Transverse Edge Research Articles

Analysis of transverse edge effect of linear induction pump with electrically conducting side walls.

An analytical study is made of transverse edge effect on the flow characteristics and performance of a linear induction pump by taking into account both effects of a nonuniform velocity distribution across the duct width and an electrical conductivity of the side-walls installed in a fringing magnetic flux region.Equation of fluid motion and Maxwell's equations with a thin-plate approximation are simultaneously solved using a method of successive approximation, and the effects of the side-wall's conductivity on the distributions of magnetic field and flow velocity are deter-mined. Pump performances such as mechanical and electrical powers, conversion efficiency and head-flow curves are also obtained.It is clearly shown that the secondary current in the fluid and hence the pump per-formance are significantly influenced by the side-wall's conductivity. It is also shown that the nonuniformity of the velocity distribution causes a reduction in the equivalent conduc-tivity of the secondary which is significant in the case of low side-wall's conductivity.

Edge Effects in Uniaxial Compression Testing of Cross-Ply Carbon-Fiber Laminates

Experimental data from static uniaxial compression tests of cross-ply laminates of two thicknesses and two stacking sequences are presented and compared with theoretical predictions from a non-linear laminated plate analysis and with numerical results from a free-edge solution. The ex perimental data shows the existence of an edge effect in the laminates similar to that predicted theoretically, and which depends upon the laminate stacking sequence and thickness. No evidence was found of transverse cracking or edge delamination prior to total laminate failure.

Calculation of transverse edge effects of linear induction motor using Fourier's series method

A single sided linear induction motor with a finite width of the primary is considered. Calculations of magnetic flux density, currents, forces and power losses have been performed for two layers of a secondary using Fourier's series method. Conducting plate thickness and currents in the secondary back iron have been taken into account in an idealized LIM model. Obtained computational results have been compared with the experimental measurements.

Analytic Solution for Continuous Sandwich Plates

An analytical solution is presented for simply supported continuous sandwich plate over two spans and subjected to transverse loads. The process involves utilizing the force method in conjunction with the principle of superposition. Solutions for simply supported single sandwich plates subjected to transverse loads and edge moments are found first, and then combined to ensure deformation compatibility along the middle support. The effects of transverse shear deformations on the response of continuous plates are found to be substantial, unlike the case of simply supported single plate. Simple expressions are derived for uniform distributed and concentrated loads.

Distribution, Movement and Abundance of Polar Bears in Lancaster Sound, Northwest Territories

Mark-recapture studies show that polar bears are distributed at varying densities throughout Lancaster Sound during winter and spring. Major concentrations occur along the north and south coasts and the transverse floe edge at the mouth of the sound. As the ice melts, some bears move west whereas others move to nearby land areas. There is some evidence that as the ice forms, polar bears return from their summer locations to eastern Lancaster Sound. Polar bears of Lancaster Sound are part of the larger population whose western range extends to Barrow Strait, Prince Regent Inlet, Wellington Channel and Jones Sound. The southern and eastern range limits are unknown although this population may extend at least to Clyde River on northeastern Baffin Island and probably to Greenland. Maternity denning appears to be widespread over the study area probably because of the abundance of suitable habitat. We estimated a population of 1031 ± 236 polar bears in Lancaster Sound during 1979: however, more estimates are needed to determine if this relatively high number is normal for the area.Key words: polar bear, distribution, movement, abundance, Baffin Bay, Lancaster Sound, summer retreat, denning

Boundary integral equation solution of the single sided linear induction pump problem

This paper utilizes the Boundary Integral Equation Method to analyse the single sided linear induction pump. The advantage offered by the method is that transverse edge effects are not neglected. The equations necessary for the electromagnetic field and force analysis of the pump are developed and the numerical solution of the equations is described. Particular attention is given to means of calculating the electromagnetic fields within the molten metal secondary. Typical field and force distributions are presented.

Initiation and growth of transverse cracks and edge delamination in composite laminates. Part 1 An energy method

Initiation and growth of transverse cracks and edge delamination in composite laminates. Part 1 An energy method

Initiation and growth of transverse cracks and edge delamination in composite laminates. Part 2 Experimental correlation

Initiation and growth of transverse cracks and edge delamination in composite laminates. Part 2 Experimental correlation

A generalised effective width method for plates loaded in compression

Abstract In recent years there have been a number of notable theoretical studies which have provided extensive load-shortening curves for rectangular plates loaded in compression along their transverse edges. These studies have provided engineers with a clear understanding of the effects which initial out-of-plane deformations and residual stresses have upon the behaviour of plates loaded in compression. The present paper shows how the information provided by these load-shortening curves can be utilised to provide effective width expressions. This will enable this latest research information to be incorporated in those existing design methods which utilise an effective width approach. One important benefit of the present study is that whereas earlier effective width formulae only provided information on the load-carrying capacity of a plate up to its peak load, the proposed method enables the post peak load behaviour of a compressed plate to be readily calculated.

Fracture criteria in cracked bimaterial elastic plates

A plane bimaterial model is introduced which allows the determination of the stress intensity factors KI and KII, as well as the fracture angle theta 0. The model is composed of a long orthogonal strip penetrating into an elastic orthogonal soft matrix. The strip is cemented along three of its edges with the matrix and the composite is submitted to either symmetric tension, or compression. Simple tension of the model creates slowly progressing cracks in the matrix parallel to the transverse edge of the strip, whereas compression develops slowly growing oblique cracks at different angles to the transverse edge of the strip. For the evaluation of the components of the complex stress intensity factor, the optical method of reflected caustics is used. The orientation of both external and internal caustics yield also the fracture angle theta 0. A significant advantage of the model is that the developed cracks in the matrix may grow slowly at any desired velocity. So it is possible to study the stress field near the propagating crack-tip without using expensive optical and electronic equipment. The results derived by testing different composites are examined according to the two main fracture criteria and useful conclusions are obtained.

Initiation and Growth of Transverse Cracks and Edge Delamination in Composite Laminates Part 2. Experimental Correlation

In part one of this paper, the fracture processes of multiple transverse cracking and free edge delamination in composite laminates have been analyzed by an energy method. Numerical analyses and experimental examination using a series of T300/934 graphite epoxy laminates are pre sented in this part two. While part one is presented in a self-contained form, part two must be regarded as the continuation of part one.

Initiation and Growth of Transverse Cracks and Edge Delamination in Composite Laminates Part 1. An Energy Method

This paper is concerned with the basic fracture mechanisms involved in matrix-dominated failures in fibrous composite laminates, Specifically, interlaminar fracture in the form of free-edge ply delamination and intra- laminar fracture in the form of multiple transverse cracks are investigated. In each case, a theory is formulated based on the classical linear fracture mechanics concept of strain energy release rate as a criterion for crack growth. A finite element technique incorporating the virtual crack-closure procedure is developed to generate numerical results. Simultaneously, an experimental study is conducted using a series of graphite epoxy laminates in the form of (±25/90 n) s, n = 1,2,3. Part 1 of this paper presents the development of the method from the conceptual, physical and numerical considerations, while Part 2 provides for a comparison between the analyti cal and experimental results.

Attenuating the Transverse Edge Effect in MHD Generators

HE longitudinal edge effect associated with a sharp drop in the magnetic field when entering and leaving the channel of an MHD generator results in the formation of closed current loops (Fig. la), which reduce the net generator output, increase Joule losses, and reduce the generator efficiency. It was suggested by Sutton 1 that the longitudinal edge effect be attenuated by placing nonconducting partitions at the inlet and exit of the electrode zone. A specific inhomogeneity of the electric current, the socalled * 'transverse edge effect, also arises in the channel cross section when, as a result of nonuniformity of the velocity in the direction of the magnetic field, a part of the current forms a closed loop over the boundary layers near nonconducting walls (Fig. Ib). We suggest in this study that nonconducting baffles, parallel to the magnetic field and adjoining the insulated walls, be placed in the electrode region of the generator. By analogy with the partitions employed by Sutton, 1 such a placement of baffles just will attenuate the shunting currents flowing along boundary layers at the insulated walls of the channel (Fig. Ib).

Stress-wave detection of an edge crack in an elastic rod

Mechanical stress wave propagation in a long, thin, isotropic, elastic rod containing a single transverse edge crack is studied theoretically and experimentally. It is found that one-dimensional wave theories, coupled with an effective “compliance” of the cracked region, predict reasonably well the observed dynamic strains induced by a longitudinal impact. Remote sensing of relatively deep cracks appears feasible and consequently the procedure may be useful clinically for determining the rate of healing of partially cracked bone.

Stresses in a semi infinite strip

Results for a semi-infinite strip subjected to general non-symmetrical loadings along all the three edges are given in this paper. On satisfying boundary conditions an infinite system of linear algebraic equations is obtained. The infinite system can be solved either by the method of reduction or by the method of successive approximations. The applicability of method of reduction and aspects of convergence and bounds for unknowns in the method of successive approximations are discussed. The loadings on the transverse and longitudinal edges cannot be arbitrary and the permissible loadings have been discussed.

Free Flexural Vibrations of an Elliptical Plate with Edge Restrained Elastically

It is the object of this paper to make clear the free flexural vibration characteristics of an elliptical plate with the edge restrained in a manner that prevents transverse edge motion and provides a restoring edge moment proportional to rotational angle of edge. Based on the ordinary thin plate theory, the procedure leading to a frequency equation is given in the case of the normal mode of symmetrical vibration about both axes. The numerical calculations are carried out and the lowest nondimensional frequencies are tabulated for he aspect ratios of the ellipse and the rotational spring stiffnesses of edge restraint in the cases of Poisson's damental ellipse tends to a circle, the frequency equation degenerates to the form for a circular plate.

Optimum goodness criterion for linear-induction-motor design

Linear induction motors (l.i.ms) have many possible applications, ranging from low-speed cranes to high-speed ground-vehicle propulsion. However, in average and high-speed l.i.ms, the end effects cause considerable deterioration in the performance in low-slip regions. The paper introduces the concept of realistic goodness factor GR, which takes into account by appropriate coefficients the airgap leakage, secondary sheet skin effect and transverse edge effects. Approximations involved in obtaining GR are discussed and essentially a one-dimensional analysis is used. It is shown that the end-effect influence can be expressed as a function of GR, slip and the number of poles. An optimum goodness-factor criterion Go to aid an optimum l.i.m. design is proposed. It is demonstrated that Go can be achieved in practice, and leads to a good-performance, low-weight l.i.m. Numerical results based on a full-size existing l.i.m. test vehicle are given.

Simulation of high-speed linear-induction-motor end effects in low-speed tests

The paper presents two new possibilities of simulating end effects and transverse edge effects of a high-speed linear induction motor in a rather low-speed test if certain equivalence conditions are satisfied. The basis of simulation is to keep the flux-density distribution in the airgap, as well as in the exit and entry zones, the same in the simulated l.i.m. as in the actual l.i.m. It is demonstrated that a realistic simulation may be obtained in practice. Two examples are given which show the parameter values to simulate a fullsize high-speed l.i.m. by (a) a low-speed l.i.m. and (b) an arch motor.

Calculation of plane electric fields in channels of magnetohydrodynamic instruments

The local and integral characteristics of flat MHD channels are studied with allowance for longitudinal and transverse edge effects and heterogeneities in the distributions of conductivity and stream velocity. An analysis is made of the effect of the finite dimensions of the insulating inserts in the longitudinal edge effect and of the modular construction of the side wall in the transverse edge effect on the output parameters of MHD channels. The solution of the problem is based on reduction of the initial quasilinear elliptical equation for the electrical potential with allowance for Ohm's law to an integral equation of the Fredholm type relative to the current density.

Tidlig neolitiske anlæg ved Tolstrup

Tidlig neolitiske anlæg ved Tolstrup