Showing papers on "Flexural rigidity published in 1982"

Vibration Modes of Centrifugally Stiffened Beams

Abstract: The method of Frobenius is used to solve for the exact frequencies and mode shapes for rotating beams in which both the flexural rigidity and the mass distribution vary linearly. Results are tabulated for a variety of situations including uniform and tapered beams, with root offset and tip mass, and for both hinged root and fixed root boundary conditions. The results obtained for the case of the uniform cantilever beam are compared with other solutions, and the results of a conventional finite-element code.

A phalangeal fracture model—Quantitative analysis of rigidity and failure

Abstract: Nine types of internal fixation techniques were tested in 4-point bending using a pig metacarpal model for phalangeal fractures. Levels of bending rigidity and bending moments at failure were determined, and the modes of failure are described. Plate and screw fixation afforded the greatest rigidity, and epiphyseal fractures occurred, leaving intact the test section. Flexible wire loop fixation failed by wire cutting into bone when a square knot was used. Twisted wire unraveled when placed in tension. Depending on the fracture type and the wire placement, Kirschner wires failed either by slipping in the bone, twisting in the bone cortex, or bending at the bone cortex interface. Rigidity varied widely depending on the way in which the wires were employed.

Mechanical Properties of the Rice Panicle

Abstract: Curvature, bending moment, and second moment of stem cross-sectional area were evaluated from photographic data and used to compute flexural rigidity and Young9s modulus in the panicle rachis of rice, Oryza sativa L. `M-101.9 Flexural rigidity C , and its components E , Young9s modulus, and I , the moment of inertia of the area about the neutral axis, were evaluated 1.5 cm (tip), 9.5 cm (mid), and 16.5 cm (base) from the tip of the panicle rachis. In dynes per square centimeter, C increases from 1.1 × 10 3 near the tip to 1.09 × 10 4 in the middle to 5.35 × 10 4 in the basal region of the rachis. Of the components of C , the I changes have the larger effect, increasing from 2.12 × 10 −7 centimeters 4 near the tip to 8.21 × 10 −7 centimeters 4 in mid regions to 6.0 × 10 −6 centimeters 4 in the basal regions. Young9s modulus increases from 4.8 × 10 9 dynes per square centimeter near the tip to 1.4 × 10 10 dynes per square centimeter in mid regions then falls to 7.4 × 10 9 dynes per square centimeter near the base of the main stem. Values of Young9s modulus from Instron experiments were in satisfactory agreement with values calculated from the beam bending equation. Flexural rigidity in the curved region of the panicle proved independent of panicle load, indicating that the dissected panicle rachis behaves in some respects as a tapered loaded beam.

Dynamic Response of Plate on Elastic Half-Space

Abstract: Analytical results are presented for the dynamic response of a plate bearing on an elastic half-space and subjected to harmonic forces. The present work represents a departure from existing analyses in that herein both the flexibility and three-dimensionality of the plate are taken into account. Displacements and contact stresses are presented for square plates having a practical range of flexural stiffness. The harmonic analysis is conducted within the framework of a global stiffness solution, in which the plate and subgrade impedance matrices are formulated independently in accordance with a prescribed discretization pattern. Then compatibility of displacements and equilibrium of forces are enforced at the plate-subgrade interface. Solutions are presented for massless square plates subjected to harmonic point, uniform pressure, and moment loadings. The effect of the plate's mass on its response is studied by starting with a perfectly flexible massive plate and subsequently increasing the stiffness toward the limit of a completely rigid plate.

Spot-weldable lightweight composite material

Abstract: A lightweight composite material consisting of two metal sheets and an intermediate layer consisting of a mixture of resin and graphite and held between the metal sheets. The intermediate layer has a specifically limited thickness and a specifically limited graphite content, and the graphite has a specifically limited particle size distribution. The composite material is excellent in the spot weldability, bending rigidity, vibration-damping property and heat insulating property, and can be expected to be widely used as a material for automobile and further materials for industrial machine and architecture.

Circular Voided Concrete Slab Stiffnesses

Abstract: Finite element procedures for determining the plate bending stiffnesses of a circular voided slab are presented and the results are compared with those obtained from tests on model elastic voided plates. Preliminary investigations showed that a simplified plane-strain formulation, rather than a more complex general plane-strain formulation, could be used to determine the transverse flexural stiffness. Torsional stiffnesses were obtained from an analysis using the Prandtl stress-function formulation of the torsion problems. Tests were carried out on four epoxy-resin model plates having different void sizes. Good agreement was obtained between the finite element and experimental results. For design purposes, charts are presented which enable a designer of a concrete voided slab, having a Poisson's ratio of 0.2, to determine the values of the plate bending stiffnesses required for a thin plate analysis of such a slab. It is also shown that simple calculations based upon replacing a circular void with an equivalent square void are often adequate for design purposes.

Buckling of Stiffened Webs by Local Edge Loads

Abstract: A finite strip method is used for analysing the buckling of longitudinally stiffened web plates subjected to transverse local edge loading. The probLem is of particular importance for box girders, which have relatively weak flanges for resisting this type of buckling. Critical loads are obtained for square webs stiffened by single asymmetric longitudinal stiffeners positioned at one fifth of the depth from the loaded edge. A sufficient range of stiffener geometries is considered to enable the separate influences of the bending and torsional rigidities to be determined and two simple design rules are proposed. The first gives the lower limit on the bending rigidity for which the stiffener remains straight in the buckled configuration. The second gives the buckling strength of the web as a function of the torsional rigidty of the stiffener.

Plastic profile bar

Abstract: To increase the flexural stiffness of an extruded, board-shaped integral foam bar, reinforcing wires are incorporated into the non-porous integral foam skin during extrusion.

Bending Properties of Triaxially Woven Fabrics

Abstract: An earlier theqretical expression for the flexural rigidity oftriaxially woven fabrics is presented and is shown to predict isotropy in bending when the triaxial fabric is . constructed from identical yarns in each set. Experimental results at different angles of orientation with respect to the fabric machine direction confirm the theoretical findings and provide more data concerning this class of fabrics.

Determination of the flexural stiffness of thin plates from small deflection measurements using optical holography

Abstract: A technique is presented for accurate determination of the flexural stiffness of thin plates using optical holography. Measurements of the interference fringes on thin rhombic plates in anticlastic bending are used to calculate the components of curvature by a simple numerical method Control experiments on a metal plate give good agreement with the results of small deflection bending theory. The method appears ideally suited to the measurement of anisotropic flexural stiffness properties.

Flexural behaviour of concrete slabs reinforced with steel sheet

Abstract: This is a report on tests carried out on concrete slabs reinforced with bonded steel sheet, where flexural stiffness and ultimate capacity were improved versus conventional r. c. slabs. In the case of sheet metal, which has biaxial strength properties, the steel is far better utilized than in that of the uniaxial reinforcing bars, hence the slab structure is more economical. Fire- and corrosion protection is provided by a 10 mm coating of fire-shield plaster (or some other insulating agent).

Manufacture of high rigidity steel plate which is excellent in flexural rigidity

Abstract: PURPOSE:To elevate flexural rigidity of a steel plate without increasing wight of a steel material, by providing a deviation to plate thickness in the width direction of a steel plate, in the hot-rolling process of soft steel and high tension steel, and also finish-rolling it in a specific temperature area of >= Ar1 critical point. CONSTITUTION:In the hot-rolling process of soft steel and high tension steel which contains = 5% in an area of =Ar1 critical point, by which a hot-rolling steel plate which is excellent in fluxural rigidity in the rolling right angle direction, and when it is additionally cold-rolled, holding said thickness deviation, and recovery annealing is performed, its rigidity is further elevated.

Composite design method for masonry walls on steel beams

Abstract: The paper describes a design method for structures consisting of a heavily loaded masonry wall supported by a steel beam, taking account of the composite tied-arch behaviour of the wall and beam. The design approach is based on the assumption of triangular distributions of vertical stress at the wall–beam interface, the length of the distributions being a function of the beam-to-wall relative stiffness. In the design method the beam flexural stiffness is calculated to give an adequate distribution of the interface stress so that the maximum stress in the wall does not exceed allowable limits. The beam is also designed with flexural and shear strengths sufficient to resist the bending moment, tie force, and shear forees applied by the normal and shear interface loadings. Experimental evidence is cited to support the assumptions and the resulting design method.

Transverse Seismic Waves at Pipeline Junctions

Abstract: The effects of transverse seismic wave propagation at junctions in a buried pipeline network are studied. Relationships for the bending strain induced in the pipeline segments intersecting at a network junction are presented. It is shown that the bending strain is a function of the peak ground velocity, the propagation velocity of the transverse seismic waves with respect to the ground surface, the flexural rigidity of the pipeline segments, and the lateral stiffness of the soil surrounding the pipeline. An example problem is presented to illustrate the procedures for determining these bending strains.

Guide arm for high speed access

Abstract: PURPOSE:To improve an opened loop characteristic in a real operation area, by realizing a symmetrical structure and a symmetrical supporting mode having such light and rational dynamic rigidity as minimizes a moment of inertia in case of a seek operation. CONSTITUTION:An R/W guide arm 10 is formed so as to be almost symmetrical to an X axis, its tip part is made light by its truss structure, and also it is formed rationally against rigidity in the seek direction[direction (y)]. The surface of a carriage wall 2 and the edge part of the arm 10 are formed in one body with a guide pin 11, a rotation round the axis (y) is restricted by flexural rigidity of this guide pin 11, and the guide arm is made symmetrical. In this way, a bending mode in the Z direction is not present in a real operation area, and improvement of an opened loop characteristic is realized.

Cylinder block of engine

Abstract: PURPOSE:To reduce the resistance of the cylinder block of an engine wherein the flexural rigidity Kc of the crank shaft beared by a main shaft receiver is set at FL / 16(1.5-3.0X10 ), by setting the flexural rigidity Kb at (Kc/Kb)(4/L)>=10. CONSTITUTION:In the cylinder block wherein the flexural rigidity Kc of the crank shaft 5 beared by the main shaft receiver 6 formed in a partition wall 1 of a skirt 3 of the cylinder block is set at FL /16(1.5-3.0X10 ), the flexural rigidity Kb of the main shaft receiver is set at (Kc/Kb)(4/L)<=10. Thus, when an explosion load F is acted, the deviated position delta of the main shaft receiver 6 can be decreased, the resistance and weight can be reduced, the output performance and performance for fuel cost for the engine can be improved, and noises from the skirt outer wall can be suppressed.

Press-contacting device for x-ray photographic film

Abstract: PURPOSE:To obtain an X-ray photograph of superior image quality by giving prescribed bending rigidity to the front plate and back plate of a device which press-contacts a photographic film through pressing part of the back surface of the back plate. CONSTITUTION:In this press-contacting device, the contactness of such all layers as a front plate 1 and a cushion material 6 which cover an X-ray photographic film 3 by partially pressing the back surfaces of back plates 7 and 8 is improved. Then, EI(f)Xt>=8.0X10 kg.mm. and EI(b)Xt>=3.0X 10 kg.mm. , where EI(f) is the flexural rigidity of the front plate 1, EI(b) is the flexural rigidity of the back plates 7 and 8, and (t) is the thickness of the cushion material 6. Consequently, an X-ray photographic film 3 is pressed uniformly to improve its contactness over the entire surface, thus obtaining an X-ray image of superior quality.

Dynamic responses of graphite/epoxy laminated beam to impact of elastic spheres

Abstract: Wave propagation in 90/45/90/-45/902s and 0/45/0/-45/02s laminates of a graphite/epoxy composite due to impact of a steel ball was investigated experimentally and also by using a high order beam finite element. Dynamic strain responses at several locations were obtained using strain gages. The finite element program which incorporated statically determined contact laws was employed to calculate the contact force history as well as the target beam dynamic deformation. The comparison of the finite element solutions with the experimental data indicated that the static contact laws for loading and unloading (developed under this grant) are adequate for the dynamic impact analysis. It was found that for the 0/45/0/-45/02s laminate which has a much larger longitudinal bending rigidity, the use of beam finite elements is not suitable and plate finite element should be used instead.

Effect of Preferential Migration on the Flexural Rigidity of Jute Blended Yarns

Abstract: The properties of blended yarns, such as strength, flexural rigidity, and abrasion resistance are likely to depend not only on the ratio of the different fibers in the blend but also on the preferential disposition or preferential migration of constituent fibers in the yarn. Fabric properties like handle, drape, and strength may also be strongly influenced by the arrangement of fibers in the blended yarn cross section. Migration of fibers may thus be effectively used for producing desired change in yarn character. The nature of preferential migration in some jute blended yarns was reported earlier [6]. This communication reports the results of some studies on the possible effect of preferential migration on the flexural rigidity values of jute blended yarns. The processing methods of the jute blends, namely jute-mesta, jute-ramie, and jute-viscose of different blend ratios, as well as the method of determining the degree of preferential migration in these blends as characterized by the migration indices (core index and surface index), were described in detail earlier [6]. In addition, yarns containing a single component only were also spun following the same methods; these