bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reinforced Sheets for Load Envelopes Which Combine Tension and Shear
Authors: Harris G. Z. 
Published: July 2016

SummaryAn exact analysis is made of reinforced sheets having three fibre directions using netting analysis. Load envelopes of shear combined with both uniaxial and biaxial tension are assumed and optimum fibre arrangements are determined on the assumption that limits exist on the compressive and tensile forces which may be developed in a fibre. Such optimum fibre arrangements are compared with the best-arranged isotropic reinforced sheets and with hypothetical solid sheets having the same properties as the fibres. Elastic constants are derived for the optimum systems. The total allowable load envelopes of the optimum arrangements are found and are related to the prescribed load envelopes.
Natural Frequencies of Long Tapered Cantilevers
Authors: Carnegie W. , Thomas J. 
Published: July 2016

SummaryThe effect of depth taper on the flexural vibration characteristics of a beam of uniform width is investigated in this paper. The frequency parameters and mode shapes for the first five modes of vibration of tapered beams are presented for a wide range of depth taper. The Euler-Bernoulli equation of a beam is reduced to an eigenvalue problem and its eigenvalues and eigenvectors are obtained by using a digital computer. The theoretical results are compared with those of other authors and with the experimental results.
The Stresses Around Holes in Plane Sheets
Authors: Howard I. C. , Morley L. S. D. 
Published: July 2016

SummaryThis paper describes the application of a previously published variational method to the solution of problems of holes in plane elastic sheets and is used to obtain numerical values for the specific case of an elliptic hole in an infinite sheet under tension at infinity. Two kinds of boundary condition at the hole are discussed. The first is that when the hole is unreinforced and stress free, and the second that when the hole is uniformly reinforced by a compact member. The results of the calculations are compared with those from known solutions to the problem, and the accuracy of the present method is investigated. These results provide a useful background to wider application of the method.
Buckling of a Long Flat Panel with a Series of Equidistant Longitudinal Supports in Combined Longitudinal Compression and Shear
Authors: Wittrick W. H. , Curzon P. L. V. 
Published: July 2016

SummaryThe main purpose of this paper is to illustrate the use of the stability functions for long plates in combined compression and shear defined in a previous paper by the authors. The panel is supported on its two edges and on a series ofNintermediate simple supports. Each of the two edges is either clamped or simply-supported and numerical results are given for each of the three possible combinations, with varying numbers of supports. In all cases it is found that a simple parabolic interaction formula between shear and compression is extremely accurate. Also simple approximate formulae are given for calculating the wavelength of the buckle and the lead of the nodal lines for any combination of compression, shear, edge conditions and number of supports.
The Turbulent Wall Jet in an Arbitrary Pressure Gradient
Authors: Gartshore I. S. , Newman B. G. 
Published: July 2016

SummaryA method for calculating the growth of a turbulent wall jet in streaming flow has been developed. The flow is assumed to be two-dimensional, incompressible and over a plane, smooth wall. Downstream variations of pressure are permitted and separation in an adverse pressure gradient may be predicted. The method incorporates procedures for matching the flow to that at the blowing slot, although it is postulated that the upstream boundary layer there is thin enough that the wall jet develops without an unmixed wake (i.e. there is not a minimum in the mean-velocity profile).The method incorporates four integral momentum equations taken from the wall to various points in the flow. The calculation of the outer shearing stress, although empirical, is based on the large-eddy equilibrium hypothesis and therefore has some foundation. The remaining empiricism in the method is based on measurements in self-preserving wall jets.The method has been used to predict the jet-momentum coefficient required to suppress separation over a trailing-edge flap attached to a thin aerofoil. Plausible curves have been obtained Using assumed values of upstream boundary layer at the slot. Of some practical interest is the indication that large savings in power are possible if the upstream boundary layer is removed. This indicates that blowing combined with upstream suction, or multiple-slot blowing, may give useful savings in the application of blowing to prevent separation.
A Bending Theory for Multi-layer Anisotropic Conical Shells
Authors: Liaw Boen-Dar 
Published: July 2016

SummaryThe governing equations for bending of truncated conical shells with multi-layer anisotropic construction are developed by a variational method. The shell is considered to consist of an arbitrary number of alternating soft and hard layers. It is assumed further that the n hard membrane layers are isotropic and may possess different elastic properties, while the (n-1) soft core layers are orthotropic in general and may take transverse shear only. The variations of stresses across the membranes are neglected, as are the surface-parallel stresses in the cores. These assumptions are consistent with those usually employed in single-core sandwich shells. The energy functional is formulated with the stresses considered as independent variables. The stresses are also dependent variables defined in the set of two curvilinear co-ordinates defining the surface of the shell. The stress resultants are introduced as constraint conditions utilising Lagrange multipliers. Successful definition of an elastic neutral surface ensures the uniqueness of shell constants and the equations obtained may be in a form comparable to that of classical shell theory. The system of equations is reduced to a form where Galerkin’s method can be applied directly.
The Calculation of the Three-Dimensional Turbulent Boundary Layer: Part III. Comparison of Attachment-Line Calculations with Experiment
Authors: Cumpsty N. A. , Head M. R. 
Published: July 2016

SummaryWind tunnel measurements have been made of the attachment-line boundary layer on a swept wing. The combination of a 4-5 in (114 mm) nose radius and 60° angle of sweep enabled a wide range of values of the parameter V2/(v dU/dx) (denoted here by C*), to be covered, and gave a thick enough boundary layer for the velocity profiles to be accurately measured. Pitot traverses were performed for values of C* from 0·59 × 105 to 3·7 × 105. Without a trip wire fitted the attachment-line flow was laminar over the full range and the measured velocity profiles agreed closely with the theory for an infinite swept wing. With a large trip wire fitted, a transition régime was observed in the range 0·6 × 105 < C* < 1·4 × 105, and at higher values of C* the flow was fully turbulent and showed good agreement with the earlier calculations of Cumpsty and Head. Preston tubes were used for skin friction measurements in fully turbulent conditions and a hot wire was used to explore the development of turbulence in the transition régime.
Vibrations of Tapered Cantilever Beams and Shafts
Authors: Murty A. V. Krishna , Prabhakaran K. R. 
Published: July 2016

SummaryVibration characteristics of a linearly tapered cantilever beam and a shaft have been studied by using the lumped inertia force method; a linear displacement distribution is considered over each element. The results are compared with some of those in the literature and with experimental observations. These comparisons indicate that, even using a few elements, a reasonable degree of accuracy can be obtained in the natural frequency, although it is essential to consider more elements in order to determine mode shape accurately.
An Improved Reversed-Flow Formulation of the Galerkin-Kantorovich-Dorodnitsyn Multi-Moment Integral Method
Authors: Bethel Howard E. 
Published: July 2016

SummaryAn improved reversed-flow formulation of the Galerkin-Kantorovich-Dorodnitsyn multi-moment integral method is presented in this paper. Convergence and accuracy properties of the approximate solutions of the Stewartson lower branch similar flows are given. The approximate solutions obtained with the new formulation for the lower branch similar flows are, in general, more accurate than those obtained with the classical Pohlhausen method or either of the previous formulations used with the GKD method.
Effect of a Continuous Area Convergence on the Motion of a Shock Wave
Authors: Wilcox P. L. 
Published: July 2016

SummaryThe transient motion of a shock wave is investigated during its passage through ducts containing various area convergences. The method of characteristics has been used to follow the unsteady motion of the shock wave in an inviscid, non-conducting gas. The strength of the shock is taken to be large enough so that initially both sets of characteristics face downstream. The results are found to be in good agreement with unsteady and quasi-steady theories. A comparison is made between the characteristics results and experimental results obtained in a 1 ft (0·305 m) diameter shock tube. This shock tube incorporates a 3·75:1 linear area change in the low pressure section length. Good agreement is found between experiment and theory. A comparison is also made with other experimental work.
Reduction of Base Drag by Boat-Tailed Afterbodies in Low-Speed Flow
Authors: Mair W. A. 
Published: July 2016

SummaryDrag measurements were made on a blunt-based body of revolution with the addition of several alternative boat-tailed afterbodies. The best of these afterbodies, with a length of only 60 per cent of the maximum diameter, gave almost as much reduction of drag as a conventional streamline tail. The pressure distribution on this body was measured for various lengths. It does not seem to be possible at present to predict quantitatively the drag of this type of body but some qualitative design principles have been suggested.
Simplification of the Razor Blade Technique and its Application to the Measurement of Wall-Shear Stress in Wall-Jet Flows
Authors: Pai B. R. , Whitelaw J. H. 
Published: July 2016

SummaryExperiments in a in (6-35 mm) channel have yielded further information on the precision and convenience of the razor blade technique. It is shown that adhesive tape or carefully located cement can be used to secure a segment of razor blade over a static pressure hole: the resulting calibration for shear stress remains valid if the blade is removed and relocated over the same or a different, similar sized hole. Razor blade segments, calibrated in this manner, have been used to measure wall-shear stress in a turbulent boundary layer with tangential, secondary injection: the results indicate that V. C. Patel’s law of the wall is valid for such flows.
Some Extensions of Thin-Shock-Layer Theory
Authors: Squire L C 
Published: July 2016

SummaryIn the usual form of thin-shock-layer theory it is assumed that the flow about a lifting body can be expanded in terms of the inverse density ratio across a basic oblique shock wave lying in the plane of the leading edges of the body. In this paper it is shown that more accurate results can be obtained by moving the basic shock closer to the calculated shock wave below the body. The results obtained show why the original form of thin-shock-layer theory often gave good agreement with experiment in conditions which appeared to be outside the range of validity of the theory.
Non-Linear Vibration Analysis of a Rectangular Plate on a Viscoelastic Foundation
Authors: Kishor B , Rao J S 
Published: July 2016

SummaryAn analysis is presented for the non-linear vibrations of an elastic rectangular plate resting on a viscoelastic foundation. Hamilton’s principle is used for obtaining coupled non-linear partial differential equations of the system. These equations are uncoupled with the help of Berger’s approximation and the Galerkin method is used to obtain the solution of the resulting equations. Particular cases of the plates on an elastic foundation are also discussed.
Effects of Yaw on a Gothic Wing at Supersonic Speeds
Authors: Narayan K Yegna 
Published: July 2016

SummaryResults are presented of an experimental study of the pressures on the flat windward surface of a Gothic wing at a free-stream Mach number of 3.5 and at moderately high angles of attack, including the effects of yaw. The results show that the perturbation in pressure due to yaw is almost independent of the streamwise distance from the vertex. As a result, it has been possible to calculate the pressure distribution on the yawed wing using the appropriate yawed conical wing results, the zero yaw results being calculated by the “equivalent” delta wing method. The calculations show reasonable agreement with the experiments and confirm that the perturbation due to yaw generates a stabilising rolling moment.
Extensional Effects in Constrained Viscoelastic Layer Damping
Authors: Nakra B C , Grootenhuis P 
Published: July 2016

SummaryThe vibration damping in unsymmetrical, multi-layer beams is obtained by the combined effects of extensional and shear stresses in the viscoelastic layer. The shear stress distribution is not constant across such a layer, although previous work has ignored this. The error in an estimate based on the previous work of the overall loss factor can be large, in particular for the lower resonant modes of long beams with a stiff damping layer.
Governing Equations for Thick Sandwich Shells with Honeycomb Cores and Laminated Faces
Authors: Webber J P H 
Published: July 2016

SummaryThe governing elasticity equations for sandwich shells of double curvature are discussed. No restriction is placed on the thickness of the honeycomb core, and the faces are taken to be made up from fibre reinforced plastic laminations. Some numerical results are given for a circular cylinder subjected to uniform internal radial loading. The results show the importance of treating the core as a thick shell, and of including the bending effects and coupling terms in the laminated faces.
Rotational Cut-Off and Anharmonicity Effects on Thermodynamic Properties of Gases at High Temperatures
Authors: Reddy N M 
Published: July 2016

SummaryThe exact expressions for the partition function Q and the coefficient of specific heat at constant volume Cv for a rotating-anharmonic oscillator molecule, including coupling and rotational cut-off, have been formulated and values of Q and Cv have been computed in the temperature range of 100°K to 100 000°K for O2, N2 and H2 gases. The exact Q and Cv values are also compared with the corresponding rigid-rotator harmonic-oscillator (infinite rotational and vibrational levels) and rigidrotator anharmonic-oscillator (infinite rotational levels) values. The rigid-rotator harmonic-oscillator approximation can be accepted for temperatures up to about 5000°K for O2 and N2. Beyond these temperatures the error in Cv will be significant, owing to anharmonicity and rotational cut-off effects. For H2, the rigid-rotator harmonic-oscillator approximation becomes unacceptable even for temperatures as low as 2000°K.
Similarities in Pressure Distribution in Separated Flow Behind Backward-Facing Steps
Authors: Badri Narayanan M A , Khadgi Y N , Viswanath P R 
Published: July 2016

SummaryStatic pressures have been measured in the separated flow region behind backward-facing steps in a wind tunnel, suitable corrections being applied for the model blockage. The results indicate a reasonably well defined similarity in the pressure distribution.
Experiment on Turbulent Boundary Layers on a Concave Wall
Authors: M C So Ronald , Mellor George L 
Published: July 2016

SummaryThe present experiment describes the behaviour of a turbulent boundary layer on a concave wall. At the onset of curvature there appears a fairly coherent wavelike transverse profile of mean velocity. This disturbance might be interpreted as a kind of large scale Taylor-Görtler type instability superimposed on a conventional turbulent boundary layer; further downstream the coherence degenerates as the turbulence level increases. Boundary-layer profile measurements were made at positions of maxima and minima of transverse profiles of (U-component) mean velocity. The boundary layer at the minima positions is found to be twice as thick as that at the maxima positions. Also, turbulent intensities inside the boundary layer are substantially increased as a result of the concave curvature of the surface.
Calculation of a Turbulent Boundary Layer Downstream of a Small Step Change in Surface Roughness
Authors: Antonia R A , Wood D H 
Published: July 2016

SummaryMeasurements of mean velocity and Reynolds shear stress have been made in a turbulent boundary layer downstream of a small step change in surface roughness. Upstream of the step the surface is smooth, while downstream it consists of a d-type rough wall made up by a series of two-dimensional elements of square cross section placed transversely across the flow and spaced one element width apart in the direction of the flow. The calculated mean velocity and Reynolds shear stress profiles obtained using the method of Bradshaw, Ferriss and Atwell are in good agreement with the measurements throughout the relaxation region of the layer. Well downstream the calculation method adequately reproduces the self-preserving features of a d-type rough wall.
Vibration and Buckling of Cross-Ply Laminated Circular Cylindrical Panels
Authors: Sinha P K , Rath A K 
Published: July 2016

SummaryThe paper deals with the free transverse vibration and stability analysis of circular cylindrical composite panels. The panels are assumed to be composed of an arbitrary sequence of 0° and 90° layers. The non-dimensional vibration and buckling parameters are computed for simply-supported panels consisting of antisymmetric crossply graphite-epoxy laminates. The influence of the coupling between bending and extension, shear deformation, the panel curvature, and the aspect ratio are then discussed.
Eddy Viscosity and Entrainment in Equilibrium Boundary Layers
Authors: Head M R , Galbraith R A McD 
Published: July 2016

SummaryThe properties of equilibrium turbulent boundary layers have been examined using Thompson’s family of velocity profiles along with alternative π – G relationships. The relationship which is in best agreement with measurements of equilibrium layers confirms an earlier suggestion that (νT/Uδ*)max is not a universal constant for such layers but decreases for small and negative values of π. A close relationship is established between eddy viscosity and entrainment, and it is shown that veδ/νT is effectively constant for π > 2.
Buckling and Post-buckling Behaviour of Plates with Holes
Authors: Ritchie D , Rhodes J 
Published: July 2016

SummaryThis paper gives details of theoretical and experimental investigations into the behaviour of simply-supported uniformly compressed square and rectangular plates with central circular holes. The theoretical analysis employs an approximate approach using a combination of Rayleigh-Ritz and finite-element methods. The experimental investigation consisted of a number of experiments on plates with hole diameters from one- to seven-tenths of the plate width. Agreement between experiment and theory is shown to be good at buckling. In the post-buckling range it is found that the theoretical analysis is reasonably accurate for small holes, but loses accuracy when dealing with large holes.
Large Deflection of Axisymmetrically Loaded Spherical Caps
Authors: Chia Chuen-Yuan 
Published: July 2016

SummaryThis study is an investigation of the non-linear behaviour of an elastic spherical cap under the assumption of axisymmetric deformation. The types of axisymmetric loading under consideration are partially loaded uniform pressure, line load, “cosine” load with the maximum intensity at the apex and the combined action of uniform pressure and line load. The edge of the cap is assumed to be rigidly clamped, hinged, and unrestrainedly simply-supported. The method of solution is an extension of the iterative procedure for the integral equations formulated by Budiansky for uniformly loaded, clamped caps. In the cases of hinged and unrestrainedly simply-supported edges, the critical loads for the axisymmetric snap-buckling are presented for different types of loading and various values of the geometrical cap parameter. In the case of a clamped edge the load-deflection curves are established until no solution can be found for further increasing the load. The load corresponding to the limit point on the load-deflection curve is the critical load if the axisymmetric snap-buckling exists. The graphical results are presented for load-deflection curves, deflection profiles, bending moments, transverse shear and interaction of buckling pressures and buckling line loads. The present results are in good agreement with available data for uniform pressure distributed over the entire surface of the cap with three sets of edge conditions and over the central portion of a clamped cap.
Remarks on Unsteady Newtonian Flow Theory
Authors: Mahood G E , Hui W H 
Published: July 2016

SummaryUnsteady high Mach number flows past oscillating cones and oscillating wedges are studied according to Newtonian impact theory, with and without centrifugal force corrections. It is found that, contrary to existing theories, the centrifugal force contribution in unsteady flow is significant and not negligible; for example, it contributes one-half to the dynamic stability derivatives of an oscillating wedge and one-third to that of an oscillating cone. It is also shown that in both cases the dynamic stability derivatives calculated by Newtonian impact theory with centrifugal force correction agree exactly with those obtained by gas-dynamic theory in the double limit γ → 1 and M∞ → ∞, independently. These conclusions are expected to hold for more general three-dimensional unsteady Newtonian flow when the Newtonian shock layer is attached.
Supersonic Turbulent Boundary Layers: Some Comparisons Between Experiment and a Simple Theory
Authors: Stollery J L 
Published: July 2016

SummaryComparisons are made between some measurements of skin friction and heat transfer over five axisymmetric bodies and the predictions of a simple theory. The development of the theory is outlined and explicit expressions obtained for all the gross turbulent boundary-layer characteristics (δ*,θ,H,Cf and St).
Golf Ball Aerodynamics
Authors: Bearman P W , Harvey J K 
Published: July 2016

SummaryA wind tunnel technique has been developed to measure the aerodynamic forces acting on golf balls over a wide range of Reynolds number and spin rate. Balls with round dimples and hexagonal dimples have been investigated. The dimples are found to induce a critical Reynolds number behaviour at a lower value of Reynolds number than that experienced by a smooth sphere and beyond this point, unlike the behaviour of a sand-roughened sphere, there is little dependence of the forces on further increases in Reynolds number. A hexagonally-dimpled ball has a higher lift coefficient and a slightly lower drag coefficient than a conventional round-dimpled ball. Trajectories are calculated using the aerodynamic data and the ranges are compared with data obtained from a driving machine on a golf course.
General Solution of the Problem of Large Deflection of an Annular Membrane under Pressure
Authors: Na T Y , Kurajian G M , Chiou J P 
Published: July 2016

SummaryThe non-linear boundary-value problem resulting from an analysis of the stresses and deflections of an annular membrane is transformed into an initial-value problem, replacing the iterative and series methods of Pifko and Goldberg. A general solution valid for the complete range of values of the ratio of inner and outer radii is obtained and tabulated by this non-iterative method.