Showing papers on "Flexural rigidity published in 1976"

Relation between Drape Coefficients and Mechanical Properties of Fabrics

Abstract: In this paper, drape coefficients and mechanical properties of 138 samples of woven fabrics are measured, and the relation between them is analyzed by means of residual-regression method. A linear equation by which the drape coefficient can be calculated from the mechanical properties is presented.As a result, it is shown that the value given by 3√ is most related with the drape coefficient, where B is bending rigidity (g•cm2/cm), W weight per unit area of fabric (mg/cm2).Next, the anisotropy in the bending property of fabric is examined, and we get an equation for the drape coefficient, by means of multiple regression method; Dn; =5.1+115.03√ +131.13√ +1.23√ where B90; is bending rigidity (g•cm2/cm) along warps, B0; along wefts, and B45; in bias directions.Finally, the stability of the drape shape is examined. It is found that as the hysteresis in fabric shearing and bending is large, the instability in the drape coefficient increases. From this fact, the experimental technique of drape testing is also discussed.

Inverse problem for a vibrating beam

Abstract: The problem of inferring the flexural rigidity and density of a beam from its eigenfrequencies is considered for the particular case in which one end is clamped. It is shown that three spectra associated with three sets of boundary conditions at the other end are required in order to insure a unique solution of the inverse problem. Furthermore, it is shown that this data set is equivalent to the information contained in the time history of the displacement and slope of the free end of the beam set in motion by a concentrated impulse.

Fluctuations and mechanical strength of α-helices of polyglycine and poly(L-alanine)

Abstract: By using the static correlations of fluctuations in the dihedral angles of the α-helices of polyglycine and poly(L-alanine) calculated previously, geometrical fluctuations of a section (consisting of up to 18 peptide units) of the α-helices of infinite length are calculated. These fluctuations are found to differ in some respects (e.g., the dependence of amplitudes on the length of section) from those of a circular rod made of homogeneous continuous material. However, the moduli of the mechanical strengths (tensile Young's modulus, bending Young's modulus, and the shear modulus) of a circular rod are calculated, whose geometrical fluctuations are approximately equal to the fluctuations of a section consisting of 18 peptide units. They are of the order of 1011 dyn/cm2. The tensile rigidity, flexural rigidity, and torsional rigidity are calculated to be 1.20 × 10−3 dyn, 2.46 × 10−19 dyn·cm2 and 1.79 × 10−19 dyn·cm2 for polyglycine, and 1.96 × 10−3 dyn, 4.05 × 10−19 dyn·cm2 and 3.28 × 10−19 dyn·cm2 for poly(L-alanine), respectively.

52—the bending and recovery properties of continuous-filament and staple-fibre yarns

Abstract: This paper presents an account of an experimental study of the pure-bending and recovery properties of both continuous-filament and spun yarns. The bending behaviour of yarns is approximately represented by a simple two-element rheological model of an elastic element and a single frictional element acting in parallel. The use of this model allows the bending deformation to be separated into an elastic and a frictional component, measured by the flexural rigidity and the frictional (or coercive) bending moment, respectively. An expression for the frictional couple in yarn-bending is derived from consideration of the lateral forces acting within the yarn and the degree of set of fibres in a twisted yarn. Bending experiments were made with nylon model plied yarns, conventional multifilament yarns, and staple-fibre yarns; it is shown that the level of residual fibre tension within both unset and set yarns can be estimated from the experimental values of the frictional bending moment by semi-empirical means. T...

Predicting the Flexural Rigidity of Thermoplastic Structural Foams

Abstract: the skin-core boundary is well-defined, structural foams may exhibit a continuous change in density throughout their cross sections. In addition the average void size and void size distribution may vary appreciably with distance from the skin. In spite of these considerations it has been common practice to approximate the load-deflection characteristics of structural foams in simple stress configurations such

A Model for Analytic Investigation of Three-Dimensional Head-Spine Dynamics

Abstract: : A three dimensional, discrete model of the human spine, torso and head was developed for the purpose of evaluating mechanical response in pilot ejection and it was developed in sufficient generality to be applicable to other body response problems, such as occupant response in aircraft crash and arbitrary loads on the head-spine system. There are no restrictions on the distribution or direction of applied loads, so a wide variety of situations can be treated. Results are presented for a variety of conditions, such as different rates on onset, ejection at angles, effects on lumbar curvature, and eccentric head loadings. It is shown that large initial curvatures and perfectly vertical acceleration loadings result in substantial flexural response of the spine, which cause large bending moments. It is further shown that the combination of the spines low flexural stiffness, initial curvature, and mass eccentricity are such that stability cannot be maintained in a 10 g ejection without restraints or spine-torso-musculature interaction.

Damper for sound conducted in solids

Abstract: A damper for sound conducted or propagating in solids is constructed to ecially damp oscillations or vibrations of the bending type particularly in plates, housings, girders, rails, rods, etc. The damper is connected to the structural member to be damped in such a manner that the damping force is taken up by the structure member itself. For this purpose a damping element having a high rigidity against bending is secured longitudinally to a structural member to be damped. The structural member and the element form the damping unit. Due to the high flexural rigidity, the damping element behaves like a solid platform or a fixed point, such that vibrations of the structural member cause a relative motion between the structural member and the damping element. This relative motion provides excellent damping characteristics which may even be improved by placing a viscous damping material between the structural member and the element.

Natural frequencies of orthotropic rectangular plates with varying thickness

Abstract: An approximate formula is derived for the estimation of the fundamental natural frequency of the simply supported orthotropic rectangular plate with thickness varying linearly in one direction. The accuracy of the formula and the influence of the flexural rigidity D*1 on the natural frequency are discussed.Subject Classification: [43]40.24.

Physical Interpretations of the Instabilities Encountered in the Deflection Equations of the Unconstrained Pipeline

Abstract: Phillips Petroleum Co. presents the results of a parametric study analyzing a pipeline displaced from the seafloor to some pipeline-construction configuration. For a pipeline modeled as having constant rigidity, horizontal tension, and submerged weight per unit length, there is a maximum value that the maximum sag-bend moment attains as the distance from the pin-supported end of the pipe to the seafloor increases. The pipeline is modeled as a continuous beam having a constant submerged weight per unit length and a constant horizontal tension or force with one end supported vertically by the seafloor. The governing differential equations are solved in terms of dimensionless combinations of the three characteristic variables--the submerged weight per unit length, the flexural rigidity, and the constant horizontal tension. This allows any possible pipeline configuration meeting the stated constraints to be analyzed and the maximum sag-bend moment to be specified. This maximum sag-bend moment is changed by varying the seafloor vertical force until a further change in seafloor reaction does not give a pipeline configuration. The maximum attainable maximum sag-bend moment may be then computed and graphed as a function of the three characteristic pipeline values named above.

[Mechanical studies on the dental bridges by the finite element method (2). --An idealized symmetrical bridge with a vertical load at the center of pontic-- (author's transl)].

Abstract: The biomechanical behavior of bridge support was studied by the finite element method. An idealized bridge model was constucted by using the previously reported tooth model as the two-sided abutment teeth. Under a vertical load at the center of pontic the stress distributions were shown in the constituent elements. Forces transmitted to the abutment teeth were calculated from these distributions. The results obtained were compared with theoretical models based on the beam theory in engineering. 1) For the finite element model, moment M and horizontal force H are given by (see article) wherein P is load, B is flexural rigidity of pontic, L is bridge span length, and KM and KH are spring constants of the supports with respect to moment and horizontal force, respectively. 2) If it is assumed that a dental bridge is a rigid body, the moment is underestimated and the horizontal force is neglected. 3) According to the fixed-ended-beam model which allows neither movement nor deformation of the supports, the moment is overestimated in many cases. 4) According to the general-beam model which allows the vertical movement and rotation of the supports, the moment is underestimated because of the assumption that no forces are acting in the longitudinal direction of beam.

Doubleecontact twooline meshing type wn gear

Abstract: PURPOSE:Provision of a WN gear featured in less fluctuation of flexural rigidity, prevention of impaired thread engagement due to manufacture/assembly erros or deflection under load, and reduced noise and vibration.

Hammerrshank of a piano action

Abstract: PURPOSE:To provide a hammer-shank of piano action which can be progressed of its flexural rigidity and be satisfied enough physically.

Determination of the elastic and damping properties of the human femur in bending

Abstract: The results of an experimental investigation of the deflection of the human femur subjected to a bending moment are presented. The existence of two principal bending planes is established. The equivalent flexural rigidity of the dry bone is calculated for both static and dynamic loading. It is found that the human femur has a nonlinear elastic characteristic. The stiffness and damping properties obtained in static and dynamic testing are compared.