Properties ◽  
Excitation Frequency ◽  
External Diameter ◽  
Air Bearings ◽  
Equivalent Stiffness ◽  
Dynamic Characterization ◽  
Dynamic Forces ◽  
Present Design ◽  
Rotation Plane ◽  
Stiffness And Damping

This paper describes the design and operation of an experimental facility for measurement of equivalent stiffness and damping of air bearings. The rig uses two magnetic bearings to impose any given orbit to the journal, including displacement in two perpendicular directions on the rotation plane and tilting on the conical mode. Dynamic forces are measured directly on the test bearing housing. Data is gathered and processed using PC based data acquisition boards and software. Only the stiffness and damping coefficients of the fluid film are calculated as a function of the excitation frequency, being it synchronous or not. The present design allows testing air bearings up to 44 mm in external diameter and at frequencies up to 1 KHz. Preliminary testing was performed on this research that demonstrates the capability of the apparatus to measure the dynamic properties with ease and accuracy.

A Prototype Left Ventricular Assist Artificial Heart Pump: An Integrated Permanent Magnet and Active Magnetic Bearing Suspension System

2014 ◽  
Author(s):  
Paul Allaire ◽  
Wei Jiang ◽  
Arunvel Kailasan ◽  
Timothy Dimond
Keyword(s):  
Artificial Heart ◽  
Permanent Magnets ◽  
Magnetic Bearing ◽  
Left Ventricular ◽  
Suspension System ◽  
Magnetic Suspension ◽  
Active Magnetic Bearing ◽  
Low Flow ◽  
Pump Impeller ◽  
Ventricular Assist

The progress in the development of ventricular assist artificial heart pumps is continuing. This paper describes the magnetic suspension for a unique prototype axial flow pump designed for approximately 6 L/min at 100 mm Hg performance with an operating speed of approximately 7,000 rpm. The integrated magnetic suspension design provides a direct non-contact blood flow path through the pump with no obstructions which might create low flow areas and thrombosis (blood clots). The magnetic suspension is a combination of permanent magnets (PMs) and active magnetic bearings (AMBs). There are two radial AMBs which support the four degrees of freedom at the ends of the axial pump impeller and an axial PM thrust bearing. The axial PM bearing supports the direction of the largest fluid force on the impeller. A major objective of artificial hearts is to have extremely low power consumption. Thus the integrated PM and AMB suspension system has an operating magnetic suspension power of approximately 2 watts. The design, numerical modeling, and testing of the magnetic suspension system to support the fluid loads and the g loads are described in the paper.

Stiffness and Damping Evaluation of Air Bearing Sliders and New Designs With High Damping

1999 ◽  
Vol 121 (2) ◽  
pp. 341-347 ◽  
Author(s):  
Q. H. Zengi ◽  
D. B. Bogy
Keyword(s):  
Dynamic Simulation ◽  
Negative Pressure ◽  
Dynamic Properties ◽  
Theoretical Background ◽  
The Other ◽  
Air Bearing ◽  
Air Bearings ◽  
Analysis Method ◽  
Slider Design ◽  
Stiffness And Damping

We apply the dynamic simulation and modal analysis method to analyze the dynamic properties of slider-air bearings. First, the theoretical background and proposed methods are described. Then, five basic types, one of which is first proposed in this paper, of the air bearing surfaces (ABS) are briefly discussed. The dynamic properties of the sliders are investigated, and compared with each other. It is found that a negative pressure slider has the highest stiffness and lowest damping, the TPC and two newly proposed sliders demonstrate higher damping. Finally, the general ABS design problem is briefly discussed. A new advanced slider is designed, analyzed, and compared with the other sliders. The air bearing of the new slider design has larger stiffness and the highest damping of those studied.

Experimental Evaluation of Stiffness and Damping of Slider-Air Bearings in Hard Disk Drives

1999 ◽  
Vol 121 (1) ◽  
pp. 102-107 ◽  
Author(s):  
Q. H. Zeng ◽  
D. B. Bogy
Keyword(s):  
Dynamic Characteristics ◽  
Dynamic Properties ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Air Bearing ◽  
Disk Drives ◽  
Air Bearings ◽  
Transient Responses ◽  
Load Beam ◽  
Stiffness And Damping

The system identification method was applied to experimentally investigate the dynamic characteristics of slider-air bearings in hard disk drives. The transient responses of sliders were measured, and the modal frequencies and damping ratios that are directly related to the stiffness and damping of the bearings were obtained by data processing and parameter identification. The dynamic property of a particular advanced air bearing (AAB) slider was measured and compared with simulation results. It was found that, contrary to usual perception, the suspension assembly significantly affects the dynamic characteristics of the air bearings. Contacts between the load beam and the flexure may introduce a larger damping and nonlinear property. The preliminary results also show that the proposed method is robust for experimentally evaluating the dynamic properties of slider-air bearings.

Design of a combined self-stabilizing electrodynamic passive magnetic bearing support for the automotive turbocharger rotor

2020 ◽  
pp. 107754632093348
Author(s):  
Tomasz Szolc ◽  
Krzysztof Falkowski ◽  
Paulina Kurnyta-Mazurek
Keyword(s):  
Dynamic Interaction ◽  
Magnetic Bearing ◽  
Magnetic Suspension ◽  
Magnetic Bearings ◽  
Main Attention ◽  
Rotor Shaft ◽  
Hurwitz Stability ◽  
Damping Characteristics ◽  
3D Finite Element Method ◽  
Stiffness And Damping

The purpose of this study is to create a concept for what would be a structurally simple and operationally robust support for the automotive turbocharger rotor in electrodynamic passive magnetic bearings. Because this kind of magnetic suspension—in its fundamental version—is dynamically unstable, to avoid the disadvantages contained therein, what is being proposed is the addition of external damping through the employment of the newly designed combined self-stabilizing electrodynamic passive magnetic bearing. The electromagnetic stiffness and damping characteristics of combined electrodynamic passive magnetic bearings have been determined for various shaft rotational speeds by means of the advanced 3D finite element method. In this study, a dynamic interaction between the turbocharger rotor shaft and the passive magnetic suspension is proposed as a support for both the fundamental electrodynamic passive magnetic bearings and the suggested combined self-stabilizing passive magnetic bearings. Here, the main attention is focused on the asymptotic stability of both the rotor shaft suspension variants. The additional damping magnitudes required to stabilize the most sensitive lateral eigenmodes of the object under consideration have been determined by means of the Routh–Hurwitz stability criterion.

Magnetic suspension mechanism using rotary permanent magnets

2020 ◽  
Vol 64 (1-4) ◽  
pp. 977-983
Author(s):  
Koichi Oka ◽  
Kentaro Yamamoto ◽  
Akinori Harada
Keyword(s):  
Permanent Magnets ◽  
Suspension System ◽  
Magnetic Suspension ◽  
Horizontal Force ◽  
Mechanical Contact ◽  
New Type ◽  
Magnetic Suspension System

This paper proposes a new type of noncontact magnetic suspension system using two permanent magnets driven by rotary actuators. The paper aims to explain the proposed concept, configuration of the suspension system, and basic analyses for feasibility by FEM analyses. Two bar-shaped permanent magnets are installed as they are driven by rotary actuators independently. Attractive forces of two magnets act on the iron ball which is located under the magnets. Control of the angles of two magnets can suspend the iron ball stably without mechanical contact and changes the position of the ball. FEM analyses have been carried out for the arrangement of two permanent magnets and forces are simulated for noncontact suspension. Hence, successfully the required enough force against the gravity of the iron ball can be generated and controlled. Control of the horizontal force is also confirmed by the rotation of the permanent magnets.

Research on combination of passive magnetic bearing and mechanical bearing for vertical axis wind turbine

2021 ◽  
pp. 1-16
Author(s):  
Zhu Jun ◽  
Zhang Zhenyi ◽  
Cao Di ◽  
Du Shaotong ◽  
Guo Xiangwei ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Wind Turbine ◽  
Stable State ◽  
Vertical Axis ◽  
Magnetic Bearing ◽  
Suspension System ◽  
Vertical Axis Wind Turbine ◽  
Radial Bearing ◽  
Stable Suspension ◽  
Light Wind

Aiming at the “light wind start, light wind power generation” of vertical axis wind turbine, a new T-shaped radial passive magnetic bearing with high suspension characteristics is proposed. Passive magnetic bearings used in vertical axis wind turbines usually have small bearing capacity and difficult magnetization. The new T-shaped radial PMB can improve the radial bearing capacity, and the three magnetic rings all adopt simple axial magnetization. The new T-shaped radial PMB is combined with mechanical auxiliary bearing to form the suspension system of wind turbine. In the stable state, the suspension system can realize radial and axial stable suspension. The structure and working principle of the suspension system are briefly described. Through the finite element simulation, the characteristics of the new T-shaped radial PMB, the traditional double-ring PMB and the T-shaped PMBs are compared. Taking the high bearing capacity and high stiffness of the new T-shaped radial PMB as the optimization objective, the multi-objective optimization of the new T-shaped radial PMB was carried out by changing its geometric parameters (inner diameter, magnetization length and air gap). The research results show that: Under the same bearing capacity, the volume of the new T-shaped radial PMB is reduced by about 78.64%. Under the same volume, its bearing capacity increased by about 30.7%, and its stiffness increased by about 96.1%. After optimization, its radial bearing capacity increased to 101.38 N, and its stiffness increased to 202.76 N/mm.

scholarly journals Identification of Dynamic Parameters of Pedestrian Walking Model Based on a Coupled Pedestrian–Structure System

2021 ◽  
Vol 11 (14) ◽  
pp. 6407
Author(s):  
Huiqi Liang ◽  
Wenbo Xie ◽  
Peizi Wei ◽  
Dehao Ai ◽  
Zhiqiang Zhang
Keyword(s):  
Negative Correlation ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Field Testing ◽  
The Body ◽  
Structural Vibration ◽  
Pedestrian Dynamics ◽  
Structure Interaction ◽  
Mass Spring ◽  
Stiffness And Damping

As human occupancy has an enormous effect on the dynamics of light, flexible, large-span, low-damping structures, which are sensitive to human-induced vibrations, it is essential to investigate the effects of pedestrian–structure interaction. The single-degree-of-freedom (SDOF) mass–spring–damping (MSD) model, the simplest dynamical model that considers how pedestrian mass, stiffness and damping impact the dynamic properties of structures, is widely used in civil engineering. With field testing methods and the SDOF MSD model, this study obtained pedestrian dynamics parameters from measured data of the properties of both empty structures and structures with pedestrian occupancy. The parameters identification procedure involved individuals at four walking frequencies. Body frequency is positively correlated to the walking frequency, while a negative correlation is observed between the body damping ratio and the walking frequency. The test results further show a negative correlation between the pedestrian’s frequency and his/her weight, but no significant correlation exists between one’s damping ratio and weight. The findings provide a reference for structural vibration serviceability assessments that would consider pedestrian–structure interaction effects.

Sign in / Sign up

Export Citation Format

Share Document