scholarly journals Modelling and Test of an Integrated Magnetic Spring-Eddy Current Damper for Space Applications

Actuators ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 8
Author(s):  
Efren Diez-Jimenez ◽  
Cristina Alén-Cordero ◽  
Roberto Alcover-Sánchez ◽  
Eduardo Corral-Abad
Keyword(s):  
Mechanical Properties ◽  
Eddy Current ◽  
Permanent Magnets ◽  
High Reliability ◽  
Magnetic Suspension ◽  
Space Applications ◽  
Magnetic Spring ◽  
Eddy Current Damper ◽  
Mechanical Suspension

We present the design, manufacturing, and dynamical characterization of a mechanical suspension made by a passive magnetic spring and an eddy current damper integrated into a single device. Three configurations with 2, 3, and 4 permanent magnets axially distributed with opposite polarizations are designed, simulated, manufactured, and tested. Stiffness of 2410, 2050, 2090 N/m and damping coefficient of 5.45, 10.52 and 17.25 Ns/m are measured for the 2-, 3-, and 4-magnets configurations, respectively. The magnetic suspension provides good mechanical properties combined with excellent cleanness and high reliability, which is very desirable in mechanical systems for space applications.

Design of a New Type of Eddy Current Damper With Increased Damping Density

2009 ◽  
Author(s):  
Lei Zuo ◽  
Brian Scully ◽  
Samir Nayfeh
Keyword(s):  
Magnetic Field ◽  
Eddy Current ◽  
High Efficiency ◽  
High Reliability ◽  
Large Mass ◽  
Damping Force ◽  
Eddy Current Damper ◽  
New Type ◽  
Packing Size ◽  
The Magnetic Field

Eddy current dampers have advantages of no mechanical contact, high reliability and stability, but also suffer from the disadvantage of large mass and packing size. In this paper we present a new type of eddy current damper with remarkable high efficiency and compactness. Instead of orienting the magnetic field in a uniform direction, we split the magnetic field into multiple ones with alternative directions so as to reduce the electrical resistance of the eddy current loops and thus to increase the damping force. Experimental results demonstrate that an eddy current damper of 100 × 150 × 140 mm3 has a damping coefficient nearly 3000 Ns/m. The damping density [Ns/m/m3] and dimensionless damping constant are 3–7 times higher than those in literature.

Design and Analysis of a New Type of Electromagnetic Damper With Increased Energy Density

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Lei Zuo ◽  
Xiaoming Chen ◽  
Samir Nayfeh
Keyword(s):  
Magnetic Field ◽  
Analytical Model ◽  
Eddy Current ◽  
High Efficiency ◽  
High Reliability ◽  
Damping Force ◽  
Element Analysis ◽  
Eddy Current Damper ◽  
New Type ◽  
The Magnetic Field

Eddy current dampers, or electromagnetic dampers, have advantages of no mechanical contact, high reliability, and stability, but require a relatively large volume and mass to attain a given amount of damping. In this paper, we present the design and analysis of a new type of eddy current damper with remarkably high efficiency and compactness. Instead of orienting the magnetic field in a uniform direction, we split the magnetic field into multiple ones with alternating directions so as to reduce the electrical resistance of the eddy current loops and increase the damping force and damping coefficient. In this paper, an analytical model based on the electromagnetic theory for this type of eddy current damper is proposed, and a finite-element analysis (FEA) is carried out to predict the magnetic field and current density. Experimental results agree well with the analytical model and FEA predictions. We demonstrate that the proposed eddy current damper achieves a damping density (N s/m m3) and a dimensionless damping constant as much as 3–5 times as those in the literature. The dependence of damping on velocity and frequency is also examined.

scholarly journals Design and Mathematical Analysis of a Novel Reluctance Force-Type Hybrid Magnetic Bearing for Flywheel with Gimballing Capability

2013 ◽  
Vol 2013 ◽  
pp. 1-17 ◽  
Author(s):  
Chun'e Wang ◽  
Jiqiang Tang
Keyword(s):  
Flux Density ◽  
Permanent Magnets ◽  
Magnetic Bearing ◽  
Magnetic Suspension ◽  
Space Applications ◽  
Air Gaps ◽  
Magnetic Circuits ◽  
Maximum Change ◽  
Simulation Results ◽  
Eddy Loss

Magnetically suspended flywheel (MSFW) with gimballing capability fulfills requirements of precision and maneuvers for space applications. A novel reluctance force-type hybrid magnetic bearing (RFHMB) is presented based on analysis of demerits of Lorentz force-type magnetic bearing and common RFHMB. It features that radial and axial magnetic bearing units are integrated into a compact assembly with four separate biased permanent magnets and two conical stators; four radial poles with shoes and rotor made of iron-based amorphousness can reduce eddy loss. Equivalent magnetic circuits of permanent magnets and their control currents are presented. Simulation results indicate flux density fluctuates from 0.272 T to 0.41 T; rotor tilting does not affect the suspension force when rotor only tilts aroundX-axis orY-axis. When rotor drifts inX,Y, orZdirection and tilts aroundX-axis orY-axis simultaneously, force in corresponding directions slightly increases with tilting angle’s enlargement, but the maximum change does not exceed 14%. Additional tilting torque mainly determined by uniformity of flux density in conical air gaps is 0.05 Nm which is far smaller than 11 Nm in common RFHMB; magnetic suspension force is effectively decoupled amongX,Y, andZdirections; results prove that MSFW with gimballing capability theoretically meets maneuvering requirement of spacecraft.

Operation of an Electromagnetic Eddy-Current Damper with a Supercritical Shaft

1994 ◽  
Vol 116 (4) ◽  
pp. 578-580 ◽  
Author(s):  
J. R. Frederick ◽  
M. S. Darlow
Keyword(s):  
Eddy Current ◽  
High Speed ◽  
Eddy Currents ◽  
Squeeze Film ◽  
Future Research ◽  
Rotating Shaft ◽  
Small Disk ◽  
Eddy Current Damper ◽  
Speed Stability

A basic problem inherent with the operation of supercritical shafting is the application of appropriate external damping, which is generally necessary to suppress nonsynchronous instabilities and limit the synchronous response of even a well-balanced shaft. Typically, coulomb or squeeze film-type dampers are used, in which case the damping properties tend to change with temperature, and the necessary contact results in additional torque loading and wear. An alternative damping method currently under investigation is the application of a noncontact electromagnetic damper that dissipates energy through induced eddy-currents generated in a small disk mounted to, and rotating with the shaft (Frederick, 1990). Research is underway on the design and development of a damper of this type that could eventually lend itself to active control applications. The objectives of this investigation are the initial design of a magnetic circuit, an appropriate d-c power supply, and the characterization of preliminary performance experiments on a composite shaft. Damper operation was evaluated during rotating shaft tests and compared to prior tests which involved the use of a permanent magnet eddy-current damper. This Note concerns some interesting results obtained from these preliminary tests. The damper worked well at low speeds, but some high-speed stability problems were encountered. Potential solutions to these problems as well as areas of future research are discussed.

Theoretical investigations on the linear and nonlinear damping force for an eddy current damper combining with rack and gear

2021 ◽  
pp. 107754632098778
Author(s):  
Shouying Li ◽  
Yafeng Li ◽  
Jianzhong Wang ◽  
Zhengqing Chen
Keyword(s):  
Relative Error ◽  
Eddy Current ◽  
Permanent Magnets ◽  
Air Gap ◽  
Numerical Results ◽  
Comsol Multiphysics ◽  
Theoretical Formula ◽  
Iron Plate ◽  
Eddy Current Damper ◽  
Damping Torque

To study the damping characteristics of a new type of eddy current damper with rack and gear recently proposed by the authors, the damping torque for the eddy current damper with rack and gear was theoretically investigated based on some fundamental assumptions, including evenly distributed magnetic field on a conductor plate and no magnetic leakage. A linear relationship between damping torque and velocity was obtained. Numerical simulations by using COMSOL Multiphysics were conducted to evaluate the accuracy of the linear theoretical formula. When angular velocity is less than 30 rad/s, it seems that the linear theoretical results agree well with the numerical results, and maximum relative error between them is about 6.58%. Then, by using COMSOL Multiphysics, a series of parametric studies on damping torque, including the effects of the air gap, the thickness of a back iron plate, the location and number of permanent magnets, and the thickness of a conductor plate, were carried out to further examine the linear theoretical formula. The results show the effects of the air gap and back iron plate on the relative error between linear theoretical and numerical results can be ignored, whereas the location and number of permanent magnets and the thickness of the conductor plate have significant influences on the relative error. Finally, a nonlinear theoretical formula was obtained by introducing three modified coefficients into the linear theoretical formula, and its accuracy was verified in some typical cases. It is proved that there is sufficient accuracy to adopt the nonlinear theoretical formula in preliminary design of the eddy current damper with rack and gear to determine the main structural parameters.

Microstructural and fractographic characterization of B4C-Al cermets tested under dynamic and static loading

1989 ◽  
Vol 47 ◽  
pp. 562-563
Author(s):  
Gyeung Ho Kim ◽  
Mehmet Sarikaya ◽  
D. L. Milius ◽  
I. A. Aksay
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Static Loading ◽  
Carbon Deposition ◽  
Full Density ◽  
Unique Combination ◽  
Strong Component ◽  
Reaction Products

Cermets are designed to optimize the mechanical properties of ceramics (hard and strong component) and metals (ductile and tough component) into one system. However, the processing of such systems is a problem in obtaining fully dense composite without deleterious reaction products. In the lightweight (2.65 g/cc) B4C-Al cermet, many of the processing problems have been circumvented. It is now possible to process fully dense B4C-Al cermet with tailored microstructures and achieve unique combination of mechanical properties (fracture strength of over 600 MPa and fracture toughness of 12 MPa-m1/2). In this paper, microstructure and fractography of B4C-Al cermets, tested under dynamic and static loading conditions, are described.The cermet is prepared by infiltration of Al at 1150°C into partially sintered B4C compact under vacuum to full density. Fracture surface replicas were prepared by using cellulose acetate and thin-film carbon deposition. Samples were observed with a Philips 3000 at 100 kV.

Characterization of interfaces in CVD-coated nicalon fiber-reinforced SiC

1989 ◽  
Vol 47 ◽  
pp. 556-557
Author(s):  
K.L. More ◽  
R.A. Lowden
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Chemical Vapor ◽  
Chemical Vapor Infiltration ◽  
Frictional Stress ◽  
Fiber Reinforced ◽  
Pull Out ◽  
Carbon Coated ◽  
Fiber Matrix

The mechanical properties of fiber-reinforced composites are directly related to the nature of the fiber-matrix bond. Fracture toughness is improved when debonding, crack deflection, and fiber pull-out occur which in turn depend on a weak interfacial bond. The interfacial characteristics of fiber-reinforced ceramics can be altered by applying thin coatings to the fibers prior to composite fabrication. In a previous study, Lowden and co-workers coated Nicalon fibers (Nippon Carbon Company) with silicon and carbon prior to chemical vapor infiltration with SiC and determined the influence of interfacial frictional stress on fracture phenomena. They found that the silicon-coated Nicalon fiber-reinforced SiC had low flexure strengths and brittle fracture whereas the composites containing carbon coated fibers exhibited improved strength and fracture toughness. In this study, coatings of boron or BN were applied to Nicalon fibers via chemical vapor deposition (CVD) and the fibers were subsequently incorporated in a SiC matrix. The fiber-matrix interfaces were characterized using transmission and scanning electron microscopy (TEM and SEM). Mechanical properties were determined and compared to those obtained for uncoated Nicalon fiber-reinforced SiC.

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.

Sign in / Sign up

Export Citation Format

Share Document