Showing papers on "Flexural rigidity published in 1985"

Subsurface loading and estimates of the flexural rigidity of continental lithosphere

Abstract: The flexural rigidity of the lithosphere is often estimated from the linear transfer function (admittance) between gravity anomalies and topography. Admittance estimates strongly weight provinces with large topographic relief, which will tend to be those provinces with low flexural rigidity if the cause of the topography is subsurface variations in density. If the observed admittance of continents is modeled in terms of surface loading of an elastic plate, there is a strong bias toward low flexural rigidities. Models incorporating both surface and subsurface loading yield much higher rigidities. Although the two models may match the observed admittance equally well, only those with both surface and subsurface loading are consistent with the observed pattern of coherence between gravity and topography as a function of wavelength. A new method of analysis shows that surface and subsurface loading are approximately equal in importance in the vicinity of the Kenya rift valley. The flexural rigidity of the East African lithosphere is about 2×1023 N m, or an effective elastic thickness of the plate of 25–30 km. Data from the conterminous United States are consistent with the presence of provinces with a wide range of flexural rigidities, averaging tens of kilometers in effective elastic thickness.

Dependence of the flexural rigidity of the continental lithosphere on rheology and temperature

Abstract: While the first-order mechanical properties of oceanic and continental lithosphere are well defined and explain the observed increase in lithospheric flexural strength with thermal age, the temporal variation of continental flexural rigidity following loading, and its dependence on lithospheric composition and temperature structure, is only just beginning to be appreciated. We describe here the results of a quantitative Theological model in which laboratory-determined rock deformation data and transienttemperature distributions, resulting from intra-plate basin formation within continental interiors, have been integrated. Continental flexural rigidity is shown to be controlled by crustal thickness, lithospheric thickness through the temperature structure, and the interaction of these factors during basin formation. For thermally young lithosphere, the flexural rigidity is dominated by the quartzo-feldspathic theology of the crust, while for the thermally older lithosphere, it is dominated by the olivine rheology of the mantle. Flexural data, through thermo-mechanical models of lithospheric deformation, provide a powerful constraint on both the transient and steady-state temperature structure of the lithosphere.

Isostatic response of the lithosphere with in-plane stress: Application to central Australia

Abstract: The relation between gravity and topography in central Australia cannot be described by a conventional isostatic response function, whether it assumes local or regional compensation or whether the crust behaves as an elastic or viscoelastic medium. In particular, the response function exhibits considerable anisotropy. Hence a theory for isostatic response has been developed for a crust in mechanical equilibrium of surface loads, buoyancy, and in-plane forces and subject to erosion, sedimentation, and stress relaxation. The observed north-south response function exhibits extreme isostatic overcompensation at some wavelengths, and this can be fully explained by the Viscoelastic plate model with in-plane compression. The observed east-west response function is consistent with models of regional or local isostatic compensation. The response function implies an effective flexural rigidity of (5–10)×1022 N m, an effective Maxwell relaxation time of 25–50 m.y., an in-plane compression of 125–150 MPa, and an erosion time constant of about 200 m.y. These parameters assume that the model evolved over a period of about 700 m.y. and are wholly consistent with the evolutionary model developed from geological observations.

A model for the compressive buckling of extended chain polymers

Abstract: A model for the compressive buckling of an extended polymer chain is presented. The application of classical elastic instability analysis to an idealized polymer chain reveals that the bending rigidity and critical buckling loads for a chain are proportional to the force constants for valence bond angle bending and torsion. Highly oriented polymer fibres are treated as a collection of elastic chains that interact laterally. The critical stresses to buckle this collection of chains are calculated following a procedure developed to predict the compressive strengths of fibre-reinforced composites. This buckling stress is predicted to be equal to the shear modulus of the fibres and is the limiting value of compressive strength. Comparison of experimental and predicted values shows that the theory overestimates the compressive strength, but that there is a correlation of shear modulus with axial compressive strength. Consideration of flaws in both the theory and the material indicate that the compressive strength should be proportional to either the shear modulus or shear strength of the fibres.

Ferrule for optical connector

Abstract: A ferrule for an optical connector made of a resin composition comprising a resin and carbon fiber as a filler having larger flexural strength and small mold shrinkage factor. The ferrule has a metal tube around its body that is embedded in its flange portion for added flexural rigidity.

Free vibrations of a gravity-loaded clamped-free beam

Abstract: For the free vibrations of a gravity-loaded clamped-free Euler-Bernoulli-beam (flexible pendulum) no exact analytical solutions are known in the literature. Approximate analytical closed-form solutions are determined by use of the Ritz-Galerkin method with gravity-free beam eigenfunctions in the series expansion. A comparison with experimentally obtained modal data on a heavy beam with strong gravity influence shows good agreement and justifies the necessity of modelling gravity effects. Since in many vibration problems of engineering one of both influences of gravity or flexural rigidity is dominating, further approximated solutions are determined by applying regular perturbation theory (influence of bending moment dominates) and singular perturbation theory by the method of the “matched asymptotic expansions” (influence of gravity dominates: heavy rope with small bending stiffness), which creates a boundary layer problem at the clamped end. Within a wide range of values of the perturbated parameters the lower eigenfrequencies agree well with the Ritz-Galerkin solutions.

Finite Element Methods in Structural Safety Studies

Abstract: The use of finite element methods in structural safety studies is discussed and recent work in the area is briefly reviewed. Formulation for a first-order stochastic finite element method is presented with its application to linear frame structures under static loads. Both structural properties and applied loads are considered to be random. As an example, the reliability of a fixed-end beam with stochastic flexural rigidity and subjected to randomly distributed load is investigated.

Semirigid rod fixation for long-bone fracture.

Abstract: Experiments on 119 New Zealand rabbits were performed to measure healing strength of femurs. Four pairs of normal rabbit femurs were also studied in vitro by use of a four-point bending test to measure bending rigidity. Rabbit-sized octagonal cross-sectioned intramedullary rods with 12%, 20%, 50%, 75%, and 100% of femoral bending rigidity were specially prepared. For each animal, one intramedullary rod was implanted in an osteotomized femur through a standard lateral approach, with the other femur serving as a control. The results from the 12% rigidity rods were widely variable. In the 20% and 50% rigidity groups, the callus diameter was increased over the 75% rigidity group through all phases of healing. The torque ratio in this group increased up to eight weeks and then converged to the ratios of the other rigidities. The 75% rigidity group had shown increase of angular displacement up to eight weeks, while the 20% and 50% rigidity groups continued to improve and reached control strength at 12 weeks of treatment. Furthermore, the 20% and 50% groups absorbed more energy to failure in the later stage of healing than the 75% and 100% rigidity groups. Rods of 20% and 50% rigidity stimulate external callus formation and improve the stability of healing bone.

Effect of anisotropic bending rigidity and finite twisting rigidity on statistical properties of DNA model filaments

Abstract: The persistence length and effective long-range bending rigidity are derived for a discrete model of an anisotropically bending filament and shown to be independent of the torsional rigidity. The twisting persistence length is found to be independent of the anisotropic bending rigidity. Other statistical properties are briefly discussed, including the dependence of tangent vector projections on contour length. The dependence of a tensor contraction on contour length is derived for an isotropically bending filament with no equilibrium twist.

A Model for Fabric Buckling in Shear

Abstract: A mathematical model is presented for the buckling of fabric under combined shear and tensile forces. This model takes account of the anisotropic characteristics of the fabric in terms of the flexural rigidities in the warp and weft directions, its corresponding Poisson's ratios, the shear modulus, and the width to height ratio of the rectangular specimen. Numerical solutions show that the critical shear force at which buckling starts and the number of buckles increase with increasing pre-tension. Furthermore, as the height or width of the rectangular specimen decreases, the critical shear force increases. For most fabrics where the flexural rigidity in the warp direction is higher than that in the weft direction, the results suggest that during tailoring, it is beneficial to orient the fabric so that the tension is in the warp direction to reduce the possibility of shear buckling in the garment.

The Flexural Rigidity of Polyester-fibre–Cotton Yarns Produced on the Ring-, Rotor-, and Friction-spinning Systems

Abstract: (1985). The Flexural Rigidity of Polyester-fibre–Cotton Yarns Produced on the Ring-, Rotor-, and Friction-spinning Systems. The Journal of The Textile Institute: Vol. 76, No. 6, pp. 454-458.

Angular speed/acceleration detector

Abstract: PURPOSE: To simplify a structure and to facilitate processing and assembling, by equalizing the flexural rigidity of the vibration piece of a tuning fork type vibrator in a main vibration direction and that in a detecting direction. CONSTITUTION: An alternating current is made to flow to coils 36a, 36b, 37a, 37b to vibrate vibration pieces 4, 5 and flat plate parts 34, 35 in an X-direction. If the arrangement of magnetic field generating parts 40a, 40b is changed so that line of magnetic induction obliquely traverses the coils 36a, 36b, 37a, 37b, the detection of excitation at least in one direction of both x- and y-directions or the vibration of the flat plate parts at least in one direction of both x- and y-directions can be performed. The cross-sectional shape of each of the vibration pieces 4, 5 is formed in an arbitrary shape almost equalizing flexural rigidity in x- and y-directions in addition to a square shape. Because each of the vibration pieces 4, 5 and the flat plate parts 34, 35 can be manufactured from one silicon monocrystal substrate by two-dimensional cutting processing, manufacturing becomes easy. COPYRIGHT: (C)1987,JPO&Japio

Floating head supporting device

Abstract: PURPOSE:To increase flexural rigidity and torsional rigidity with relatively lightweight constitution, improve the dynamic characteristics of a floating head supporting device, and obtain extremely excellent dynamic characteristics to mechanical oscillation by laminating thin plates into stack leaf spring structure and thus constituting the load spring part of the floating head supporting device CONSTITUTION:A load spring 2a becomes wider at its root part, and a load spring reinforcing plate 2P is coupled with the load spring 2a; and a load spring reinforcing plate 2Q is further coupled with the plate 2P, a load spring reinforcing plate 2R is coupled with the plate 2Q, and the plate thickness of the load spring increases stepwise toward the root part Thus, the plate thickness is small at the tip part and large at the root part, so no increase in the constraint on a gimbals spring 2b due to an increase in rigidity is caused to impede the free motion of the gimbals spring 2b and the rigidity increases as it extends toward the root part by several times as large as when only the load spring 2a is present and obtains on extremely excellent dynamic characteristics having an extremely high natural oscillation frequency at the load spring part

Role of Moisture in the Performance of Sized Yarn

Abstract: Moisture considerably improves the performance of cotton yarn sized with a starch-based sizing recipe. Higher moisture increases yarn elongation but reduces modulus, flexural rigidity, and elastic ...

Method and device for measuring flection characteristic of club shaft

Abstract: PURPOSE:To measure a deflection characteristic of the whole club shaft accurately by placing a flexural load on the club shaft at >=2 points and measuring the fluexural rigidity. CONSTITUTION:The fluexural load is placed on the club shaft 11 in its three sections. When a load placing device 27 closer to the head 12 is put in operation, the load by an identer 27a is placed at distance l1 from a fulcrum 21 to the head 21 until the amount of flection at the operation point attains to a specific valve S1. A load P1 is detected by a load cell 29 and the flexural rigidity is calculated by an arithmetic device 31. Similarly, load placing devices 27 between fulcrums 21 and 22, and fulcrum 22 and the side of a grip 22 are put in operation to calculate the flexural load. Thus, it is known that the club shaft 11 flexes atop, that the center part is soft, or that the part close to the grip flexes, and the composite flexural rigidity value of the whole club shaft is calcuated on the basis of those rigidity values.

Complex screw rotor

Abstract: PURPOSE:To obtain a complex screw rotor having a small thermal expansion coefficient, high bending rigidity, and high fatigue strength by making the shaft part of a screw rotor from the material having a rigidity and strength, and making the toothed part from the material having a low thermal expansion rate and high cutting performance. CONSTITUTION:The shaft part 1 of a screw rotor is made of the iron-basic material containing the ordinary alloy elements having a Young's modulus of 18,000kg/mm or more and a fatigue strength of 45kg/mm after the operations in 5X10 times. A toothed part 2 is made of the low thermal expansion material such as high nickel ductile cast-iron having an average thermal expansion coefficient of 6X10 / deg.C or less at 20-200 deg.C, and said toothed part 2 is joined onto the shaft part 1 through the proper means such as casting joint and shrink-fit, etc.

A comparison between the judgement of specialists and consumers on the hand of pile fabrics

Abstract: The hand of pile fabrics was sensuously evaluated by two panel groups, consumers group and specialists group. The hand terms used for the evaluation by two panel groups were compared, and the relationships between sensory values and physical properties were examined by the use of factor analysis and multiple regression analysis techniques. The results are as follows;(1) Four tactile impressions, namely “softness”, “thickness”, “fullness” and “smoothness”, were commonly chosen to represent the subjective hand of pile fabrics by two panel groups. However, “koshi” and “heaviness” were chosen only by consumers, and “elasticity” and “flexibility” were applied only by specialists.(2) Factor analysis was used to study the relationship between sensory values and physical properties. It is shown that (a) the sensory value referred to the thickness evaluated by consumers and specialists is affected by physical properties of compressive energy, flexural rigidity, frictional coefficient, thickness and weight, (b) the fullness is affected by those of compressive ratio, compressive recovery ratio and compressive modulus, and (c) the smoothness is affected by those of flexural rigidity, frictional coefficient, thickness and weight. The sensory value for the softness evaluated by consumers is simply affected by flexural rigidity and weight, but specialists evaluate it as a combination of compressive energy, flexural rigidity, thickness and weight.(3) As a result of multiple regression analysis, it was found that the common predictor variable of the four sensory values evaluated by consumers is weight and that the sensory values are approximately described by the multiple regression equation of weight and the other physical properties. In case of the specialists, weight is not so useful and a combination of physical properties used for the multiple regression equation is varied by the four sensory values.

Large deflection behavior of quasi-isotropic laminates under low-velocity impact type point loading

Abstract: Eight-ply quasi-isotropic circular composite plates of Thornel 300 graphite in Narmco 5208 epoxy resin (T300/5208) were analyzed to obtain the large deformation behavior under low-velocity impact type point loads. A simple plate-membrane coupling model was developed. The impact type point loads were replaced by equivalent quasi-static point loads. The plate-membrane coupling model was used to obtain the large deformation shapes for the thin circular composite laminates. The analyses indicated that the large deformation shapes of the composite plates under point loads vary with the center point displacements, and hence are different for different load levels. Quasi-isotropic plates were analyzed by replacing anisotropic bending stiffness components with the equivalent flexural stiffness for the isotropic plates. The plate-membrane coupling model was verified by conducting a series of tests on clamped circular quasi-isotropic laminates. Deflected shapes for the thin composite plates were experimentally obtained. These shapes agreed well with the analytically predicted shapes.

Method and device for measuring deflection characteristics of club shaft

Abstract: PURPOSE:To check deflection characteristics of a club shaft accurately by fixing one end side of the club shaft and placing a flexural load on the other end part at least two positions, and measuring flexural rigidity to each flexural load. CONSTITUTION:A flexural characteristic measuring device for the club shaft is equipped with a load applying device 25 which puts the flexural load on the other end part of the club shaft 11 at >=2 specific positions. The example in a figure is equipped with three identers 26, 27, and 28, which are driven by actuators 29, 30, and 31 fixed on the side wall of a casing 23 to move to and away from the top surface of the club shaft 11, and the respective identers 26-28 are lowered with a switch 32 for lowering to place the specific load on the club shaft 11, and then elevated with a switch 33 for elevation.

A deformation analysis of flat flexible gear and its equation of original curved surfaces

Abstract: The equation of the original curved surface of end harmonic gearing is determined by displacement analysis of flat flexible gear. The displacement analysis is also used to calculate the strength and rigidity of the gear. The latter is regarded as a circular plate with two concentrated loads, since its torsional rigidity is much larger than its bending rigidity. Small-deflection theory of thin plates is used to solve for the displacement of any point in the middle plane of the gear. New expressions are given for radial and tangential displacements of the middle plane under asymmetrical loading. A digital computer is used to obtain numerical values for the displacements.

In-plane and Out-of-plane Flexibility and Stress Intensification Factors of Smooth CSM Bends

Abstract: Twelve glass reinforced plastic pipe bends have been tested under the application of external loads. The bonds were made from Chopped Strand Mat (CSM) and unsaturated polyester resin. The test results in the form of flexibility and stress intensification factors were determined using the average thickness of the bend, and these are presented in comparison with BS 806 specifications. Reasonable correlation is found between experimental results and the prediction of isotropic smooth bend theory. Due to the composite nature of the bends, interlaminar shear stresses could be of importance. The presence of overlap joints is shown to increase the overall flexural rigidity of the pipe bends and straight pipes.

Press for extracting water from materials in tape form, especially for papermaking machines

Abstract: Press for extracting water from materials in the form of tapes or strips, in which one of the compression surfaces forming the constriction gap of the press consists of a flexible endless belt loaded by a supporting member, characterised in that the said endless belt 1,2 exerts its pressure on a part L of the tape 3 which is larger than the supported part 1 of the belt, by virtue of the flexural rigidity of the said belt. Application to papermaking machines.