Wyniki wyszukiwania - BazTech

1

Test bed for simulation of magnetic field measurements of low Earth orbit satellites

Gallina A., Zagorski P., Rachucki J.

Mechanics and Control

|

2015

|

Vol. 34, no. 3

47--51

EN

This paper presents a test bed designed to simulate the magnetic environment experienced by a spacecraft in a low Earth orbit. It consists of a spheńcal air bearing located inside a Helmholtz cage. The spheńcal air beańng is used for simulating the microgravity conditions of orbiting bodies, while the Helmholtz cage generates a controllable magnetic field resembling the one surrounding a satellite during its motion. Dedicated computer software is used to initially calculate the magnetic field in an established orbit. The magnetic field data is then translated into current values and transmitted to programmable power supplies that energize the cage. The magnetic field within the cage is finally measured by a test article mounted on the air beańng. The paper provides a descńption of the test bed and test article design. Experimental tests prove the good performance of the entire system.

XX

Artykuł prezentuje stanowisko laboratoryjne służące do symulowania środowiska magnetycznego, w którym porusza się satelita na niskiej orbicie ziemi. Składa się ono ze sferycznego łożyska powietrznego umieszczonego wewnątrz klatki Helmholtza. Łożysko to jest wykorzystywane do symulacji warunków mikrograwitacji doświadczanych przez orbitujące ciała, a klatka Helmholtza do generowania zadanego pola magnetycznego, podobnego do tego, jakie tam występuje. Do symulowania wartości pola magnetycznego na konkretnej orbicie wykorzystywane jest specjalistyczne oprogramowanie. Obliczone za jego pomocą wartości są przekształcone na wielkości prądów, które następnie za pośrednictwem stopni mocy przekazywane są na odpowiednie cewki składające się na klatkę. Następnie pole magnetyczne powstałe w klatce mierzone jest przez testowane urządzenie osadzone na łożysku powietrznym. Artykuł opisuje stanowisko oraz testowane urządzenie. Przedstawia także wyniki eksperymentu potwierdzającego dokładność całego systemu.

2

Modelling and Spherical Air Bearing Based Levitation Design of a Novel M-DOF Actuator

Li Z., Guo Z.

Przegląd Elektrotechniczny

|

2012

|

R. 88, nr 11a

288-291

EN

Supporting and levitation control are important for actuators or motors with complicated structures. Based on the presented configuration design, the simplified torque calculation model and non-linear system dynamic model have been proposed, and spherical air bearing levitation mechanism is developed for alleviating the friction and resistance to improve the dynamic performance of this m-DOF actuator. The fluid field model is built in computational fluid dynamics software. Different structure parameters and conditions are computed and compared with the pressure distribution characteristics. Experiment results show that the actuator can effectively implement 3-DOF motion with the designed levitation modes, and that the proposed approach can be applied to m-DOF actuators of the same kind effectively.

PL

W artykule przedstawiono wyniki prac nad mechanizmem lewitacji w powietrznym łożysku kulistym siłownika typu m-DOF, mających na celu zwiększenie dynamiki poprzez zmniejszenie tarcia i rezystancji. Zaproponowano także uproszczoną metodę obliczania momentu mechanicznego oraz model układu w stanach dynamicznych. Opracowane modele lewitacji zostały poddane weryfikacji eksperymentalnej.

3

A study on the optimal design of air pockets in an air bearing applied tilting index table

Lee M.-J, Lee C.-M

Journal of Machine Engineering

|

2009

|

Vol. 9, No. 2

114--123

EN

The tilting index table has attached to CNC machining center with 3axes, it can be improvement of its performance and its machining efficiency. The tilting index table is a key unit in order to manufacture some non-rotational and 3-dimensional parts, using the conventional machining center. The tilting index table is directly connected to a processing object. Regarding the increase in the deflection of the table, it directly affects processing objects and increases errors and that makes impossible to obtain desired processing precision. Thus, this study performed the shape optimization of air pockets in order to minimize the deflection presented in the existing table. In the numerical optimizing method for implementing optimal design, the general full factorial design and response surface method in the design of experiments were used. A finite element analysis was used for computational experiments in which the finite element analysis was performed by using the ANSYS Workbench, which is a type of commercial FEM tool. In addition, the analysis of the results was performed by using the commercial program, Minitab 15. The results show that the optimum design results is better than those of the initial design.

4

Numerical modeling and design of a wavy thrust bearing

Choy F. K., Braun M. J., Zhao H.

International Journal of Applied Mechanics and Engineering

|

2002

|

Vol. 7, no 3

757-769

EN

The objective of this paper is to present the analytical and numerical development leading to the simulation of a wavy thrust bearings. The analytical formulation is based on the application of the Reynolds equation to the geometry of two parallel circular plates with prescribed boundary conditions at their inner and outer circumferential edges. The upper plate is assumed to be rotating while the lower plate, which is wavy in geometry, is stationary. A numerical procedure based on the discretisation of the Reynolds equation yields a finite difference formulation that reduces the second order partial differential equation to a set of simultaneous algebraic equations. For a given loading condition, the equilibrium position of the rotating plate is evaluated using the Newton-Raphson search, by balancing the applied load with the force generated by the hydrodynamic fluid film resisting pressure. The stiffness of the bearing is then calculated using a numerical small perturbation procedure at the equilibrium position of the upper plate. Finally the transient motion of the journal is evaluated using a numerical integration scheme on the translational and angular acceleration parameters. General and specific conclusions are drawn based on these numerical results.