Circular Rail Research Articles

Novel Study of the Rail’s Geometry in the Electromagnetic Launcher

This paper proposed a railgun with sector of circular rails. The center of the sector of circular rails is located at the outside of the railgun bore. The distance between the sectors of two circles is s , opening angle facing outward θ, the inner and outer radius are also assumed to be R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</sub> and R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sub> , respectively. The influence of internal curvature of the rails, the rail thickness and the distance between rails on the current density, magnetic flux density, and inductance gradient (L') have been studied and analyzed using finite-element method. First of all, the different values of θ, s, R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</sub> , and R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sub> are calculated for various values of the area of the railgun bore (S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</sub> ) and cross section of the rails (S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</sub> ). The current density, magnetic flux density, and L' have been calculated for different values. The area of the railgun bore is assumed to be 9 and 10 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and the area of rails are assumed to be 9, 6, 3, and 1 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . In next section, L' is found as a function of s, R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</sub> , and R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sub> for θ =90°, 120°, 150°, and 180°. Finally, L' is compute for rail thickness equals to one-tenth of bore size and θ on the interval [180°, 360°]. According to the achieved results it can be observed the behavior of L' in terms of railgun dimensions changes and it is compared with other geometries.

A rail system for circular synthetic aperture sonar imaging and acoustic target strength measurements: Design/operation/preliminary results

A 22 m diameter circular rail, outfitted with a mobile sonar tower trolley, was designed, fabricated, instrumented with underwater acoustic transducers, and assembled on a 1.5 m thick sand layer at the bottom of a large freshwater pool to carry out sonar design and target scattering response studies. The mobile sonar tower translates along the rail via a drive motor controlled by customized LabVIEW software. The rail system is modular and assembly consists of separately deploying eight circular arc sections, measuring a nominal center radius of 11 m and 8.64 m arc length each, and having divers connect them together in the underwater environment. The system enables full scale measurements on targets of interest with 0.1° angular resolution over a complete 360° aperture, without disrupting target setup, and affording a level of control over target environment conditions and noise sources unachievable in standard field measurements. In recent use, the mobile cart carrying an instrumented sonar tower was translated along the rail in 720 equal position increments and acoustic backscatter data were acquired at each position. In addition, this system can accommodate both broadband monostatic and bistatic scattering measurements on targets of interest, allowing capture of target signature phenomena under diverse configurations to address current scientific and technical issues encountered in mine countermeasure and unexploded ordnance applications. In the work discussed here, the circular rail apparatus is used for acoustic backscatter testing, but this system also has the capacity to facilitate the acquisition of magnetic and optical sensor data from targets of interest. A brief description of the system design and operation will be presented along with preliminary processed results for data acquired from acoustic measurements conducted at the Naval Surface Warfare Center, Panama City Division Test Pond Facility. [Work Supported by the U.S. Office of Naval Research and The Strategic Environmental Research and Development Program.].

Study on Control System of Scan Robot for Circumferential Weld

As the detection efficiency and defect evaluation accuracy of traditional ultrasonic testing of weld is low, in this paper a new control system is developed to accomplish high-efficiency and high-precision evaluation of weld. This system includes Centralized Control, Control of ultrasonic probe and running mechanism. The heart of the system is DSP, and it can control motion of the scan robot along the circular rail and ultrasonic probe along radial direction of circumferential weld, and realize collection and processing of ultrasonic signal by the comprehensive application of computer, automation, precision instrument, motor driver technology. Practice shows that this new system has realized digital, intelligent, automation of ultrasonic weld inspection, and improved Reliability and efficiency of weld inspection.

Frequency response of ordnance replicas across multiple scales

Broad-band, multi-aspect backscatter data obtained using small-scaled and full-scaled replicas of Unexploded Ordnance (UXO) are reported. Data were collected using either linear or circular rail systems. The experiments were performed in: (1) NSWC PCD's small scale test bed (less than 1/16 scaled) which has a simulated bottom, (2) NSWC PCD's Facility 383 9-million gallon fresh water test pool which has a 5-ft sand bottom, and (3) the Gulf of Mexico during GULFEX12 off Panama City, Florida. Data were processed using linear and circular synthetic aperture sonar techniques to generate both images and plots of target strength as functions of frequency and aspect angle. The results from all three experiments are compared to each other and with predictions from Finite-element (FE) analysis. These comparisons are used to assess the utility of alternative methods for generating sonar data from bottom targets of sufficient fidelity to study scattering phenomena and support development of automated target recognition. [Work supported by ONR Code 32 and SERDP.]

Degenerated shell element analysis of circular rail drawing of sheet metal

The prediction of formability in sheet metal forming by numerical simulation allows the manufacturer to reduce the costs of designing tools and to shorten the time‐to‐market cycle. This research aims to create an elastoplastic incremental finite element computer code to simulate a circular rail drawing process of sheet metals. A methodology of formulating an elastoplastic three‐dimensional finite element model, based on the Prandtl–Reuss flow rule and von Mises yield criterion respectively and associated with an updated Lagrangian formulation, is developed to simulate the sheet metal forming process. The shape function derived from a four‐node quadrilateral degenerated shell element is associated into the stiffness matrix to constitute the finite element model. An extended rmin algorithm is proposed to formulate the boundary condition, such as nodal penetration and separation, strain and rotation increment, and altered elastoplastic state of material. The proposed solution for simulation includes algorithms implemented in the finite element code which make it possible to obtain accurate prediction results. Numerical simulation can produce information on the whole deformation history, such as the distribution of thickness, the distribution of stress, the distribution of strain, and the shape after the drawing process. The simulation result was then compared with experimental data to verify the feasibility and reliability in simulation process using this finite element analysis program. It shows good agreement between the simulated results and experimental outcomes. Therefore, the elastoplastic large deformation finite element program can reasonably simulate the circular rail drawing process.

Transition Study of Current Distribution and Maximum Current Density in Railgun by 3-D FEM–IEM

The intelligent estimation method (IEM) is based on approximations which can be described by the configuration and behavioral characteristic of the problem. This paper used the IEM in time domain (IEM-TD) which can be utilized to predict the current distribution and maximum current density. A detailed IEM technique to compute the current distribution over the surface of a rail, current profile around the rail, and maximum current density (Jmax) formula will be presented in this paper. The current distribution is computed for rectangular and circular rails that are shown in color figures. Finally, this paper considers the effect of the rail dimensions and material on these parameters that are shown in several figures. The results of this paper are compared to other published studies and FEM simulation.

Towards a two-dimensional concentration and temperature laser absorption tomography sensor system

The development of a laser absorption spectroscopy sensor system has been described for measurement of two-dimensional (2D) integrated absorbance linear density and temperature distributions. The system incorporates a tunable distributed feedback (DFB) diode laser at 1391.67 nm and a scanning mirror mounted on a moveable carriage, whilst a photodetector and a second scanning mirror are mounted on another moveable carriage. Both carriages move independently along a circular rail with a diameter of 97 cm. The positions of the carriages and the scanning mirrors are controlled by a program via four servomotors. The laser wavelength is scanned over H2O absorption transitions for 11 fan beam projections from five equally spaced points around the circle. 2D images of the integrated absorbance linear density due to water molecules influenced by two heaters were obtained using the algebraic reconstruction technique (the Kaczmarz method). The derived temperature distribution compared well with thermocouple measurements. The experimental results demonstrate that the system based upon a tunable laser absorption sensor can be used for monitoring the 2D distribution of chemical species and temperature in various reactive flow applications.

Study on Contact Rolling Fatigue of Rails : 1st Report, Development of High Speed Rail Testing Machine

The high speed rail testing machine was originally developed in the world to simulate the Shinkansen traffic condition in Japan, especially the contact rolling problems between rail and wheel in a laboratory. Its main features are as follows. This machine is of a unique type and principally consists of a circular rail and two wheels, which contact each other. Test piece : actual bent rail (for example, 12 m×2 pieces), parent metal and welds. Wheel : two actual wheels, easily changeable and hydraulically-operated, running in one direction. Radial load: applied by a simple mechanism with large loading capacity using centrifugal force and oil pressure, and easily variable. Thrust load: generated by vertical oscillation of rotor by oil pressure actuator. Driving system: a wheel driven by oil pressure motor. Brake: DC motor brake and oil pressure brake. Pitch of rail sleeper arrangement; 580 mm. Medium: air, fresh water and sea water, Conditions : the same as those of the Shinkansen.

Study on contact rolling fatigue of rails (1st report, Development of high speed rail testing machine)

The high speed rail testing machine was invented to simulate the Shinkansen traffic conditions, especially the contact rolling problems between rail and wheel, in a laboratory. Its main properties are as follows: This machine was principally consist of a circular rail and two wheels contact rolling internally. Test piece; actual rail (for example, 12 m ×2 pieces), parent metals and welds. Wheel; two actual wheels, easily changeable system by of pressure, one way running direction. Radial load; simple mechanism and large capacity by centrifugal force and oil pressure, easily variable loading system. Thrust load; vertical oscillation of rotor by oil pressure actuator. Driving system; wheel driving. Pitch of rail sleepers; 580 mm. Atomosphere; air, fresh water and sea water. : the same condition as those of Shinkansen.

Cubierta móvil para piscina, en Pensilvania

This swimming pool constitutes part of a recreation centre at Hershey, Pennsylvania, and has the special feature that its roof is movable, so that the pool can be open in summer and enclosed in winter. The roof consists of two semicircular sectors, resting on wheels, which run along a circular rail. The structure of this roof is metallic, made of radial trusses, converging at a central pivot, around which the sectors rotate. Both the enclosing walls, and the roofing units are filled in with foamglass blocks, which are light, waterproof and highly insulating. Their more significant characteristics are a strength of 7 kg/cm 2 and 144 kg/m 3 weight, as well as their small water and heat transmission capacity.

A New Dome for Equatorials

WITH reference to the note in NATURE of January 12 (p. 257), on “A New Dome for Equatorials,” allow me to point out that a rotary dome without a shutter was, as far as I know, first constructed for the observatory in Strassburg. The late Prof. Winnecke, at the meeting of astronomers in Berlin on September 5, 1879, referred to it as follows (Vierteljahrsschrift der Astronomischen Gesellschaft, 14 Jahrgang, p. 334): “In consequence of the construction of the altazimuth, in which the telescope was placed at the end of the axis, the dome of the north tower had to have an unusually large aperture. This was easily accomplished by employing two separate halves of a hemisphere, which could be rolled back on wheels situated above the circular rail, by which means a complete aperture of 2½ metres could be obtained. The mechanism for the movable parts works easily and surely.”

1. Note on certain Vibrations produced by Electricity

“In the course of last summer (1858) I became acquainted with a phenomenon described by Mr Gore in the Philosophical Magazine for June (Supplement, p. 519), of the following nature:—A metal cylinder, supported on two metallic rods or rails, the latter being in connection respectively with the poles of a battery, revolves in either direction, at will, under the action of an electric current copious in quantity. Also continuous rotation of a light copper ball, supported on two circular metallic rails, takes place in either direction at pleasure, depending on the first impulse. It appeared to me very probable that this interesting fact might be applied to explain what is still obscure in the experiment on heated metals, generally known as the “Trevelyan Experiment,” described by Mr Trevelyan, in the “Edinburgh Transactions,” vol. xii., where there is also a paper by myself on the same subject.