Showing papers on "Deflection (engineering) published in 1974"

Time-dependent reinforced concrete slab deflections

Abstract: A finite element analysis to determine time-dependent deflections of reinforced concrete slabs, including the effects of cracking, creep, and shrinkage, is presented. The analysis employs a 16-degree-of-freedom layered rectangular plate bending element, and uses a numerical time integration scheme to evaluate creep and shrinkage strains determined from CEB parameters. The initial strain technique is used in the solution procedure. Predicted results are compared with the limited experimental results in the literature.

Layered Beam Analysis

Abstract: Governing equations for layered Timoshenko beam theory for the general case of unsymmetrically stacked laminated beams are presented. A computer program is developed to use the theory to investigate layered beam problems with any kind of end conditions and any transverse loading. Capability is also demonstrated for varying properties such as modulus of elasticity along the length of the beam. The method is applied to the study of laminated wooden beams. Variations of deflection, shear stress, and normal stress with percentage of strong wood along the outer fibers is shown. The program is not meant to be a design tool. The main purpose of the program is to furnish an analytical tool to use in correlating experimental data with theoretical results so that assumptions regarding physical properties can be altered if need be. A study of the effect of changing the properties of a wooden laminated beam is presented.

Minimum Weight Sandwich Beam Design

Abstract: thin compared with the core, ie, f/c<^ 1 The faces resist the longitudinal loads and the core resists the transverse load It is assumed that the shear stress in the core is constant across its depth The governing equations for sandwich beams can be written in terms of partial deflections wb and ws wb is the deflection of the sandwich beam due to bending only, it occurs if Gc, the shear modulus of the core, is infinite ws is the deflection of the sandwich beam due to shear deformation of its core, it occurs if £/, the Young's modulus of the face, is infinite Huang2 presents a detailed development of partial deflections The total deflection w is the sum of partial deflections wb and ws

An Evaluation of Stresses and Deflection of Spur Gear Teeth Under Strain

Abstract: This paper aims at an evaluation of the stresses induced by a static load applied to gear teeth. For spur gears of different ratios with 20-deg pressure angle and standard addendum proportions, the stresses and deflections are computed by the finite element method. Formulas are drawn allowing a simple calculation of the maximum stresses, and the results are compared with what is given by ISO and AGMA standards related to the strength of gear teeth.

Light beam scanning and deflection in epitaxial LiNbO3 electro‐optic waveguides

Abstract: We report a method of scanning and deflecting a light beam in an electro‐optic waveguide of epitaxial LiNbO3 film. The method involves the use of the electro‐optic effect for excitation of a proper distribution of the refractive index which causes the light beam to deflect. The angle of deflection is found to vary continuously with the intensity of the applied field. We are able to scan a light beam in the plane of the film up to 4°. We also present a theory for the light beam deflection and show that our method does optimize the deflection efficiency.

Nonlinear buckled states of rectangular plates

Abstract: A constructive method is developed to establish the existence of buckled states of a thin, flat elastic plate that is rectangular in shape, simply supported along its edges, and subjected to a constant compressive thrust applied normal to its two short edges. Under the assumption that the stress function and the deformation of the plate are described by the nonlinear von Karman equations, the approach used yields information regarding not only the number of buckled states near an eigenvalue of the linearized problem, but also the continuous dependence of such states on the load parameter and the possible selection of that buckled state “preferred” by the plate. In particular, the methods used provide a rigorous approach to studying the existence of buckled states near the first eigenvalue of the linearized problem (that is, near the “buckling load”) even when the first eigenvalue is not simple.

Electro‐optically induced deflection in liquid‐crystal waveguides

Abstract: This paper describes electro‐optically induced tunable deflection in the plane of a waveguide structure by utilizing the liquid‐crystal property of tunable birefringence together with appropriately designed electrodes. The magnitude of tunable deflection achieved in this experiment (>20°) had only been demonstrated in passive structures in the past. Furthermore, by changing the device parameters slightly, electrically controlled total internal reflection or refraction in the plane of the waveguide structure was demonstrated. This allowed operation of the device as a switch where the guided beam was deflected or ``switched'' through a very large angle (>70°) in the plane of the guide.

Unbonded contact between a circular plate and an elastic half-space

Abstract: The paper concerns the unbonded contact between a thin circular plate of finite radius, governed by Kirchhof or Reissner theory, pressed by means of rotationally symmetric distributed load and its own weight against the surface of an elastic half-space. The contact is assumed frictionless and unbonded. A Hankel transform solution is used for the half-space and the plate deflection is found by inverting the plate equation. The coefficients in a power expansion are obtained by equating plate and half-space deflections at a number of points in the contact region. The variation of contact radius with plate radius, the radius of the uniformly applied load, and the relative stiffness of plate and foundation, is displayed in a series of figures.

Character image generation apparatus and CRT phototypesetting system

Abstract: Apparatus for reproducing characters from cathode ray tubes wherein a beam is deflected onto alpha/numeric characters occupying a selected area of a font. The beam is deflected by relatively high speed linear vertical strokes which are displaced horizontally by a slower speed stroke advance waveform and each scan is positioned relative to one of the selected areas. The vertical linear strokes of the beam are at a variable rate and the vertical strokes are terminated by time interval pulses at an amplitude corresponding to the area height of the font character. The rate of the strokes is determined by the time interval pulses which in turn are regulated by point size control selection means. A resultant two level output signal representative of the successive selected characters controls another cathode ray tube, the scanning of which is identical to that of the first cathode ray tube. The deflection of the beam in the second cathode ray tube is at a constant rate and the intervals of the strokes in the scanning of the second cathode ray tube are also controlled by the time interval pulses.

Finite Element Analysis of Slabs on Elastic Solids

Abstract: A finite element method programmed for a high speed computer was developed for analyzing concrete slabs on an elastic continuum. The method differs from conventional in that an iterative scheme is employed. The iterative scheme has the major advantage of reducing the computer storage and can be used for analyzing two slabs with load transfer at the joint. A comparison between the finite element and the analytical solutions indicates that the finite element method is accurate enough for engineering applications. Comparisons of the stresses and deflections obtained by the method with those measured in the Arlington test for various conditions of loading and warping also show good agreements. It was found that the agreement based on full contact between the slab and the subgrade was not as good as that based on the assumption that part of the slab near to the edge is not in contact with the subgrade.

Illustrations of Reliability-Based Design

Abstract: First-order probabilistic selection of safety factors is illustrated with practical examples of design of reinforced concrete beams, structural steel columns, and cold-formed steel beam elements. The example on deflection in concrete beams indicates how performance criteria can be formulated using the proposed design methods. The examples also show that it is possible to reconcile design methods by proper selection of code parameters and to calibrate design in one technology against another.

An Energy Method Applied to Large Elastic Deflection of a Thin Plate of Bimodulus Material

Abstract: Some composite materials and high-polymers are known to behave differently in simple tension and compression under static loads. The present paper is concerned with a method of analysis of the bending of bimodulus elastic plates employing Ambartsumyan-Khachatryan's model for isotropic bimodulus materials. This problem may be reduced to the conventional problem of minimizing the potential energy of the plate as a whole. A simply supported thin square plate subjected to lateral load is analyzed numerically by a simplex method. Results of the calculation show that the effect of the difference between the tensile and compressive elastic moduli on the deformation of the plate may be substantial

Acousto‐optic deflection in Ta2O5 waveguides

Abstract: Surface acoustic waves on quartz have been used for acousto‐optic deflection in Ta2O5 waveguides. Deflection efficiencies for TM modes of up to 93% have been observed with an acoustic power of 175 mW.

Light deflection in multimode waveguides using the acousto‐optic interaction

Abstract: The deflection of light by acoustic surface waves in multimode waveguides is studied in the present work. Conditions on deflection of single‐mode and multimode optical power are derived, and expressions are presented for the number of resolvable spots and the efficiency that may be obtained with these scattering processes. A description of the waveguide analog to anisotropic Bragg scattering is given, and the advantages and disadvantages of this approach are discussed in detail.

Circuit arrangement for generating a sawtooth deflection current through a line deflection coil

Abstract: A circuit arrangement for generating the line deflection current in which the line deflection coil forms part of a network which also includes a diode, a trace capacitor and a retrace capacitor. One or more further similar networks all having the same retrace time are arranged in series and this series arrangement is connected in parallel with a switch which may be that of a combined line deflection and supply voltage stabilizing circuit. The retrace voltage and thus the EHT across this series arrangement can be maintained constant while the line deflection current may be stabilized and/or East-West modulated. A difference current and a North-South correction current may be generated.

Technique for measuring the complex elastic (young{3 s) modulus utilizing laser interferometry

Abstract: The dynamic complex elastic modulus of a viscoelastic material is computed from three longitudinal deflection measurements on a prismatic rod of the material which is subjected to a compressional sinusoidal stress wave. A laser interferometer is proposed to make these deflection measurements in combination with reflecting mirrors which are located at the top, half and quarter positions of the sample rod. The rod is secured at one end and free at the distal end where the compressional stress wave is applied.

Circuit arrangement for generating a deflection current through a coil for vertical deflection in a display tube

Abstract: A field deflection output circuit in which the deflector coil is divided in two halves which are connected between the terminals of a direct-voltage source, in series during the trace interval and in parallel in the retrace interval. As a result the retrace interval may be given the correct duration whilst dissipation is kept low so as to enable the circuit arrangement to be integrated in a semiconductor body.

Measuring rotationally symmetric potential profiles with an electron-beam probe

Abstract: An electron‐beam probe has been developed to measure the potential profile of a plasma within a spherical grid structure which was designed to trap charged particles. The potential was obtained from observed deflections of a collimated beam of electrons incident upon the device at selected impact parameters. The beam consisted of conversion electrons of 62.2 and 84.2 keV from a Cd109 source. Deflections of the beam through the plasma were measured relative to the beam trajectory without voltage applied to the grids. A movable detector allowed angular resolution to within 0.08 deg for maximum deflections of 7 deg. The inversion of the nonlinear singular integral relating potential and deflection is accomplished in an iterative manner with appropriate series expansions about the singular points. Simulations using postulated potential profiles show this procedure to give accuracy typically better than 4% with 20 deflection samples. Beam deflection measurements in spherical electrostatic systems without plasma show this probe technique to be very accurate. For a variety of experimentally controlled plasma parameters, no measurable departures from electrostatic potential profiles were observed.

Apparatus for deflecting light and scanning line conversion system

Abstract: A method and apparatus for deflecting a light beam having high resolution, good linearity with time and high frequency response. For deflecting a light beam, after a monochromatic light beam is applied to a light deflection unit driven by a sinusoidal AC voltage so as to carry out light deflection, the deflected monochromatic light beam is scanned on a deflection angle correction plate which comprises elemental holograms formed by a multiple-beam hologram production technique. Thereafter, the light beam passing through the deflection angle correction plate is focused on a light receiving surface to perform a uniform scanning thereon. An embodiment includes a scanning conversion system for converting a circular scanning line into a linear scanning line comprising a monochromatic light source, a light deflection member for circular-scanning a monochromatic light beam from the monochromatic light source, a deflection angle correction member for forming a deflection light beam through the circular-scanned light beam with this correction member comprising an arrangement of elemental holograms formed by a two-beam hologram production technique and a light receiving member for the diffracted light beam, in which the diffracted light beam from the deflection angle correction member is applied to the light receiving member to carry out uniform linear scanning.

Platform weighing scale

Abstract: A platform weighing scale in which a reinforced load cell-supported platform structure has a framelike reinforcement cooperating with a load-receiving deck or platform to define a torsion box frame which resists load-induced deflection of the platform between spaced apart load cell support points. FIELD OF INVENTION This invention relates to platform weighing scales and is particularly concerned with platform structures which are especially suitably for low profile type platform scales. BACKGROUND Low profile platform scales for weighing relatively heavy loads are characterized by having a relatively small overall height as measured from the floor or other scale-support surface to the top of the load-receiving platform or deck. Scales of this type are especially suitable for weighing loads which are carted by such vehicles as tote bins, push carts, dollies, fork lift trucks and other usually relatively small motor vehicles. Low profile type platform scales normally do not require installation in a pit to accommodate load-carrying vehicles and roll-on loads in general because the platform is relatively close to the floor surface and can easily be accessed by relatively short, gently sloped ramps. Thus, low profile type platform scales offer the significant advantage of pitless installation. On the other hand, in installations where it is desired to locate the platform flush with the floor surface, only a shallow pit is needed. One of the stuctural features which contribute significantly to the floor-to-platform height of prior platform scales is the construction of the platform itself. Typically, the platform in prior scales is a relatively thick structural deck plate which is reinforced by several structural beams on the underside to minimize the deflection or sag of the platform under the influence of loads on the platform. Load-induced deflection of the platform is objectionable in platform scales of the type in which the platform is supported on load cells because the deflection of the platform impairs the accuracy of weight measurements. When the platform deflects or sags under the influence of an applied load the supported corners of the platform curl up to effectively rotate over the load cells. As result, the force transferred by the platform to the load cell rotates away from a vertical line and out of axial alignment with the load cell. This force displacement results in the application of a horizontal force component to the load cell to side load the cell. Since load cells are usually incapable of measuring the horizontal component and since spurious output result from sideloading, the accuracy of the weight-indicating output voltage of the cell will be impaired to extent of the side loading. The customary solution to this problem has been to make the deck plate thick enough and/or to make the deck plate reinforcement strong enough to minimize the deflection of the platform under the influence of applied loads. Such a solution, however, results in platform structures of increased height. It therefore is not compatible with the objective sought in low profile platform scales, namely the minimization of the height of the scale from the support floor to the load-receiving platform surface. Another solution to the platform deflection problem is described in U.S. Pat. No. 3,587,761 which issued on June 28, 1971 to L. C. Merriam et al. This solution however, significantly increases the floor-to-platform height of the scale because it requires a special structure to be interposed between each load cell and the platform to avoid side loading of the cells. The foregoing U.S. patent also illustrates a typical platform structure having a deck plate and reinforcing beams which are seated on the platform-supporting load cells. Other examples of prior weighing scales are shown in U.S. Pat. No. 3,103,984 which issued to C. L. Ellis et al on Sept. 17, 1963, U.S. Pat. No. 2,962,276 which issued to A. L. Thurston on Nov. 29, 1960, U.S. Pat. No. 3,679,011 which issued to I. M. Hawver on July 25, 1972 and U.S. Pat. No. 3,565,196 which issued to E. Laimins on Feb. 23, 1971. SUMMARY & OBJECTS OF INVENTION In the novel platform scale of this invention, the load-receiving platform structure is reinforced in such a manner that it has an extremely low overall height, but yet has a high degree of torsional rigidity to effectively resist load-induced deflection and rotation of the platform in the regions of the platform-supporting load cells without resorting to excessive deck plate thicknesses. Accordingly, a major object of this invention is to provide a novel load cell platform scale in which the load-receiving platform or deck is reinforced in such a manner that it has an extremely low height, but yet affords a high degree of torsional rigidity to effectively resist load-induced deflection and rotation of the deck in the regions of the platform-supporting load cells. Another important object of this invention is to provide a novel scale platform structure which is suitable for low profile platform scale applications and which is reinforced in such a manner to effectively resist deflection under the influence of an applied load. In the illustrated embodiment of this invention, the foregoing objects are achieved by a horizontal framelike reinforcing structure which is positioned vertically below the load-receiving deck to underlie border regions of the deck and which is rigidly joined to the deck by reinforcing structural side members. This reinforcing structure cooperates with the deck to define in vertical cross section a torsion box arrangement which has a closed perimeter. The upper and lower walls of the torsion box are spaced vertically apart and are respectively defined by the deck itself and the framelike reinforcing structure. The sides of the torsion box arrangement are closed by the above mentioned structural side members which are rigidly joined to the deck and to the framelike reinforcing structure. With the foregoing construction, the internal shear flow developed by an applied load will be in opposite directions through the upper and lower walls of the closed box arrangement to create a torsion or twisting couple which resists load-induced deflection or sagging of the deck. In this way, curling and effective rotation of the corners of the deck in the regions of the load cells is resisted to minimize rotation of the load-induced forces which are transferred through the deck and applied to the load cells. The maximum height of reinforced platform structure of this invention is from the bottom face of the framelike reinforcing structure to the upper load-receiving face of the deck. Since the deck and framelike reinforcing plate structure need only be spaced slightly apart to provide a torsion couple moment of sufficient magnitude, the overall height of the reinforced platform structure will be very small. The reinforced platform structure of this invention is therefore particularly suitable for low profile type platform scales. Additionally, the arrangement of the reinforced platform structure with the platform-supporting load cells is such that the upper ends of the load cell force-receiving elements are each at a level which is higher than the lowest surface of the reinforcing structure. With this construction the overall height of the combined assembly of the load cells and the reinforced platform (as measured from the bottom faces of the load cells to the load-receiving deck surface) is less than the sum of the heights of the reinforced platform structure and one of the load cells. With the foregoing in mind, a more specific object of this invention is to provide a novel combined load cell and reinforced load-receiving platform assembly wherein the load-receiving platform or deck is reinforced by a framelike structure which underlies border regions of the platform and which is rigidly joined to the platform by reinforcing structure to defined a box-like arrangement in vertical cross section. Another more specific object of this invention resides in the provision of a combined load cell and reinforced load-receiving platform assembly in which a novel reinforcing structure cooperates with the load-receiving deck or platform to define a torsion box frame in which torsion or twisting couples are developed by an applied load to resist sagging or deflection of the reinforced platform between its load cell support points. Further objects of this invention will appear as the description proceeds in connection with the appended claims and below-described drawings.

Color convergence apparatus for a color television tube

Abstract: The convergence coils of a convergence yoke are provided components of current which are related to currents in a deflection yoke.