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Showing papers on "Torsion (mechanics) published in 1970"


Journal ArticleDOI
O. L. Blakslee, D. G. Proctor, E. J. Seldin, G. B. Spence, T. Weng1 
TL;DR: The elastic constants of pyrolytic graphite which has been highly ordered by annealing under compressive stress have been determined by ultrasonic, sonic resonance, and static test methods.
Abstract: The elastic constants of pyrolytic graphite which has been highly ordered by annealing under compressive stress have been determined by ultrasonic, sonic resonance, and static test methods. Ultrasonic tests yielded the elastic constants c11, c12, c33, c44 = 1/s44, and the stress derivative of c33. The moduli 1/s11 and c44 were determined from the free flexural resonant vibrations of bars, and the shear modulus c44 also was determined from the fundamental torsional resonance of the bars and from the resonance of compound torsion oscillators composed of thin graphite disks with steel end pieces. Static tension, compression, and torsion tests on the pyrolytic graphite yielded a complete set of compliances (s11, s12, s13, s33, and s44). The following self‐consistent set of elastic constants (cij in units of 1011 dyn/cm2; sij in 10−11 cm2/dyn) has been deduced from the results: c11 = 106±2, c12 = 18±2, c33 = 3.65±0.10, c13 = 1.5±0.5, c44 = 0.018 to 0.035, 1/s11 = 102±3, 1/s33 = 3.65±0.10, s12 = −0.0016±0.0006,...

819 citations


Journal ArticleDOI
TL;DR: In this paper, an approximate theoretical treatment for small compressions of bonded rubber blocks is given, where the component of the compressive force arising from the bonded condition at the loaded surfaces is obtained from a pressure distribution within the block, given by the solution of the corresponding torsion problem.
Abstract: An approximate theoretical treatment is given for small compressions of bonded rubber blocks. The component of the compressive force arising from the bonded condition at the loaded surfaces is obtained from a pressure distribution within the block, given by the solution of the corresponding torsion problem. The bending of blocks is treated in a similar way, the pressure distribution in this case being derived from the corresponding bending stress function. The apparent shear of relatively thick blocks is then treated as a combination of shear and bending displacements. The location of an internal rupture and the deformation at which it occurs are also derived from a critical (negative) value of the pressure developed within the block, at which a small cavity increases indefinitely in size. The corresponding critical deformations are calculated for extension and bending displacements. The shear stresses developed at the bonded surfaces under extension, compression or bending displacements are also evaluated.

224 citations


Journal ArticleDOI
TL;DR: Superplastic behaviour in torsion was first reported by Saveur [2] and Pearson [3] as discussed by the authors, who first presented detailed observations of tensile superplasticity.
Abstract: Superplastic behaviour in torsion was first reported by Saveur [2] Pearson [3] first presented detailed observations of tensile superplasticity.

154 citations




Patent
Corker William R1
27 Nov 1970
TL;DR: In this paper, a high-frequency torsional oscillator for use in an optical scanner assembly, including a torsion rod whose ends are connected to a frame through a pair of flexural members, was presented.
Abstract: A high-frequency torsional oscillator for use in an optical scanner assembly, including a torsion rod whose ends are connected to a frame through a pair of flexural members which have lower torsional spring constants than the torsion rod. A mirror is attached to the torsion rod near its center, and a pair of rotors are attached to the torsion rod near its ends. Electromagnetic drivers are positioned near the rotors for imparting oscillatory motion thereto when the drivers are energized with a sinusoidally varying current. A phase-lock loop feedback system is used to drive the torsion rod assembly at a resonant frequency so that the mirror and the rotors oscillate with opposite phase, causing a pair of nodes to appear on the torsion rod between the mirror and the rotors.

64 citations


Journal ArticleDOI
R.R. Rizzo1, A.A. Vicario1
TL;DR: In this paper, a unique elasticity finite element program has been implemented which can deal with the general three-dimensional nature of axisym metric composite bodies, which is used to analytically predict the response of unidirectional composite tube specimens to uniaxial tension/compression.
Abstract: To gain needed insight into the effects of thickness to diameter ratio (t/Di), length to diameter ratio (l/Di ), and helical angle (α) on the response of laminated tubes in material characterization tests, a unique new elasticity finite element program has been implemented which can deal with the general three-dimensional nature of axisym metric composite bodies The program, which is utilized here to analytically predict the response of unidirectional composite tube specimens to uniaxial tension/compression, differs from the usual finite element formulations in that it accounts for general anisotropy In particular, it deals with all shear coupling terms and all six com ponents of stress The effects of different gripping methods are also considered Similar studies of torsion and internal pressurization tests will be reported in subsequent notesThis first phase of the study shows that while the response of axial and hoop wrapped tubes (α = 0°, 90°) is essentially indepen dent of length and thickness ra

60 citations


Journal ArticleDOI
TL;DR: In this article, Galerkin's procedure is applied to determine the natural frequencies of a straight cantilever blade with an asymmetric aerofoil cross-section executing coupled-bending torsion vibrations.

53 citations


Journal ArticleDOI
TL;DR: In this article, an approximate dynamical theory of torsion is developed which includes the effects of the warping and in-plane shearing deformations that, in general, accompany torsional deformation in cylindrical rods.

26 citations


Journal ArticleDOI
01 Jan 1970-Polymer
TL;DR: In this paper, an apparatus has been devised to measure the stress/temperature coefficients of elastomers in torsion, and the experiments carried out enable the temperature coefficient of the mean-square chain vector length r 0 2 to be derived.

26 citations


Journal ArticleDOI
A. D. Wilson1
TL;DR: Using holographic interferometry, the rotation of a rigid cylinder and the torsion of a flexible shaft (RTV silastic rubber) have been observed and the experimentally generated fringe patterns are compared with computed ones and good agreement is obtained.
Abstract: Using holographic interferometry, the rotation of a rigid cylinder and the torsion of a flexible shaft (RTV silastic rubber) have been observed. The experimentally generated fringe patterns are compared with computed ones and good agreement is obtained.

Journal ArticleDOI
01 Oct 1970

Journal ArticleDOI
TL;DR: In this article, the second-order torsion of an incompressible, isotropic, homogeneous, hyperelastic cylinder is reduced to a two-dimensional classical linear elasticity traction problem without body force.

Journal ArticleDOI
TL;DR: In this paper, the authors present an analysis of the behavior of the elastic buckler in the long-itudial and radial directions due to bending and non-uniform condition.
Abstract: AN ANALYTICAL STUDY OF THE ELASTIC BUCKLING BEHAVIOR OF THE FLANGES OF HORIZONTALLY CURVED I-SHAPED GIRDERS IS PRESENTED THE PREBUCKLING FLANGE STRESSES IN THE LONGITUDINAL AND RADIAL DIRECTIONS DUE TO BENDING AND NONUNIFORM TORSION ARE DETERMINED USING AN ELASTICITY APPROACH THE MAGNITUDES OF THESE STRESSES ARE COMPARED WITH THOSE RESULTING FROM A STRENGTH OF MATERIALS APPROACH USING THESE STRESSES AND THE FINITE DIFFERENCE METHOD, BUCKLING COEFFICIENTS, K, ARE OBTAINED BY TREATING THE FLANGES OF THE GIRDER AS ELASTICALLY RESTRAINED CURVED PLATES THE INFLUENCE OF CURVATURE AND THE RATIO OF BENDING STRESS TO WARPING NORMAL STRESS ON THESE BUCKLING COEFFICIENTS IS EVALUATED THE BUCKLING COEFFICIENTS ARE COMPARED WITH THOSE FOR RECTANGULAR PLATES WIDTH TO THICKNESS REQUIREMENTS BASED ON PREVENTING LOCAL BUCKLING IN THE ELASTIC RANGE ARE ALSO OBTAINED /ASCE/

Journal ArticleDOI
TL;DR: In this article, a general theory of torsion of tapered box girders of deformable cross section, its experimental substantiation, studies of the ultimate strength of box Girders, and the use of the theory derived for analysis of a really big bridge, are presented.
Abstract: A general theory of torsion of tapered box girders of deformable cross section, its experimental substantiation, studies of the ultimate strength of box girders, and the use of the theory derived for analysis of a really big bridge, are presented. Warping stresses and distortion stresses from transverse flexure are computed. A simple criterion is derived for load distribution on the bridge to ensure the greatest effects of bending and torsion. It is possible to use computers for practical computations; the presented solution is simplified and expressed in the form of formulas for less important cases. The analysis is applicable to straight tapered box girders of deformable cross section, and also for continuity over intermediate supports, and arbitrary end support conditions. It is also applicable to girders with rigid cross section.


Journal ArticleDOI
TL;DR: In this article, it was shown that a σ e curve can be obtained from torsion tests of a solid rod using an analysis similar to that used for obtaining secondary creep data from Torsion Tests.

Journal ArticleDOI
TL;DR: In this article, the resonance equations for the torsional vibrations of a symmetric, three-piece, cylindrical compound oscillator are derived for the determination of elastic constants of compression-annealed pyrolytic graphite, a highly anisotropic material.
Abstract: Methods of solution are given for the sonic resonances corresponding to the free flexural and torsional vibrations of an anisotropic bar of rectangular cross section The resonance equations for the torsional vibrations of a symmetric, three‐piece, cylindrical compound oscillator are derived The particular application of the methods and equations for the determination of some of the elastic constants of compression‐annealed pyrolytic graphite, a highly anisotropic material, is discussed

01 Jul 1970
TL;DR: In this paper, a simplified method for the Torsional analysis of SINGLE-SPAN or CONTINUOUS CURVED BOX Girders is presented.
Abstract: A SIMPLIFIED METHOD IS PRESENTED FOR THE TORSIONAL ANALYSIS OF SINGLE-SPAN OR CONTINUOUS CURVED BOX GIRDERS, WHICH, BY VIRTUE OF THEIR EXCELLENT STRENGTH IN RESISTING TORSION, ARE GENERALLY RECOGNIZED AS IDEAL SUPPORTING ELEMENTS FOR HORIZONTALLY CURVED STRUCTURES. UNDER MOST CONDITIONS ENCOUNTERED IN PRACTICE, THE BENDING AND TORSIONAL ANALYSIS OF CURVED BOX GIRDERS MAY BE UNCOUPLED AND INVESTIGATED INDEPENDENTLY. BY STRAIGHTENING THE CURVED GIRDER TO ITS FULL DEVELOPED LENGTH, THE BENDING MOMENTS AND VERTICAL SHEAR FORCES CAN BE READILY DETERMINED AS CUSTOMARILY DONE. THE PROPOSED METHOD SUGGESTS THAT THE TORSIONAL ANALYSIS CAN BE CARRIED OUT IN A SIMILAR MANNER, EXCEPT THAT (1) A STRAIGHT CONJUGATE BEAM SUBJECTED TO A DISTRIBUTED LOAD IN THE TORSIONAL MOMENT ANALYSIS, AND (2) A STRAIGHT CONJUGATE BEAM SUBJECTED TO A DISTRIBUTED LOAD FOR THE DETERMINATION OF THE ANGLES OF TWIST ARE TO BE CONSIDERED, WHERE M IS THE BENDING MOMENT OBTAINED IN THE APPROXIMATE FLEXURAL ANALYSIS, R IS THE RADIUS OF CURVATURE. THE APPLIED DISTRIBUTED TORQUE IN THE SPANWISE DIRECTION IS ALSO CONSIDERED. SINCE M/R IS A PARAMETER IN THE FORCING FUNCTION IN THE ANALYSIS, THE APPROXIMATE METHOD IS CALLED THE M/R-METHOD TO DIFFERENTIATE IT FROM THE CLASSICAL CONJUGATE BEAM METHOD FOR THE DETERMINATION OF BEAM DEFLECTIONS. THE ACCURACY AND LIMITATIONS OF THE APPROXIMATE METHOD ARE EXAMINED AS WELL AS SEVERAL OTHER ASPECTS RELATED TO THE PROBLEM IN GENERAL. IT IS FOUND THAT WITHIN THE LIMITS SPECIFIED, THE METHOD WILL GIVE RESULTS WITH SUFFICIENT ACCURACY FOR PRACTICAL PURPOSES.




Journal ArticleDOI
TL;DR: In this article, a specific design model standing in between a long prismatic shell and a classical beam is introduced to simplify the analysis, and flexibility, transformation, and equilibrium matrices are derived.
Abstract: The Bernoulli's hypothesis of plane cross sections remaining perpendicular to the deformed center line does not adequately approximate the deformation due to the torsion of a long prismatic shell (or thin-walled structure with open cross section). Due to the warping, the pure torsion gives rise to the occurrence of normal stresses in longitudinal direction. In order to simplify the analysis, a specific design model standing in between a long shell and a classical beam is introduced. The matrix force method proves to be a powerful tool for the analysis of such thin-walled members. The flexibility, transformation, and equilibrium matrices are derived. Two different techniques of matrix force method are presented in detail. Through a limiting process (when the torsional rigidity approaches zero) it is shown that the suggested procedure presents the generalization of the method used in the case of solid beam assemblages.

Journal ArticleDOI
TL;DR: In this article, the authors considered the problem of axisymmetric torsion by terminal loads of elastic shells of revolution, where shells are considered to be three-dimensional bodies occupying a region of space which includes all points whose distances from a given surface -the midsurface - do not exceed h/2, where h is the shell thickness.
Abstract: This paper is concerned with the problem of axisymmetric torsion by terminal loads of elastic shells of revolution. Such shells are considered here to be three-dimensional bodies occupying a region of space which includes all points whose distances from a given surface - the midsurface - do not exceed h/2, where h is the shell thickness. The analysis is based on the classical linear theory of elasticity for homogeneous, isotropic materials, and it may be regarded as an extension of the work described in [1] and [2]. The purpose of the present paper is to assess the quality of an approximate solution of the thin shell problem. The case of axisymmetric torsion of thin shells of revolution is perhaps tile simplest one for this purpose, since simple approximate solutions - constructed from two-dimensional shell theories or otherwise - are known [3]. Our results provide estimates, based on the three-dimensional theory of elasticity, for the error involved in a stress analysis in which the 'exact' solution is replaced by an approximate one.

Journal ArticleDOI
TL;DR: In this paper, the results of constant stress experiments, recovery, and multi-step creep tests in torsion in the nonlinear range were performed at different temperatures up to 160°F.
Abstract: Constant stress experiments, recovery, and multi‐step creep tests in torsion in the nonlinear range were performed at different temperatures up to 160 °F. It was found that the results could be described by a power function of time whose exponent was independent of stress and temperature. Most of the temperature effect and most of the nonlinearity were found in the coefficient of the time‐dependent term. The nonlinearity was described by the multiple integral representation, and the changes in stress were adequately predicted by the modified superposition method, except at the highest temperatures.


Journal ArticleDOI
TL;DR: In this article, the authors measured the torque as a function of the magnetic field required to maintain the plane of the sample at various fixed angles, ranging from 3° to 84° with respect to the magnetic fields, at sample temperatures of about 300°, 77°, and 4.2°K.
Abstract: Polycrystalline nickel films between 26 and 296 A in thickness were obtained by evaporation at normal incidence from tungsten filaments onto microscope‐slide glass substrates maintained at 75°C, at pressures between 6×10−10 and 12×10−10 Torr. In the same vacuum the substrates with their films were arranged to be parts of an automated torsion magnetometer in which the sample rotated about an axis in its own plane perpendicular to the magnetic field. Measurements were made of the torque as a function of the magnetic field required to maintain the plane of the sample at various fixed angles θ0 ranging from 3° to 84° with respect to the magnetic field, at sample temperatures of about 300°, 77°, and 4.2°K. The torque data were analyzed by a new method which permits detailed investigation of models for the magnetization. It is shown that for a single‐domain model with an out‐of‐plane uniaxial anisotropy, the saturation magnetization MS and the total anisotropy field S can be calculated from the magnitude and sl...

Journal ArticleDOI
TL;DR: Different versions of the skewed bending concept are compared and the effect of web reinforcement and prestress on the torsional strength are examined.
Abstract: Recent research on torsion in concrete members is reviewed and summarized. Different versions of the skewed bending concept are compared and the effect of web reinforcement and prestress on the torsional strength are examined. The validity and limitations of the different torsion-bending and torsion-shear interaction curves as well as several interaction surfaces are reviewed. Several essential areas for additional research on torsion and its inaction with shear and moment are delineated.

Book ChapterDOI
01 Jan 1970
TL;DR: In this article, the effects of concurrent temperature cycling through the phase transformation on the deformation characteristics of commercially pure titanium in tension and torsion and Ti-6Al-4V in tension have been studied.
Abstract: The effects of concurrent temperature cycling through the phase transformation on the deformation characteristics of commercially pure titanium in tension and torsion and Ti-6Al–4V in tension have been studied. A considerable increase in the creep rate is observed due to the phase transformation. For commercially pure titanium proportionality between transformation strain and applied stress is observed up to 500 psi in tension and torsion. It is further shown from the torsion data that the heating and cooling components of the transformation strain per cycle are equal. For Ti-6Al–4V the transformation strain and applied stress are proportional up to 400 psi in tension. The slope of the transformation strain vs. stress curve, δe/δσ, is in agreement with the theoretical predictions of Greenwood and Johnson. Static room temperature tension tests performed on Ti-6Al–4V after repeated temperature cycling through the phase transformation under stress, exhibited a decrease in Young's modulus, strength and ductility, while those of commercially pure Ti show a much smaller effect. A die-less wire drawing method utilizing transformation plasticity is described.

Patent
08 May 1970