Critical rotation speed for ball milling

AbstractIn an analysis of the rotational properties of more than 1100 B stars (~660 cluster and ~500 field B stars), we determine the projected rotational velocity (V sin i), effective temperature, gravity, mass, and critical rotation speed for each star. The new data provide us a solid observational base to explore many hot topics in this area: Why do field B stars rotate slower than cluster B stars? How fast do B stars rotate when they are just born? How fast can B stars rotate before they become Be stars? How does the rotation rate of B stars change with time? Does the evolutionary change in rotation velocity lead to the Be phenomenon? Here we report the results of our efforts in searching for answers to these questions based on the latest B star census.

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Critical Rotation Speed Calculation and Application Development of Multi-Stage Centrifugal Pumps for Mining

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.130-134.1119 ◽

2011 ◽

Vol 130-134 ◽

pp. 1119-1122

Author(s):

Wei Li ◽

Wei Dong Shi ◽

Xiao Ping Jiang ◽

Yan Xu

Keyword(s):

Rotation Speed ◽

Computational Method ◽

Secondary Development ◽

Centrifugal Pumps ◽

Operational Environment ◽

Application Development ◽

Critical Rotation ◽

Multi Stage ◽

Pump Shaft ◽

Critical Rotation Speed

Multi-stage centrifugal pumps for mining are widely used in mining and smelting industry. The operational environment in coal mine sewage is very harsh, so pump shaft and bearing failure happens frequently. In order to avoid disaster damage caused by failure of the pump shaft due to resonance, it is quite necessary and urgent to calculate critical rotation speed of the pump shaft. A calculation program of critical rotation speed for multi-stage centrifugal pumps for mining was developed using the secondary development tool of Object ARX, to give the computational method of the pump shaft load and static deflection and to achieve calculation of the critical speed, and which avoided the disadvantage of the traditional method. The practical application indicates that the program of critical rotation speed is convenient, intuitive and calculation accurate. It not only improves the work efficiency, but also reduces the labor intensity, so the program will have a good application prospect.

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Stability Control Analysis of Rotating Plates by Finite Element: Emphasis on Slots and Holes

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.3426545 ◽

1972 ◽

Vol 94 (1) ◽

pp. 64-70 ◽

Cited By ~ 14

Author(s):

C. D. Mote

Keyword(s):

Finite Element ◽

Thermal Stresses ◽

Rotation Speed ◽

Stability Control ◽

Control Analysis ◽

Circular Plates ◽

Critical Speeds ◽

Critical Rotation ◽

Critical Instability ◽

Critical Rotation Speed

Accurate finite element procedures have been developed for the vibration of plates with significant membrane stresses. Thermally stressed, rotating circular plates with peripheral edge slots are examined in detail and the influence of slots upon critical rotation speed instability is clarified. In realistic environments slots can considerably increase critical speeds through the reduction of compressive thermal stresses and the introduction of geometrical assymmetry. Optimization of critical instability speeds is discussed.

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The theoretical model for determinig critical rotation speed flexible coupling type SEGE

Scientific Bulletin of Naval Academy ◽

10.21279/1454-864x-18-i1-050 ◽

2018 ◽

Vol XIX (1) ◽

pp. 326-329

Author(s):

Ivanova E

Keyword(s):

Theoretical Model ◽

Elastic Element ◽

Radial Displacement ◽

Rotation Speed ◽

Impact Load ◽

Flexible Coupling ◽

Critical Rotation ◽

Critical Rotation Speed ◽

Elastic Elements ◽

Coupling Type

It this article was studied a flexible coupling with a rubber elastic element. In exploitation period under one direction load, half of all cylinders are working. All of cylinders are made along with a carrying ring. The elastic elements are subjected to compression. On the non-loaded cylinders, a centrifugal force acts to cause their radial displacement. By the slow rubber relaxation of not loaded cylinders, in the case of reverse and impact load it is danger of can be pinched between the metal claws of semi couplings. Radial displacement and critical rotation speeds were determined, for non-loaded cylinders, in the time which is derived pinching the rubber elastic element.

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Stationary Rotation of the Partially Liquid-Filled Unbalanced Rotor under External Friction Force Action

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1040.903 ◽

2014 ◽

Vol 1040 ◽

pp. 903-906 ◽

Cited By ~ 1

Author(s):

E.N. Pashkov ◽

Nikita Martyushev ◽

Pavel G. Yurovsky

Keyword(s):

Rotation Speed ◽

External Friction ◽

Design Parameters ◽

Mathematical Research ◽

Rotating Shaft ◽

Critical Rotation ◽

Unbalanced Rotor ◽

Liquid Type ◽

Critical Rotation Speed ◽

Automatic Balancing

Rotor rotation with liquid layer on the chamber wall under viscoelastic action of the shaft within a planar model is examined in the article. The solution to the problem of determining the deflection of a rotating shaft with liquid filled chamber is given, which is important when designing an automatic balancing device. The issue of the cooperative motion of a solid body and liquid is considered in mathematical research. The set task is performed by applying D'Alembert's principle. The modeling results indicate that an increase in liquid’s mass in a rotor decreases its critical rotation speed; at the same time, the external friction accelerates the system’s self-centering. The developed mathematical models enable us to select the design parameters of a liquid-type autobalancer which operates within the set range of rotor’s angular velocity.

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Production of Dispersion-Strengthened Cu-TiB2 Alloys by Ball-Milling and Spark-Plasma Sintering

Materials Science Forum ◽

10.4028/www.scientific.net/msf.534-536.1489 ◽

2007 ◽

Vol 534-536 ◽

pp. 1489-1492 ◽

Cited By ~ 1

Author(s):

Dae Hwan Kwon ◽

Jong Won Kum ◽

Thuy Dang Nguyen ◽

Dina V. Dudina ◽

Pyuck Pa Choi ◽

...

Keyword(s):

Electrical Conductivity ◽

Ball Milling ◽

Spark Plasma Sintering ◽

Ball Mill ◽

Milling Time ◽

Rotation Speed ◽

Sintering Temperature ◽

Milled Powder ◽

Plasma Sintering ◽

Spark Plasma

Dispersion-strengthened copper with TiB2 was produced by ball-milling and spark plasma sintering (SPS).Ball-milling was performed at a rotation speed of 300rpm for 30 and 60min in Ar atmosphere by using a planetary ball mill (AGO-2). Spark-plasma sintering was carried out at 650°C for 5min under vacuum after mechanical alloying. The hardness of the specimens sintered using powder ball milled for 60min at 300rpm increased from 16.0 to 61.8 HRB than that of specimen using powder mixed with a turbular mixer, while the electrical conductivity varied from 93.40% to 83.34%IACS. In the case of milled powder, hardness increased as milling time increased, while the electrical conductivity decreased. On the other hand, hardness decreased with increasing sintering temperature, but the electrical conductiviey increased slightly

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SENSITIVITY OF STRENGTH, RIGID AND DYNAMIC CHARACTERISTICS OF THE CONSOLE ROTOR TO VARIATION OF DESIGN PARAMETERS

Bulletin of the National Technical University «KhPI» Series Engineering and CAD ◽

10.20998/2079-0775.2021.1.13 ◽

2021 ◽

pp. 104-113

Author(s):

Mykola А. Tkachuk ◽

Andrey Grabovskiy ◽

Nickolay Prokopenko ◽

Mykola M. Tkachuk ◽

Oleksandr Shut ◽

...

Keyword(s):

Dynamic Characteristics ◽

Modulus Of Elasticity ◽

Natural Vibration ◽

Rotation Speed ◽

Design Parameters ◽

Natural Vibration Frequency ◽

Radial And Axial Displacements ◽

Angular Velocities ◽

Air Blower ◽

Critical Rotation Speed

The analysis sensitivity of strength, rigid and dynamic characteristics of the console rotor to variation of design parameters in paper describes The speed of rotation of the shaft, the material of the impeller vary. The dependences of radial and axial displacements on the angular velocities of rotation and the modulus of elasticity of the impeller material are established. For objects of the type of rotary systems with a cantilever arrangement of the impeller, not one, but a set of criteria has been introduced into consideration, which should be taken into account in the research of this type of objects. The tendencies of change of the first and second critical rotational speeds from the modulus of elasticity, rotor rotational frequencies and density of the impeller material are also determined. On this basis, recommendations have been developed for determining the design parameters of the rotor part of the air blower with a cantilevered impeller. Keywords: air blower; critical rotation speed; natural vibration frequency; rotary system; stress-strain state

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Effect of the Ball Milling on the Microstructure and Mechanical Properties of AlN/Cu Composite

Materials Science Forum ◽

10.4028/www.scientific.net/msf.816.15 ◽

2015 ◽

Vol 816 ◽

pp. 15-20

Author(s):

Qian Yu ◽

Mei Hui Song ◽

Yan Li ◽

Xiao Chen Zhang

Keyword(s):

Thermal Conductivity ◽

Electrical Conductivity ◽

Particle Size ◽

Particle Size Distribution ◽

Size Distribution ◽

Ball Milling ◽

Bending Strength ◽

Rotation Speed ◽

Mixing Time ◽

Composite Powders

AlN/Cu composite powder was prepared by ball milling method. Laser particle size analyzer, X-ray diffraction and scanning electron microscopy analysis were performed to study AlN/Cu composite powders. The effects of rotation speed, mixing time, and ball to powder weight ratio (BPR) on the particle size distribution, composition, and morphology were investigated. Results showed that the best ball milling parameters were the rotation speed of 200r/min, mixing time of 6 hours and BPR 10:1. In this best condition, AlN/Cu composite powders would be obtained with optimum particle size distribution and morphology. Then composite powders were pressed at 500MPa and sintered at 1000°C in N2atmosphere. Finally, the composite with an AlN content of 33wt% showed the bending strength of 370MPa, Vikers hardness HV154, thermal conductivity of 182.7W/m°C and electrical conductivity of 3.08MS/m. However, the composite with an AlN content of 25wt% showed the bending strength of 329MPa, Vikers hardness HV122, thermal conductivity of 195W/m°C and electrical conductivity of 6.54MS/m.

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