Angles Of Taper Research Articles

Comparative Evaluation of Structural Systems for Tapered Tall Buildings

Structural efficiency of tapered tall buildings has been well recognized, and many tall buildings of tapered forms have been built throughout the world. Tall buildings are built with an enormous amount of building materials. As one of the most efficient structural forms for tall buildings, the contribution of tapered forms to saving structural materials coming from our limited natural resources could be significant. Structural design of tall buildings is generally governed by lateral stiffness rather than strength. This paper systematically studies the structural efficiency of tapered tall buildings in terms of lateral stiffness. Tall buildings of various heights and angles of taper are designed with different structural systems prevalently used for today’s tall buildings, such as diagrids, braced tubes, and core-outrigger systems. The heights of the studied buildings range from 60 to 100 stories, and the corresponding height-to-width aspect ratios in their non-tapered prismatic forms range from 6.5 to 10.8. The angles of taper studied are 1, 2, and 3 degrees. Gross floor area of each building of the same story height is maintained to be the same regardless of the different angles of taper. Based on design studies, comparative evaluation of the various structural systems for tapered tall buildings is presented.

Taper’s angle influence on the structural integrity of single-lap bonded joints

The effect of conventional inside and outside tapers was addressed considering angles of 30°, 45° and 60°. The strain state of the joints was analyzed with an optical technique and an electrical gauge. Parametric studies were performed using the numerical method to investigate the role of taper geometries and taper angles on the stress distributions of adhesive joints. The statistical analysis of the numerical stresses reported within this paper allowed to get conclusions about which of the taper geometries conducted to higher adhesive compression levels. Experimental results showed that the reduction of the angles of taper increases the joint strength for all types of tapers and this was in agreement with the numerical results obtained from finite element analysis. The joints with outside tapers have higher tensile/shear strength than the joints with reverse or normal adhesive tapers. Local and global strains of the joints with the normal adhesive tapers showed different values, especially for the taper angle of 60°. The mid-line of the adhesive layer of the inside and adhesive tapers showed similar average shear-peel load levels, but because the inside taper geometry induces more compression of the adhesive and the position of the peaks of shear and peel stresses is not coincident, the inside tapering showed to be preferable.

Effect of Surface Roughness of Pure Aluminium A1100 on the Cold Work Extrusion by Using Different Angles of Taper Die

The study presented in this paper is focused on the effect of surfaces roughness of pure aluminium A1100 on the cold work extrusion process by three different angles of taper die. Different angles of taper die will affect the surface roughness of the workpiece. To protect the surface and to reduce friction, lubricants are often used in extrusion process [1]. Different lubricants may have different optimum taper die angle that are suitable to be applied. Two types of materials used in this experiment are steel SKD 11 for taper die and aluminium A1100 for workpiece and different angles applied are 30o, 45o, and 60o. Moreover, with respect to each angle, three different types of lubricants were used which are Daphne Draw S Series, Palm Olein, and EFB bio oil. The Universal Testing Machine and Surface Roughness Tester were used in this experiment. The result obtained from the experiment shows that at 30o of taper die angle were producing the smooth product surfaces for each lubricant and Daphne Draw S Series could reduce the surface roughness compared to other lubricant test.

Experimental study of non-newtonian fluids in conical annular channels

Intensive development of chemical technology makes current problems of hydrodynamics flow abnormally viscous fluids in cylindrical annular channels and conical annular channels. Feature of such flows is the need to consider the influence of the flow not only reological properties of the fluid, but also the effect of the inertial forces of the convective acceleration. This article has one of the first attempts to conduct similar investigations of and to obtain views and recommendations on how to calculate the parameters of such flows. In the basis of work the experimental studies to allow a physical simulation of hydrodynamics flow in doubly connected domains with different angles of taper forming surfaces. The article presents the resulting experimental dependence, characterized by a loss of energy in conical annular channels, depending on the rheological properties of model fluids and their offers on the basis of the calculation of the coefficient of hydraulic friction. Are presented according to the coefficient of hydraulic friction λ of the Reynolds number Re for conical annular channels with various law changes the cross-section along its length. Such studies may be useful in the design-governmental equipment for the processing of polymeric materials in the extrusion line.

Effect of the Geometry of the Working Chamber of a Cylindrical-Conical Hydrocyclone on the Non-Newtonian Fluid Dynamics

Numerical simulation is used to study the dynamics of non-Newtonian free-surface flow in a cylindrical-conical hydrocyclone. For different angles of taper of the conical section of the hydrocyclone, the pressure and velocity distributions are calculated, together with the dependence of the fluid film thickness on the axial coordinate. The effect of the rheological properties of the fluid and the controlling similarity parameters on the flow dynamics is studied.

A study of the dimensions and taper angles of the medullary canals of the proximal and middle phalanges

The morphology and dimensions of the medullary canals of the proximal and middle phalanges have been studied with particular interest shown to the angle of taper of these canals. Measurements of 50 cadaveric fingers were taken from computer aided tomographic images using AutoCAD software. Tangents were fitted to the inner cortices in two orthogonal planes and the angles between them were measured. The angles of canal taper in the proximal phalanx were remarkably similar for each digit. This was also true for the middle phalanx of the index, middle and ring fingers but the taper of the middle phalanx of the little finger was found to be different.

Oscillatory flow of a viscous fluid through converging-diverging orthotropic tethered tubes

A theoretical investigation of the propagation of pressure waves through uniformly converging and diverging thin-walled orthotropic elastic tubes filled with a Newtonian fluid is made in this paper, by considering the flow to be laminar and unsteady. Axisymmetric solutions of the differential equations that govern the motion of the fluid and the solid elastic wall are obtained. The outer surface of the wall is taken to be free of tractions. By using the solutions, a complicated form of transcendental equation is derived, that serves as a dispersion equation and puts forth a relation between the frequency and the wave number. This equation is solved by employing both analytical and numerical techniques. Numerical values of the pressure gradient, mean axial velocity, radial velocity, flow rate, amplitude ratio, phase velocity, and wave length have been computed for different angles of taper for a particular situation. It is felt that the results presented in the paper will find adequate applications in the study of blood flow through certain arterial segments, particularly in investigating the propagation of small amplitude harmonic waves, generated due to the flow of blood when the wave length is large compared to the radius of the arterial segment.

Attenuation of Flow Disturbances in Tapered Arterial Grafts

Flow disturbances in tapered arterial grafts of angles of taper between 0.5 and 1.0 deg were measured in vitro using a pulsed ultrasound Doppler velocimeter. The increase in transition Reynolds numbers with angle of taper and axial distance was determined for steady flow. The instantaneous centerline velocities were measured distal to a 50 percent area stenosis (as a model of a proximal anastomosis), in steady and pulsatile flow, from which the disturbance intensities were calculated. A significant reduction in post-stenotic disturbance intensity was recorded in the tapered grafts, relative to a conventional cylindrical graft. In pulsatile flow with a large backflow component, however, there was an increase in disturbance intensity due to diverging flow during flow reversal. This was observed only in the 1.0 deg tapered graft. These findings indicate that taper is an important consideration in the design of vascular prostheses.

Comparison of pressure losses in steady non-Newtonian flow through experimental tapered and cylindrical arterial prostheses

The use of an arterial prosthesis with a tapered lumen has several important advantages; for example, improved stability of flow, increased wall shear and better matching of its size with that of the host vessel. Tapering may, however, lead to increased energy losses, particularly if the angle of taper is large and the flow is high. This study is concerned with the determination of pressure drop for steady and laminar converging flow through rigid wall models of tapered arterial grafts. The angles of taper examined ranged from 0.5° to 1.0°. Aqueous solutions of polyacrylamide, with non-Newtonian viscous properties similar to those of blood, were used. The pressure drops across the tapered tubes were measured and the data were measured and the data were related to the pressure loss in cylindrical tubes of equivalent dimensions. Expressions for the ratio of the pressure drop in a tapered tube to that in a cylindrical tube for steady flow of a power law fluid were derived; there was good agreement between the predicted and the measured pressure drop ratios over a wide range of flows. The results of this study may be applied to the design of tapered arterial grafts. The pressure losses to be expected in tapered bypass grafts having various dimensions can easily be computed.

Pressure losses in non-Newtonian flow through rigid wall tapered tubes.

Pressure drop and pressure gradient were measured in steady Newtonian and non-Newtonian flow through tapered tubes having angles of taper, alpha, between 0.5 degree and 1.25 degrees. Aqueous solutions of polyacrylamide, characterized as power law fluids, were used for the non-Newtonian flow measurements. These solutions had power law parameters similar in magnitude to those of blood. The pressure drop-flow rate data compared well with the predictions of a semi-empirical flow model over a large range of flow rates (Re alpha up to 10 for Newtonian flow and 5.7 for non-Newtonian flow). The pressure gradient increased with distance, z, into the taper as the radius decreased. The linear relationship between pressure gradient and z, derived by Oka (Biorheology, 10, 207-212, 1973) was found to be valid only when alpha z was small. For the tapered tubes examined here, agreement was confined to the region near the inlet. If higher order terms in alpha z were taken into account the agreement was extended further into the taper. However, under higher flow conditions, when the inertial losses are not negligible, the semi-empirical model provides much better estimates of pressure gradient.

Tool Fracture Probability of Cutting Tools Under Different Exiting Conditions

A large number (150) tungsten carbide (6 weight percent) cutting edges were used to make single cuts in AISI 4340 steel (HB = 235 kg/mm2) at a cutting speed of 200 fpm (61 m/min) and a variety of feeds and entrance and exit angles of workpiece taper. A map is presented showing types of brittle tool fracture occurring at exit for a wide range of feeds and exit angles. Fractures were of two types: 1) those due to very sudden unloading of the tool at exit, and 2) those due to metal adhering strongly to the tool face following a cut. Reasons for the two types of exit failure are briefly discussed.

A theoretical and clinical investigation into the taper achieved on crown and inlay preparations.

The minimum angles of taper that can in theory be formed to various preparations were established for representative dental preparations and operating distances. These values were compared with the taper of dental preparations formed both under laboratory conditions and in clinical practice, the latter by measurement of taper on the dies of clinically successful crowns and inlays. A possible explanation for the discrepancy noted between recommended degrees of taper and the tapers produced under clinical conditions was considered to be due to the requirement by a dental surgeon to avoid forming undercuts to the line of withdrawal of a cast intracoronal or extracoronal retainer.

Experimental determination of the elastic-plastic boundary

An experimental method is investigated by which the elastic-plastic boundaries of a rectangular tapered beam having a single concentrated load acting at its free end can be determined. The method, based on the Tresca yield criterion, employs the isochromatics of the photoelastic stress pattern in birefringent coatings and is used to locate experimentally the elastic-plastic boundaries in a series of aluminum beams of small angles of taper. To check these boundary locations theoretically, the simple mechanics-of-materials elastic-plastic beam theory is used, and the comparisons of theoretical and experimental results are shown.

FREE-MOLECULE FLOW AND CONVECTIVE-RADIATIVE ENERGY TRANSPORT IN A TAPERED TUBE OR CONICAL NOZZLE

An analysis is presented of the fluid flow and heat transfer characteristics of a highly rarefied gas passing through a tapered tube or conical nozzle. The rate of mass throughflow has been determined as a function of the pressures and temperatures of the system and of the tube dimensions. It is found that, at moderate and large angles of taper, the mass throughflow is affected little by increases in tube length, except for short tubes. At small taper angles, the mass throughflow is more sensitive to tube length. The energy transport analysis includes simultaneous convection and radiation. Numerical results have been found for the adiabatic wall temperature. It is found that, for surfaces that can be approximated realistically as diffuse emitters and reflectors of thermal radiation, the results differ little from those for pure radiation.

Societies and Academies

LONDON. Institute of Metals, Sept. 15 (Annual Autumn Meeting, Zurich).—A. J. Murphy: The constitution of the alloys of silver and mercury; with an appendix by G. D. Preston on the X-ray examination of the system silver-mercury. Progressive additions of mercury to silver cause a continual reduction in the temperature of the initial freezing point down to -38.8° C., the freezing point of mercury. No alloy in the series has a freezing point lower than that of pure mercury. Silver can retain in solid solution 55 per cent by weight of mercury at 276° C., the amount probably increasing somewhat at lower temperatures.—A. von Zeerleder: Influence of variations in heat-treatment and ageing on duralumin. Quenching in hot water or in oil causes less deformation, and if the temperature of the quenching medium, as well as the ageing temperature, be 50°C, there is no disadvantageous influence on the physical properties. Measurements of the electrochemical potential, electrical conductivity, tensile and corrosion properties showed that a temperature of 145° C. (293 ° F.) had a decidedly disadvantageous influence.—W. E. Alkins and W. Cartwright: Experiments in wiredrawing. (1) Behaviour of a composite rod. Composite round rods of annealed copper, built up by drawing a number of tubular layers of equal thickness over a central solid core, have been drawn in drafts of varying severity through straight-sided dies of three different angles of taper. Butt ends when drawn through the dies become concave without showing any steps between the layers; the concavity increases with the angle of taper of the die and also with the amount of reduction at the draft. All the layers undergo a proportionate reduction in thickness and therefore the same relative reduction in area of cross-section.—E. L. Francis and F. C. Thompson: The drawing of non-ferrous wires. The power required to draw wire is directly proportional to the maximum stress of the original material. With tungsten carbide dies, the pull required is practically independent of the speed of drawing over a wide range. A comparison is made between the efficiency of steel, carbide, and diamond dies.—H. W. Brownsdon and E. H. S. van Someren: Application of the spectrograph to the analysis of non-ferrous metals and alloys. The possibilities and limitations of spectrographic methods are reviewed. Methods for the routine spectrographic examination of brass and some lead alloys are outlined, and tables are given indicating the relationship between impurity or minor constituent concentration and relative line intensities.—D. M. Smith: The spectrographic assay of some alloys of lead. The method is based on standards of known composition either synthetically prepared or determined by accurate chemical analysis. One of its great practical advantages is that it is very much more rapid than ordinary chemical assay of these metals. Spark spectra are preferred, as giving more consistent results than arc spectra. By simple direct comparison of spectra the constituents can be determined within the range 0.1–1 per cent, with an accuracy of 10 per cent. —John L. Haughton and Ronald J. M.Payne: Transformations in the gold-copper alloys, with an appendix on X-ray examination of gold-copper alloys, by G. D. Preston. By recording autographically the variation of resistance with changing temperature of alloys of composition ranging between 20 per cent and 70 per cent atomic of gold, and by measurements of the specific resistance of alloys slowly cooled to room temperature, the transformations in alloys with compositions in the neighbourhood of those corresponding with the compounds AuCu and AuCu3 have been confirmed, and the presence of another transformation in alloys approximating to the concentration of compound Au2Cu3 has been established.—N. S. Kurnakow and N. W. Ageew: Physico-chemical study of the gold-copper solid solutions. Both annealed and quenched alloys were studied. The existence of the compounds AuCu and AuCu3 has been confirmed by constructing isothermal diagrams of the electrical resistance, and the limits of the solid solutions have been indicated.—M. Cook and E. C. Larke: Physical testing of copper and copper-rich alloys in the form of thin strip. Consistent results for tensile strength and elongation are obtainable on all the materials down to and including 0.02 in. thickness. One of the most satisfying methods of measuring hardness is the diamond pyramid static indentation method. Cupping machines, although they may measure some kind of ductility and, if properly correlated, may afford a good sound indication of the behaviour of a material for cupping and drawing operations, are limited in respect of specification.