Circular Flange Research Articles

Finite element prediction of the ultimate axial load capacity of V-section band clamps

Band clamps with a flat bottomed V-section are used to connect a pair of circular flanges to provide a joint with significant axial strength. Despite the wide application of V-band clamps, their behaviour is not fully understood and the ultimate axial strength is currently only available from physical testing. This physical testing has indicated that the ultimate strength is determined by two different types of structural deformation, an elastic deformation mode and a plastic deformation mode. Initial finite element analysis work has demonstrated that analysis of this class of problem is not straightforward. This paper discusses the difficulties encountered when simulating this type of component interaction where contact is highly localised and contact pressures are high.

Electromagnetic Shielding Efficiency Measurement of Composite Materials

This paper deals with the theoretical and practical aspects of the shielding efficiency measurements of construction composite materials. This contribution describes an alternative test method of these measurements by using the measurement circular flange. The measured results and parameters of coaxial test flange are also discussed. The measurement circular flange is described by measured scattering parameters in the frequency range from 9 kHz up to 1 GHz. The accuracy of the used shielding efficiency measurement method was checked by brass calibration ring. The suitability of the coaxial test setup was also checked by measurements on the EMC test chamber. This data was compared with the measured data on the real EMC chamber. The whole measurement of shielding efficiency was controlled by the program which runs on a personal computer. This program was created in the VEE Pro environment produced by © Agilent Technology. HE MEASUREMENT of shielding efficiency of shielded, absorbing and EMC chambers or boxes is usually done by the setup which contains the transmitting and receiving antennas, test signal generator and test signal receiver. As test signal receivers are usually used the EMC receivers or spectral analysers. The measurement itself runs as follows. The receiver with the receiving antenna and also with essential cable is situated inside the chamber or tested box. The transmitter (signal generator) and transmitting antenna are placed at the outer side of the tested object. The location of the antennas is changed around the chamber or box and peak signal on desired frequency is recorded by the spectral analyser. The worst case, when the shielding efficiency is the lowest, is reliably identified by the positioning of antennas around the tested chamber (1) and (2). These chambers are usually made from metal plates. The problem arises immediately when it is necessary to measure the shielding effectiveness of the material from which the chamber or box will be constructed. Especially in the development stage it is not possible to construct the whole chambers or boxes in the huge sizes for accurate measurements. This approach is expensive and also time consuming. There are constructional problems which extend the development of the composite materials. A similar problem appears when it is necessary to know the shielding efficiency of construction materials like bricks, plasterboard, concrete etc. These materials could be also called composite materials, especially during their development stage. The main construction problem of the chambers or boxes from these types of materials for the measurement setups mentioned above is the construction of the doors. The door of these chambers or boxes has usually the main influence on the whole shielding efficiency. In other words, the doors always represent the weakest part of these shielded chambers. Construction of the doors from the concrete-based material is really complicated, in a lot of cases nearly impossible.

Single-drop coacervative microextraction of organic compounds prior to liquid chromatography: Theoretical and practical considerations

Coacervates made of surfactant aggregates, namely aqueous and reverse micelles and vesicles, were firstly used as solvents in single-drop microextraction (SDME) and proposed for the extraction and concentration of chlorophenols prior to liquid chromatography. The formation of coacervate drops in the needle tip of conventional microsyringes depended on the type of intermolecular forces established between the surfactant headgroups making up the supramolecular aggregates; hydrogen bond interactions were strong enough to permit the formation of spherical drops. Stability of 1–50 μL coacervate drops was achieved by introducing the microsyringe needle tip in a PTFE rod, the end of which had been machined out with a heated flanging-tool to get circular flanges (diameters in the range 3.5–6 mm). The parameters affecting the efficiency of single-drop coacervative microextraction (SDCME) were investigated using vesicular coacervates as a solvent and 2-chlorophenol (CP), 2,4-dichlorophenol (DCP), 2,4,6-trichlorophenol (TCP) and pentachlorophenol (PCP) as model analytes. Coacervative microextraction dynamics fit to the general rate equation of liquid–liquid extraction. The effect of variables such as extraction time, drop volume, stirring rate, pH and temperature, on the extraction of chlorophenols was similar to that described for organic solvent drops. Electrolyte concentrations above 0.1 M caused drop instability. Under the optimum conditions, detection limits were in the range 0.1–0.3 μg L −1. The relative standard deviation was between 4.3 and 5.6 at 20 μg L −1 spiked level. The method was applied to the determination of the four chlorophenols in wastewater, superficial water from a reservoir and groundwater and the recoveries were in the range 79 and 106% at 5–20 μg L −1 spiked level.

Prying action in bolted steel circular flange connections

Both the Canadian Institute of Steel Construction (CISC) Handbook of Steel Construction and the American Institute of Steel Construction (AISC) Manual of Steel Construction discuss prying action in tee-type and angle-type connections subjected to tensile force, but no guidance is provided for determining the prying force in bolted steel circular flange connections. However, such connections are very common in leg members of guyed lattice communication towers. To determine the magnitude of the prying forces in such connections, an experimental investigation was conducted on 10 bolted steel circular flange connections. On the basis of the test data, it is proposed that for use with equations in the CISC handbook and AISC manual, the length of the flange tributary to each bolt (bolt pitch) be taken as the circumference of the bolt circle divided by the number of bolts.Key words: bolt pitch, bolted connections, circular flange, prying action, tensile force.

Robotized Flange Assembling with Line Scan Camera Control

The paper describes an intelligent manufacturing system which performs geometric control, manipulation and assembling circular flanges that arrive at high speed on a conveyor belt and are randomly positioned and oriented. The 2D image of incoming flanges is created from a number of line scans executed by a linear camera. A geometry inspection is carried out in real time based on visual measurements of the flange's holes. If the geometry test passed, the location data is transferred to a SCARA-type robot which mounts each of them on a 5-component assembly. A comparative performance analysis for two types of lighting devices is included in the paper.

A simple water-filled plethysmograph for measurement of limb blood flow in humans

Fundamental principles underpinning the study of cardiovascular physiology can be emphasized by measuring blood flow. Plethysmography is an appropriate, noninvasive technique to use but may not be available to some institutions. Therefore, for measurement of blood flow in human limbs, we developed a simple water-filled plethysmograph that may be built with minimal technical support. The device is formed from a plastic cylinder and houses a latex sleeve sealed at either end by means of circular flanges and rubber O-ring seals. Limb volume changes are transcribed using an air-filled piston recorder. This instrument proves to be sensitive and accurately determines limb volume changes over time. Utilizing an appropriate venous occlusion protocol, predicted vascular responses to postural challenge and physical exercise may be followed. In response to a questionnaire, a majority of students (n = 33) agreed that performing blood flow measurements succeeded in relating theory to practice, improved technical and observational skills, and made the learning experience real. This modified plethysmograph proves to be a valuable teaching tool in human physiology classes.

Optimization of open cross section of the thin-walled beam with flat web and circular flange

This paper is devoted to cold-formed thin-walled beams with open cross section. The beam cross section is optimized for a fixed cross section area under strength and stability constraints. Optimal geometrical parameters of the cross section are determined with regard to maximal and safe bending moment. The strength condition is a classical condition applied to the theory of beams for assumed allowable stress. The stability condition serves also as a classical condition for lateral buckling, taking the warping torsion into account. Moreover, the thin-walled beams have been analyzed, for which the shear center, i.e. the main pole, is located in the centroid of the cross section. Results of the numerical analysis are given. Figures present examples of optimal cross sections of the thin-walled beams.

RADIATION IMPEDANCE OF TUBES WITH DIFFERENT FLANGES: NUMERICAL AND EXPERIMENTAL INVESTIGATIONS

End corrections for open-ended cylindrical tubes are determined theoretically and experimentally. For the zero and low frequencies, the wave equation is solved numerically by using a finite difference method. For higher frequencies the complex radiation impedance is measured and for circular flanges, calculated with the boundary element method. For low frequencies the BEM links up with the FDM and for higher frequencies fits with experimental results. Various flanges found in particular in musical instruments are considered: circular flanges of various sizes, spherical and cylindrical flanges, square flanges, the normalised flange (used for loudspeaker testing), short flaring horns and a disk at a certain distance above the open end. Analytical fit formulas are proposed for each case.

Some Remarks on the European Standard Final Draft prEN 1591-1 May 2000 »Flanges and their Joints« Design Rules for Gasketed Circular Flange Connections Part 1: Calculation Method

Some Remarks on the European Standard Final Draft prEN 1591-1 May 2000 »Flanges and their Joints« Design Rules for Gasketed Circular Flange Connections Part 1: Calculation Method

A numerical study on the measurement region of an open-ended coaxial probe used for complex permittivity measurement

The measurement region of an open-ended coaxial probe with circular flange, which is used for measuring the complex permittivity, has been investigated by calculations and measurements. First, the detectable distance between the probe surface and metal plate in the saline solution is clarified by the experiments. Then, the electromagnetic field near the end of the probe, which affects the measurement strongly, has been analyzed by the finite-difference time-domain (FDTD) method. By identifying the measured and calculated results, the measurement region has been determined.

Slope factor法によって定義された接合部局部降伏耐力に関する応力ブロックを用いた評価式 : ノンダイアフラム形式のコンクリート充填円形鋼管柱・梁フランジ接合部の局部引張耐力に関する研究 その2

Design formula has been proposed for local tensile yield strength of unstiffened type connection between concrete filled circular steel tubular column and beam flange. The local connection interface region has been classified to two regions; around the middle region of the flange, and the rest flange edge region. The steel in this edge region has been assumed to be yield fully under the Von Mises' yield condition, In the partially yield middle region, its stress block factor has been assumed to be a function of the full yield strength of the tubular steel relative to the flange's one.

Analytical Study of Thermomechanical Strength of Assemblies with Optional Plane Flanges. The Effect of the Flange Ring Rotation Around the Median Circumference

This paper describes the analytical evaluation of the thermo - mechanical stresses developed in the circular flange assemblies, of optional type, welded to the cylindrical shell of a pressure vessel. In this case, the structure is formed by welding the cylindrical shell on the inner circumference of the flange ring. Based on the theory of deformation compatibility (radial displacements and rotations), the expressions for the evaluation of radial unitary bending moments and the unitary shear forces are deduced. Subsequently, stress values can be calculated and their concentration can be evaluated along the cylindrical shell, below the separation plane of the flange ring.

First record of shape Saturnius papernai Overstreet, 1977 in the Black Sea, with a review of the genus shape Saturnius Manter, 1969 (Digenea, Bunocotylidae)

Saturnius papernai Overstreet, 1977 is recorded from the stomach of Mugil cephalus L. (Osteichthyes, Mugilidae) in the Black Sea (a new geographical record) off the southern part of the Bulgarian coast. The species is redescribed and figured on the basis of the Black Sea specimens. Some amendments to the generic diagnosis are proposed concerning the presence of a uterine seminal receptacle and a posterior (third) circular flange. It is proposed that the occurrence of S. papernai is a feature of one of the three shoals of M. cephalus in the Black Sea, i.e. the Balkan shoal. In a zoogeographical analysis, S. papernai is regarded as a Mediterranean immigrant, probably a characteristic element of only the South-Western Faunistic Region of the Black Sea. A review of the genus Saturnius Manter, 1969 is presented.

Measurement of the radiation impedance of a pipe with a circular flange

The radiation of an open pipe with an infinite flange, as well as that of an unflanged pipe has been explicitly calculated by, respectively, Norris and Sheng [J. Sound. Vib. 135(1), 85–93 (1989)] and Levine and Schwinger [Phys. Rev. 73, 383–406 (1948)]. The radiation of real tubes, i.e., with a finite wall thickness or a finite circular flange, is not accurately known. The aim of the present measurements is to determine the radiation of tubes with various flanges and their frequency dependence. The radiation impedance has been deduced from the measurements of the input impedance of a short tube. As the differences between the different situations can be very small, the impedance sensor must be accurately calibrated. Results are reproducible and are in good agreement with a calculation using a boundary elements method (software, Rayon). It is observed that the curves obtained are not limited by the case of the infinite flange and the case of the unflanged pipe. This is probably caused by a resonance effect due to the diffraction at the edges of the flange.

Design of Tension Circular Flange Joints in Tubular Structures

As the use of circular steel tubes in different structures has increased dramatically in recent years the connections between tubes have become very important. One of the most important and common methods of making connections, especially field connections, in tubular structures is with bolted circular flanges. The design of such a joint under an overall axial tension force requires the determination of flange dimensions and the number and arrangement of bolts. Based on previous theoretical research work and tests on circular flange joints in tubular structures, a new design method for these joints is proposed. Design charts, which are in accordance with the AISC LRFD design specification, have been produced and can be used to decide flange thickness and number of bolts for a joint very easily. These design charts are produced for one tube grade and one flange grade but can be modified for various grades of tube and flange plate materials, both A325 and A490 bolts, and various levels of tension load applied to the connection. It has been shown that the method is accurate, reliable and easy to use.

Automated finite element analysis of circular weld neck flange assemblies

An automated Finite Element computer program to analyse bolted circular weld neck flange and gasket assemblies has been developed. The program is based on an extensive database of British, European and American flange and gasket standards. The program is ideal for identifying problem areas and conducting sensitivity studies

Automated FE analysis of flange assemblies

An automated finite element computer program to analyse bolted circular weld neck flange and gasket assemblies has been developed. The program is based on an extensive database of British, European and American flange and gasket standards. The program is ideal for identifying problem areas and conducting sensitivity studies.

Determination of bolt forces in a circular flange joint under tension force

Formulae for the calculation of bolt forces in circular flange joints under tension are developed and tables and a chart are created to simplify their use. Bolt forces obtained can be used for the design of bolts and flanges in the joints. A range of joints with different dimensions and different bolt preloads are analysed using the formulae and very good agreement between the results and those obtained using finite element analyses has been found.

Experimental study of circular flange joints in tubular structures

Four circular bolted joints with blank flanges have been tested under static tension forces. Different tension forces and bolt preloads have been applied to the joints and bolt forces, displacements and stresses in the joints have been measured. The influences of bolt preloads and flange dimensions on the behaviour of the joints have been investigated. The results obtained have been compared with the results from finite element analyses and mathematical analyses and good agreement has been found.

Ultrastructural study of the spermatozoon in a tropical lucinid bivalve:Codakia orbicularisL.

Summary In Codakia orbicularis, the spermatozoon has a short cylindrical acrosome separated from a long, curved, tapered nucleus by a large subacrosomal region. The cinetic apparatus is made of a complex system of fibrillar processes linking the distal centriolar satellite bodies to a microtubule-like ring which, in turn, is anchored to the plasma membrane through a fibrillar network issued from the secondary satellites at the basal part of the middle-piece where it is encased in a circular flange. The tail contains a normal axonemal pattern; moreover, a large undulating membrane, oriented in the same plane as the central microtubules, is differentiated along the flagellum. The elongated nucleus together with the differentiation of the middle piece and tail represent a significant modification of the primitive type of spermatozoon.