High-speed Rotational System Research Articles

Hypergravity prompt thermal crack in 1060 aluminium slat

High-speed rotation instruments that apply gradient hypergravities can induce local variations in structure and thus induce cracking. Rotation-induced hypergravity is a kind of gradient force, and it has a gradient value that depends on distance and local weight. Conventional mechanical testing applies a constant force or periodic force instead of true gradient hypergravity to rotating components. In this study, a dedicated instrument was designed and assembled, and a special sample of 1060 aluminium slats with multiple thinned necks was used to reveal the difference between gradient hypergravity and conventional constant forces. Hypergravity caused more significant damage to the aluminium slat, and the ultimate crack strength was approximately 10% of the strength observed under the constant force applied at the same temperature. All the samples cracked on the inner neck which bears the highest hypergravity. Two types of cracks were categorized based on the relative extension: type Ⅰ mode cracks occurred in the centre of the neck with long extension before cracking under hypergravity more than 3.5 MPa, while type Ⅱ cracks occurred in the root of the neck without long extension before cracking under hypergravity less than 3.5 MPa. Combination of hypergravity and torsional force in high-speed rotation system prompt cracking and exhibit similar microstructure with that under high constant force. Typical cracking and its microstructure under the effects of hypergravity and temperature provided a convenient and practicable method for evaluating service safety of commercial rotating machines for industrial applications and raw alloys.

Barnett effect in paramagnetic states

We report the observation of the Barnett effect in paramagnetic states by mechanically rotating gadolinium (Gd) metal with a rotational frequency of up to 1.5 kHz above the Curie temperature. An in situ magnetic measurement setup comprising a high-speed rotational system and a fluxgate magnetic sensor was developed for the measurement. Temperature dependence of the observed magnetization follows that of paramagnetic susceptibility, indicating that any emergent magnetic field is proportional to the rotational frequency and is independent of temperature. From the proportionality constant of the emergent field, the gyromagnetic ratio of Gd is calculated to be $\ensuremath{-}29\phantom{\rule{0.16em}{0ex}}\ifmmode\pm\else\textpm\fi{}\phantom{\rule{0.16em}{0ex}}5\phantom{\rule{0.16em}{0ex}}\mathrm{GHz}/\mathrm{T}$. This study revisits the primordial issue of magnetism with modern technologies to shed new light on the fundamental spin-rotation coupling.

Analysis on Vibration Characteristic of Dish-Style Separator's Spindle System by Gyroscopic Effect

The paper took dish-style separators spindle system as research object, established a finite element dynamic model for spindle system based on rotor dynamic theory, and then obtained vibration characteristic of spindle system considering gyroscopic effect influenced on critical velocity. The result shows that gyroscopic effect decreases the first and second order eddy frequency of spindle system by 36.2%; spindle rotating velocity meets the design requirements for a flexible shaft. The research result indicates that the method in this paper is available, and has a guide for deeper research on vibration characteristic of high speed rotation system, will reduce research expenditure and test time.

Spin-Rotation Coupling in the Teleparallelism Description in High Speed Rotation System

The spin-rotation coupling can be described by the torsion axial-vector and teleparallelism of general relativity. In a large scale distance, with a high rotating velocity, the tangent velocity will exceed the velocity of light. To overcome that difficulty, we choose a nonuniform and position-dependent angular velocity, e.g. $\Omega(\rho)=\frac{\Omega}{\sqrt[K]{1+(\Omega\rho/C)^{K}}}$ . Based on this choice, we find that the tangent velocity will be less than the speed of light at infinity and never be meaningless. Moreover, the new rotation-spin coupling is derived. And in the case of K=2, it will be consistent with the previous result with the constant angular velocity.

Report based on Fiscal 2000 Diagnostic X-ray Equipment Questionnaire Survey (conditions of X-ray units and similar equipment)

The X-ray Systems Study Group, in an attempt to determine the current status and changes in the state of X-ray equipment, reception systems, and equipment control, conducted investigational research by distributing a questionnaire survey to 400 facilities. The rate of recovery was 33%. The capacity of transformers has been increasing in spite of the three-phase 415 V decrease in the power supply of X-ray equipment. Among high-voltage generators, inverter-type X-ray equipment accounted for 81.3% of units. The ratio of the X-ray tube of a conventional rotational system to that of a high-speed rotational system was 1:3, and 54.9% had target angles of 12 . Many X-ray tubes had a heat capacity of less than 200-300 kHU. The body parts that had the shortest times on radiography were adult chest and pediatric chest. In many cases, the shortest time used was 10 msec. Facilities in which the shortest time was less than 10 msec accounted for almost half of the total number. Facilities where the radiation dose of radiography had decreased showed 1/4 of the digitalization whole. Measurement was carried out when the equipment was bought in 94.9% of facilities, and measurement when the service contract was finished was done in 77.1% of the responding facilities.

High-speed rotation system

A high-speed rotation system susceptible to vibration includes a relatively thin and flexible shaft which has first and second ends, a rotating member disposed on the first end of the shaft, and a planetary gear including a torque-transmitting sun gear which is connected to and restrains the second end of the shaft. A magnetic bearing surrounds at least part of the rotating member for damping the vibration of the rotation system.