72 results on '"Torsion -- Analysis"'
Search Results
2. Comb-actuated resonant torsional microscanner with mechanical amplification
- Author
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Arslan, A., Brown, D., Davis, W.O., Holmstrom, S., Gokce, S.K., and Urey, H.
- Subjects
Actuators -- Usage ,Microelectromechanical systems -- Design and construction ,Scanning devices -- Innovations ,Silicon-on-isolator -- Usage ,Torsion -- Analysis ,Engineering and manufacturing industries ,Science and technology - Published
- 2010
3. Design, fabrication, and characteristics of a MEMS micromirror with sidewall electrodes
- Author
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Yanhui Bai, Yeow, J.T.W., and Wilson, B.C.
- Subjects
Torsion -- Analysis ,Degrees of freedom (Mechanics) -- Evaluation ,Microelectromechanical systems -- Design and construction ,Silicon-on-isolator -- Mechanical properties ,Silicon-on-isolator -- Electric properties ,Engineering and manufacturing industries ,Science and technology - Published
- 2010
4. A lateral-axis microelectromechanical tuning-fork gyroscope with decoupled comb drive operating at atmospheric pressure
- Author
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Zhong Yang Guo, Long Tao Lin, Qian Cheng Zhao, Zhen Chuan Yang, Huikai Xie, and Gui Zhen Yan
- Subjects
Gyroscopes -- Design and construction ,Microelectromechanical systems -- Design and construction ,Torsion -- Analysis ,Tuning (Electronics) -- Analysis ,Engineering and manufacturing industries ,Science and technology - Published
- 2010
5. The effect of cross-sectional stem shape on the torsional stability of cemented implant components
- Author
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Kedgley, Angela E., Takaki, Sarah E., Lang, Pencilla, and Dunning, Cynthia E.
- Subjects
Implants, Artificial -- Design and construction ,Prosthesis -- Design and construction ,Torsion -- Analysis ,Arthroplasty -- Equipment and supplies ,Stability -- Analysis ,Engineering and manufacturing industries ,Science and technology - Abstract
Stability of a cemented implant, once the stem-cement interface has debonded, is reliant upon stem geometry and surface finish. There are relatively few studies addressing the effect of cross-sectional stem shape on cemented implant fixation. The purpose of this investigation was to compare the torsional stability of five different stem cross-sectional shapes--circular, oval, triangular, rectangular with rounded edges, and rectangular with sharp edges--under monotonically increasing and cyclic loading conditions. Seven samples of each stem geometry were tested. Stems were potted in bone cement and loaded to 5 deg of rotation. For monotonic loading, torque was applied at a constant rate of 2.5 deg/min. For cyclic loading, a sine wave torque pattern was applied, with a maximum magnitude that began at 4.5 Nm for 1500 cycles and then increased by 2.25 Nm every 1500 cycles until 5 deg of rotation. The rectangular stem with the sharp edges always provided the greatest resistance to torque, followed by the rectangular with rounded edges, triangular, oval, and circular. These results, including the effects of sharp corners, may differ for modes of loading other than torsion. These experimental results support the findings of earlier finite element models, indicating stem shape has a significant effect on resistance to torsional loading. [DOI: 10.1115/1.2720907] Keywords: implant fixation, implant design, cemented implant failure, torsional stability, arthroplasty
- Published
- 2007
6. Combined torsional-bending-axial dynamics of a twisted rotating cantilever Timoshenko beam with contact-impact loads at free end
- Author
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Sinha, Sunil K.
- Subjects
Torsion -- Analysis ,Science and technology - Abstract
In this paper, consideration is given to the dynamic response of a rotating cantilever twisted and inclined airfoil blade subjected to contact loads at the free end. Starting with the basic geometrical relations and energy formulation for a rotating Timoshenko beam constrained at the hub in a centrifugal force field, a system of coupled partial differential equations are derived for the combined axial, lateral and twisting motions which includes the transverse shear, rotary inertia, and Coriolis effects, as well. In the mathematical formulation, the torsion of the thin airfoil also considers a very general case of shear center not being coincident with the CG (center of gravity) of the cross section, which allows the equations to be used also for analyzing eccentric tip-rub loading of the blade. Equations are presented in terms of axial load along the longitudinal direction of the beam which enables us to solve the dynamic pulse buckling due to the tip being loaded in the longitudinal as well as transverse directions of the beam column. The Rayleigh-Ritz method is used to convert the set off our coupled-partial differential equations into equivalent classical mass, stiffness, damping, and gyroscopic matrices. Natural frequencies are computed for beams with varying 'slenderness ratio' and 'aspect ratio' as well as 'twist angles.' Dynamical equations account for the full coupling effect of the transverse flexural motion of the beam with the torsional and axial motions due to pretwist in the airfoil. Some transient dynamic responses of a rotating beam repeatedly rubbing against the outer casing is shown for a typical airfoil with and without a pretwist. [DOI: 10.1115/1.2423035]
- Published
- 2007
7. Buckling analysis of multiwalled carbon nanotubes under torsional load coupling with temperature change
- Author
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Xiaohu Yao and Qiang Han
- Subjects
Nanotubes -- Thermal properties ,Continuum mechanics -- Analysis ,Torsion -- Analysis ,Science and technology - Abstract
The torsional buckling analysis of multiwalled carbon nanotubes subjected to thermal load is studied and numerical results of the general case are presented for thermal effect. It is concluded that at room or lower temperature the critical torsional load of a multiwalled carbon nanotube increases as the value of temperature change increases, while at higher temperature than room temperature the critical torsional load decreases as the value of the temperature change increases.
- Published
- 2006
8. Effect of torsion on limiting temperature of steel structures in fire
- Author
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Wong, M.B.
- Subjects
Torsion -- Analysis ,Fire prevention -- Analysis ,Structural engineering -- Methods ,Engineering and manufacturing industries ,Science and technology - Abstract
In structural design of steel structures in fire, the failure criterion needs to be checked for all members under individual design actions or a combination of them. For space frames, combined design actions usually include forces due to bending, axial, shear, and torsion. An increase in temperature will result in changes to these forces as well as the diminution of the failure criterion due to reduced member capacities as a result of these combined design actions. This paper presents an elastic method for the prediction of limiting temperature of members in space steel frames. Since the critical temperature of the structure corresponds to the ultimate failure of the member with the lowest limiting temperature, this elastic method is equivalent to finding the location of the first plastic hinge in a general plastic analysis. By considering the degradation of the mechanical properties of steel in fire, a formulation based on the failure criterion of combined design actions including torsion is presented for limiting temperature calculation. The fundamentals of the solution strategy are also explained. CE Database subject headings: Torsion; Temperature; Steel structures; Fire hazards; Fire resistance.
- Published
- 2006
9. Static torsion capacity of a hybrid aluminum glass fiber composite hollow shaft
- Author
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Mutasher, S.A., Sahari, B.B., Hamouda, A.M.S., and Sapuan, S.M.
- Subjects
Aluminum compounds -- Research ,Aluminum compounds -- Structure ,Aluminum compounds -- Analysis ,Torsion -- Analysis ,Science and technology - Abstract
Abstract: Through out this paper an experimental study was carried out to study the static torsion capability of hybrid aluminum glass fiber composite shaft. A hybrid shaft was fabricated using [...]
- Published
- 2005
10. Bearing, shear, and torsion capacities of steel angel sections
- Author
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Trahair, N.S.
- Subjects
Structural engineering -- Research ,Steel, Structural -- Testing ,Shear (Mechanics) -- Analysis ,Torsion -- Analysis ,Engineering and manufacturing industries ,Science and technology - Abstract
Steel angle sections are commonly used as beams to support distributed loads which cause biaxial bending and torsion. However, many design codes do not have any design rules for torsion, while some recommendations are unnecessarily conservative, or are of limited application, or fail to consider some effects which are thought to be important. In this paper, proposals are developed for the section capacities of angle sections under bearing, shear, and uniform torsion. In a companion paper, consideration is given to the first-order elastic analysis of the biaxial bending of angle section beams, including the effects of restraints, and proposals are developed for the section moment capacities of angle sections under biaxial bending. The proposals in this and the companion paper can be used to design steel angle section beams which are laterally restrained so that lateral buckling and second-order effects are unimportant. DOI: 10.1061/(ASCE)0733-9445(2002)128:11(1394) CE Database keywords: Bearing capacity; Shear; Torsion; Angle section; Steel; Biaxial bending; Elastic analysis.
- Published
- 2002
11. Design of circular cross-section corner-filleted flexure hinges for three-dimensional compliant mechanisms
- Author
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Lobontiu, Nicolae and Paine, Jeffrey S.N.
- Subjects
Hinges -- Design and construction ,Torsion -- Analysis ,Stress analysis (Engineering) -- Research ,Engineering and manufacturing industries ,Science and technology - Abstract
The paper introduces the circular cross-section corner-filleted flexure hinges as connectors in three-dimensional compliant mechanism applications. Compliance factors are derived analytically for bending, axial loading and torsion. A circular cross-section corner-filleted flexure hinge belongs to a domain delimited by the cylinder (no fillet) and the right circular cross-section flexure hinge (maximum fillet radius). The analytical model predictions are confirmed by finite element simulation and experimental measurements. The circular cross-section corner-filleted flexure hinges are characterized in terms of their compliance, precision of rotation and stress levels. [DOI: 10.1115/1.1480022]
- Published
- 2002
12. Hover test of Mach-scale active twist rotor using piezo-bending-torsion actuators
- Author
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Bernhard, Andreas P.F. and Chopra, Inderjit
- Subjects
Vibration tests -- Analysis ,Vibration tests -- Methods ,Rotors -- Design and construction ,Rotors -- Testing ,Rotors -- Analysis ,Elasticity -- Analysis ,Torsion -- Analysis ,Mechanics -- Research ,Aerospace and defense industries ,Business ,Science and technology - Abstract
The active twist rotor investigated in this research is a derivative of the previously developed smart-active-blade-tip (SABT) rotor. On the SABT rotor, the blade tips are independently pitched, with respect to the main blade. A novel piezo-induced bending-torsion coupled actuator beam, located spanwise in the hollow midcell of the main rotor blade, is used to actuate the blade tip. When the blade tip is locked to the main blade, the actuator beam twists the entire blade. A Mach scale rotor with a 1.542 m diameter was hover tested, open loop, to evaluate the control authority for vibration reduction. A nonrotating tip-twist amplitude of 0.78 deg was achieved (below resonance, 150 V rms). Analysis indicates that no significant twist actuation degradation is expected at full rotor speed. In 2000-rpm hover (tip Mach 0.47), at 8-deg collective, and for a single blade actuation of 150 V rms at 1, 2, and 3 per revolution, respectively, the measured oscillatory thrust coefficients are 1.4 x [10.sup.-3], 0.55 x [10.sup.-3], and 0.7 x [10.sup.-3]. The corresponding finite element model estimated blade twist amplitudes are 0.8, 1,0, and 1.9 deg. Good correlation of the predicted and measured rotor thrust was achieved up to 3 per revolution. The hover test demonstrates the potential of the active twist rotor system using an internal actuation beam and warrants further research for a dedicated next-generation model-scale design and full-scale feasibility study.
- Published
- 2002
13. Coupled torsion-lateral stability of a shaft-disk system driven through a universal joint
- Author
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DeSmidt, H.A., Wang, K.W., and Smith, E.C.
- Subjects
Torsion -- Analysis ,Rotors -- Dynamics ,Load factor design -- Analysis ,Science and technology - Abstract
Understanding the instability phenomena of rotor-shaft and driveline systems incorporating universal joints is becoming increasingly important because of the trend towards light-weight, high-speed supercritical designs. In this paper, a nondimensional, periodic, linear time-varying model with torsional and lateral degrees-of-freedom is developed for a rotor shaft-disk assembly supported on a flexible bearing and driven through a U-joint. The stability of this system is investigated utilizing Floquet theory. It is shown that the interaction between torsional and lateral dynamics results in new regions of parametric instability that have not been addressed in previous investigations. The presence of load inertia and misalignment causes dynamic coupling of the torsion and lateral modes, which can result in torsion-lateral instability for shaft speeds near the sum-type combinations of the torsion and lateral natural frequencies. The effect of angular misalignment, static load-torque, load-inertia, lateral frequency split, and auxiliary damping on the stability of the system is studied over a range of shaft operating speeds. Other than avoiding the unstable operating frequencies, the effectiveness of using auxiliary lateral viscous damping as a means of stabilizing the system is investigated. Finally, a closed-form technique based on perturbation expansions is derived to determine the auxiliary damping necessary to stabilize the system for the least stable case (worst case). [DOI: 10.1115/1.1460907]
- Published
- 2002
14. Design considerations of rectangular electrostatic torsion actuators based on new analytical pull-in expressions
- Author
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Degani, Ofir and Nemirovsky, Yael
- Subjects
Actuators -- Design and construction ,Electrostatic apparatus and appliances -- Design and construction ,Torsion -- Analysis ,Engineering and manufacturing industries ,Science and technology - Abstract
An important design issue of electrostatic torsion actuator is the relative locations of the actuating electrodes, where the bias voltage is applied. These geometrical design parameters affect both the Pull-In angle as well as the Pull-In voltage. In this paper, a new approximated analytical solution for the Pull-In equation of an electrostatic torsion actuator with rectangular plates is derived. The analytical expression is shown to be within 0.1% of the one degree of freedom (1DOF) lumped-element model numerical simulations. Moreover, the analytical expressions are compared with the full coupled-domain finite-elements/boundary-elements (FEM/BEM) simulations provided by MEMCAD4.8 Co-solve tool, showing excellent agreement. The approach presented here provides better physical insight, more rapid simulations and an improved design optimization tool for the actuator. [661] Index Terms--Actuator, design, electrostatic, pull-in, torsion.
- Published
- 2002
15. Torsional surface waves in an initially stressed anisotropic porous medium
- Author
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Dey, S. and Sarkar, M.G.
- Subjects
Porous materials -- Thermal properties ,Torsion -- Analysis ,Wave propagation -- Analysis ,Science and technology - Abstract
It is well known that the homogeneous elastic half space does not allow the torsional surface wave to propagate. The present article attempts to study the possibility of propagation of such waves in a liquid-filled initially stressed poroelastic layer over nonhomogeneous half space. The study concludes that torsional surface waves may propagate in the poroelastic layer. The presence of fluid in pores and initial compressive stresses diminishes the velocity. The nonhomogeneity in rigidity and density of the half space also has a certain role to play in initiating, enhancing, or diminishing the velocity of torsional surface waves. DOI: 10.1061/(ASCE)0733-9399(2002)128:2(184) CE Database keywords: Porous media; Anisotropic materials; Surface waves; Velocity.
- Published
- 2002
16. Torsion of a circular compound bar with imperfect interface. (Brief Notes)
- Author
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Chen, T. and Weng, I.S.
- Subjects
Torsion -- Analysis ,Shear (Mechanics) -- Analysis ,Bars (Engineering) -- Research ,Science and technology - Abstract
The Saint-Venant torsion problem of a circular cylinder reinforced by a nonconcentric circular bar of a different material with an imperfect interface is studied. Conformal mapping together with a Laurent series expansion are employed to analyze the problem. The jump condition in either the warping function or the shear traction, characterizing the imperfect interface, is simulated in the transformed domain in an exact manner. Unlike the problem with perfectly bonded interface, the series solution has to be resolved by a truncation. Numerical illustrations are provided for the torsional rigidity of the cross section. In the case of perfect bonding case, our results agree with that reported in Muskhelishvili. [DOI: 10.1115/1.1406962]
- Published
- 2001
17. Theory of torsional chatter in twist drills: model, stability analysis and composition to test
- Author
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Bayly, Philip V., Metzler, Sandra A., Schaut, Adam J., and Young, Keith A.
- Subjects
Torsion -- Analysis ,Drilling and boring machinery -- Evaluation ,Stability -- Models ,Engineering and manufacturing industries ,Science and technology - Abstract
The mechanism of torsional chatter in drilling differs qualitatively and quantitatively from other types of chatter. In this paper we show that torsional chatter can be explained by the torsional-axial coupling inherent in a twisted beam; the beam 'untwists' and extends in response to an increase in cutting torque. Based on a model of this mechanism, predictions of stability boundaries and chatter frequencies are derived by frequency domain analysis, and confirmed by numerical simulation and experimental tests. The effect of the torsional-axial coupling is opposite that of traditional cutting in that an increase in cutting forces leads to axial extension and greater chip load. Because of this sign difference, the limiting depth of cut is governed by the positive real part of the frequency response function, which explains the unexpected fact that torsional chatter occurs below the natural frequency of the tool. [DOI: 10.1115/1.1381399]
- Published
- 2001
18. Thin-walled multicell beam analysis for coupled torsion, distortion, and warping deformations
- Author
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Kim, J.H. and Kim, Y.Y.
- Subjects
Mechanics -- Research ,Girders -- Analysis ,Torsion -- Analysis ,Surfaces, Deformation of -- Analysis ,Science and technology - Abstract
Due to the complicated deformations occurring in thin-walled multicell beams, no satisfactory one-dimensional beam theory useful for general quadrilateral multicells appears available. In this paper, we present a new systematic approach to analyze the coupled deformations of torsion, distortion, and the related warping. To develop a one-dimensional thin-walled multicell beam theory, the method to determine the section deformation functions associated with distortion and distortional warping is newly developed. In order to guarantee the singlevaluedness of the distortional warping function in multicells, distortional shear flows have been utilized. The superior result by the present one-dimensional theory is demonstrated with various examples.
- Published
- 2001
19. DISTORTION AND WARPING AT BEAM SUPPORTS
- Author
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Pi, Yong-Lin and Trahair, Nicholas S.
- Subjects
Structural analysis (Engineering) -- Research ,Girders -- Testing ,Torsion -- Analysis ,Weaving -- Analysis ,Engineering and manufacturing industries ,Science and technology - Abstract
When a doubly symmetric I-beam buckles elastically in a lateral-distortional mode, its web distorts, so that the two flanges have increased relative lateral displacements and may have different twist rotations. The centroid, shear center, and principal axes of the distorted cross section are all different from those of the undistorted cross section. The end connections to adjacent members may induce flange restraining moments that oppose warping deformations and modify the elastic buckling resistance. This paper investigates the effects on the lateral-distortional buckling of beams of web distortion and of the warping restraints induced by end-support conditions. It is found that a doubly symmetric I-section becomes unsymmetric during lateral-distortional buckling and that web distortion reduces the effective torsional and warping rigidities. The proposed approximations for the elastic lateral-distortional buckling resistances of beams without and with end warping restraints provide good predictions. Equations for the warping restraint stiffness induced by some commonly used end conditions are established. Comparisons with ABAQUS shell element results show that they provide good approximations.
- Published
- 2000
20. TORSIONAL SURFACE WAVES IN NONHOMOGENEOUS ANISOTROPIC MEDIUM UNDER INITIAL STRESS
- Author
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Dey, S., Gupta, A.K., Gupta, S., and Prasad, A.M.
- Subjects
Stress analysis (Engineering) -- Research ,Quantum theory -- Analysis ,Torsion -- Analysis ,Shear (Mechanics) -- Analysis ,Science and technology - Abstract
This paper studies the possibilities of propagation of torsional surface waves in nonhomogeneous anisotropic half-space under compressive initial stress. Two types of variations in nonhomogeneity, mainly hyperbolic and quadratic, have been discussed, and it is observed that in both cases the torsional surface wave will propagate in the media under consideration. The velocities of propagation have been computed and are presented in graphs. The study shows that for hyperbolic variation of nonhomogeneity, the increase of the anisotropic factor, increases the velocity of propagation, always keeping it more than that of shear wave in homogeneous medium. The presence of initial stress increases the velocity of propagation. In the case of quadratic variation it is found that the presence of initial stresses increases the velocity of propagation. The increase of anisotropy decreases the velocity, and the decrease in the nonhomogeneity factor increases the velocity, always keeping the velocity of torsional surface waves less than that of shear wave in the homogeneous medium.
- Published
- 2000
21. GENERAL CARRYOVER MATRIX OF PLANE ROD LOADED PERPENDICULAR TO ITS PLANE
- Author
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Artan, R.
- Subjects
Matrix mechanics -- Analysis ,Bars (Engineering) -- Evaluation ,Load factor design -- Analysis ,Torsion -- Analysis ,Science and technology - Abstract
The main purpose of the present article is to exhibit the power and potential of the initial values method by means of the solution of a crucial problem. First, the initial values method is presented and a general carryover matrix is obtained for plane rods loaded perpendicular to their plane. Then an example is solved and. the advantages of the method are depicted.
- Published
- 2000
22. 3D WIND-EXCITED RESPONSE OF SLENDER STRUCTURES: CLOSED-FORM SOLUTION
- Author
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Piccardo, G. and Solari, G.
- Subjects
Vibration research -- Analysis ,Storm surges -- Environmental aspects ,Torsion -- Analysis ,Structural analysis (Engineering) -- Research ,Load factor design -- Analysis ,Engineering and manufacturing industries ,Science and technology - Abstract
Along-wind, crosswind, and torsional vibrations of structures are different aspects of the same physical phenomenon. Despite this fact, each aspect has been the object of numerous studies involving lines of research that have frequently been independent of each other. These independent lines of research have often been characterized by notable inconsistencies and clashes. This paper proposes a single coherent formulation that provides compact expressions for estimating the along-wind, crosswind, and torsional response based on a generalized gust factor approach. It presents the wind-loading model and uses a generalized equivalent spectrum technique to derive closed-form solutions of the 3D wind-excited response of slender structures and structural elements. This extends a solution previously obtained for along-wind vibrations to the crosswind and torsional response. Numerical examples are provided that illustrate the simplicity and precision of this method. Because of this simplicity and precision, the method is suitable for use in design offices as a means of providing rapid estimates of the dynamic response of slender structures to gust buffeting actions. In particular, the estimates of the crosswind and torsional response will allow the designers to make more informed decisions on when to conduct physical model studies in boundary-layer wind tunnels.
- Published
- 2000
23. Recent approaches to shear design of structural concrete
- Author
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Darwish, M. Nasser, Gesund, Hans, and Lee, Douglas D.
- Subjects
Concrete construction -- Research ,Shear (Mechanics) -- Analysis ,Structural engineering -- Research ,Struts (Engineering) -- Research ,Torsion -- Analysis ,Engineering and manufacturing industries ,Science and technology - Published
- 2000
24. EXPERIMENTAL VALIDATION OF SMEARED ANALYSIS FOR PLAIN CONCRETE IN TORSION
- Author
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Karayannis, Chris G. and Chalioris, Constantin E.
- Subjects
Concrete -- Cracking ,Torsion -- Analysis ,Shear (Mechanics) -- Models ,Girders -- Design and construction ,Engineering and manufacturing industries ,Science and technology - Abstract
This is the second of two papers concerned with the development and the application of a smeared crack model for the description of the behavior of concrete elements in torsion. The first paper presented the development of an efficient model for the torsional analysis of concrete that utilizes a special numerical technique, which is properly adapted to include the smeared crack approach. This paper presents the validation of the analytical model by providing comparisons between analytically predicted behavior curves and experimentally obtained ones. The experimental data used in this paper comprise a series of tests in pure torsion conducted for this purpose and a database of experimental information compiled from works around the word, in an attempt to establish the validity of the proposed approach based on a broad range of parametric studies. From the comparisons between the predicted and the measured data, it is concluded that the proposed approach describes very well the behavior of concrete elements in pure torsion and yields satisfactory results for the case of nonrectangular elements subjected to combined torsion with flexure, shear, and axial force.
- Published
- 2000
25. SMEARED CRACK ANALYSIS FOR PLAIN CONCRETE IN TORSION
- Author
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Karayannis, Chris G.
- Subjects
Concrete -- Cracking ,Torsion -- Analysis ,Structural engineering -- Models ,Stress analysis (Engineering) -- Analysis ,Engineering and manufacturing industries ,Science and technology - Abstract
This is the first of two papers addressing the efficient approach of the torsional behavior of concrete elements through smeared crack analysis. This paper presents the development of an analytical model for the behavior of concrete elements in increasing torsion. The model is based on a special numerical technique that employs constitutive relations expressed in terms of normal stress and crack width, for the behavior of the crack process zones. The width of a crack process zone is considered as a material property and is estimated through comparisons between analytical and experimental data. The method is not restricted by the cross section shape because the analysis includes numerical mapping. Examination of the objectivity of the proposed analysis in relation to the used mesh density is included in the study. The proposed approach is also applicable to concrete elements subjected to torsion combined with flexure, shear, and axial force. Validation of the analytical model derived in this paper is demonstrated in a companion paper using extensive comparisons between predicted and experimentally obtained behavior curves and ultimate torque values.
- Published
- 2000
26. Torsion of a viscoelastic cylinder
- Author
-
Batra, R.C. and Yu, J.H.
- Subjects
Torsion -- Analysis ,Viscoelasticity -- Analysis ,Cylinder (Mathematics) -- Models ,Oscillation -- Analysis ,Science and technology - Abstract
The article discusses the finite torsional deformations of a homogeneous and isotropic viscoelastic circular cylinder. Transitional oscillations of the cylinder appear to be in agreement with the constitutive relation influenced by deviatoric Cauchy stress tensor the left Cauchy-Green tensor, and the Green-St. Venant strain tensor.
- Published
- 2000
27. Explicit modal analysis of an axially loaded Timoshenko beam with bending-torsion coupling
- Author
-
Banerjee, J.R.
- Subjects
Finite element method -- Analysis ,Modality (Logic) -- Usage ,Torsion -- Analysis ,Girders -- Usage ,Science and technology - Abstract
Research describes derivation of an analytical procedure for analyzing axially loaded bending-torsion coupled Timoshenko beam by incorporating exact frequency equation and mode shape expressions. Data show that the new theory can be used to validate finite element and other methods.
- Published
- 2000
28. LARGE DEFORMATION OF INELASTIC LARGE SPACE FRAME. I: ANALYSIS
- Author
-
Hori, Akio and Sasagawa, Akira
- Subjects
Deformations (Mechanics) -- Models ,Structural frames -- Design and construction ,Stress-strain curves -- Models ,Torsion -- Analysis ,Engineering and manufacturing industries ,Science and technology - Abstract
A member model divided into subelements along the member axis with end fibers is developed for material and geometrical nonlinear analysis of a space frame structure. The fiber stress-strain relationship is an extended Ramberg-Osgood model. To assume appropriate stiffness on the alternative of fiber loading or unloading, a trial stiffness selection procedure is presented. Analytical increments for an overall frame are set relatively large for application to a frame with many members. Analytical results for a simple truss agreed well with experimental results and simulated the complicated behavior of a web member, which first buckled slightly, then was unloaded, and finally rebuckled in another mode under a monotonous loading.
- Published
- 2000
29. The influence of intrinsic strain softening on strain localization in polycarbonate: modeling and experimental validation
- Author
-
Govaert, L.E., Timmermans, P.H.M., and Brekelmans, W.A.M.
- Subjects
Deformations (Mechanics) -- Analysis ,Polycarbonates -- Analysis ,Stress-strain curves -- Evaluation ,Torsion -- Analysis ,Science and technology - Abstract
The post-yield behavior of glassy polymers comprised of intrinsic strain softening and strain hardening can be validated using compressible Leonov model extended to such analyses. Results point out that the intrinsic strain softening effect is the primary cause for localization phenomenon in polycarbonate.
- Published
- 2000
30. Models for cyclic ratchetting plasticity-integration and calibration
- Author
-
Ekh, Magnus, Johansson, Anders, Thorberntsson, Hans, and Josefson, Lennart B.
- Subjects
Plasticity -- Models ,Metals -- Hardenability ,Torsion -- Analysis ,Science and technology - Abstract
This article discusses three different ratchetting models for metals to predict rachetting behavior of tension-torsion specimen using FE code ABAQUS.
- Published
- 2000
31. Anisotropic nonlinear kinematic hardening rule parameters from reversed proportional axial-torsional cycling
- Author
-
Moosbrugger, J.C.
- Subjects
Anisotropy -- Models ,Torsion -- Analysis ,Machinery, Kinematics of -- Research ,Plasticity -- Analysis ,Science and technology - Abstract
This article presents a methodology to determine Armstrong-Frederick type kinematic hardening rule parameters for analysis of cyclic plasticity and viscoplasticity of metals. Data show that axial-torsional cycling responses of type 304 tubular stainless steel specimens improved using this rule.
- Published
- 2000
32. Investigation of Torsion Springs by Considering the Friction and the End Effect
- Author
-
M.H. Wu and W. Hsu
- Subjects
Mechanical engineering -- Research ,Computer simulation -- Analysis ,Nonlinear theories -- Analysis ,Springs -- Research ,Torsion -- Analysis ,Deformations (Mechanics) -- Analysis ,Engineering and manufacturing industries ,Science and technology - Abstract
In this study, the nonlinearity in moment and angular displacement of torsion springs is studied analytically and experimentally. It is shown that the inclined angles at both ends have direct effects on the nonlinearity of a constant-pitch torsion spring. Also, an algorithm for determining the friction between the spring coils in close-wound torsion springs is proposed. From the comparison to experimental data, it is found that the spring rates are different at forward and backward strokes. The dynamic equations for the close-wound torsion spring is also derived by considering the friction between the spring coils, and two different natural frequencies are found in simulation.
- Published
- 1999
33. Torsion of polygonal bar with core of different material
- Author
-
Wang, C.Y.
- Subjects
Bars (Engineering) -- Analysis ,Structural design -- Research ,Torque -- Research ,Torsion -- Analysis ,Science and technology - Abstract
The torsion of a compound bar is studied by eigenfunction expansion and collocation. The bar has a regular polygonal cross section bonded with a circular core of different material. It is found that the torque is insensitive to the core size when the latter is less than 0.2 of the maximum dimension. Otherwise, the torque is highly dependent on the core size ratio and the shear moduli ratio of the two materials. The results obtained should be useful in the design of torsion members.
- Published
- 1999
34. Bending-torsion response of rib-reinforced cantilever plates
- Author
-
Kawiecki, Grzegorz
- Subjects
Deformations (Mechanics) -- Analysis ,Plates (Engineering) -- Analysis ,Torsion -- Analysis ,Science and technology - Abstract
The objective of this paper is to present the feasibility of applying Vlasov's theory of thin walled bars to model the behavior of rib-reinforced cantilevered plates. A simple analytical model based on Vlasov's theory is presented and validated against experimental results. It is shown that the presented theoretical method is simple and sufficiently accurate to be used as a design tool. The presented approach is also valid for plates fabricated from composite materials.
- Published
- 1999
35. Elasticity solution for torsional rigidity of pretwisted composite strips
- Author
-
Makeev, Andrew and Armanios, Erian A.
- Subjects
Composite materials -- Analysis ,Laminated materials -- Analysis ,Torsion -- Analysis ,Science and technology - Abstract
The tension-torsion problem for pretwisted antisymmetric laminated composite strips is formulated without ad hoc shell-type assumptions. No restrictions regarding the thickness-to-width aspect ratio are made. The elasticity equations are derived first and solved exactly for the torsional rigidity of orthotropic strips. An approximate solution is derived for angle-ply laminates. The torsional rigidity predictions are compared with a shell-type closed-form solution and finite-element simulations. An iterative method, which allows for the development of closed-form one-term approximations in a number of boundary-value problems, is presented. The accuracy of the method is illustrated by comparison with exact solutions for two benchmark problems.
- Published
- 1999
36. Torsional Wave Propagation in a Circular Cylinder with a Periodically Corrugated Outer Surface
- Author
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J.O. Kim
- Subjects
Mechanical engineering -- Research ,Torsion -- Analysis ,Elastic waves -- Analysis ,Perturbation (Mathematics) -- Analysis ,Science and technology - Abstract
The paper describes a theoretical study on the speed of torsional elastic waves propagating in a circular cylinder whose outer radius varies periodically as a harmonic function of the axial coordinate. An approximate solution for the phase speed was obtained by using the perturbation technique for sinusoidal modulation of a small amplitude. This shows that the wave speed in the cylinder with a corrugated outer surface is less than that in a smooth cylinder by the square of the amplitude of the surface perturbation. This theoretical prediction reasonably agrees with an experimental observation reported earlier. It is also shown that the wave speed reduction due to the surface corrugation becomes larger for a thinner cylinder and for a bigger density of corrugation.
- Published
- 1999
37. Plastic torsion analysis of monosymmetric and point-symmetric beams
- Author
-
Trahair, N.S.
- Subjects
Steel I-beams -- Analysis ,Torsion -- Analysis ,Structural design -- Research ,Steel, Structural -- Research ,Engineering and manufacturing industries ,Science and technology - Abstract
This paper extends a simple method of analyzing the plastic torsion collapse of compact equal flange I-section beams to monosymmetric and point-symmetric beams. The method can be used manually, is much easier than elastic analysis, and is no more difficult than the plastic collapse analysis of beams in bending. The use of plastic torsion analysis avoids the conservatism of first yield analysis and design because it accounts for the spread of plasticity through the cross section and the redistribution of torque that occurs in redundant members after the first hinge forms. Designs based on plastic analyses of torsion will lead to significant economies over the first yield designs based on elastic analysis. Equations are developed in this paper for the uniform torsion plastic torques and for the plastic bimoments of monosymmetric I-sections, lipped and unlipped channels, and equal flange lipped angles, and of point-symmetric lipped and unlipped Z-sections. A worked example of the plastic torsion collapse and design of a lipped channel is present.
- Published
- 1999
38. Dynamic torsional response of a laminated circular disc
- Author
-
Zhang, Xiangzhou and Hasebe, Norio
- Subjects
Torsion -- Analysis ,Laminated materials -- Research ,Science and technology - Abstract
Harmonic and transient torsional responses of a laminated circular disc (or a laminated circular cylinder), caused by torques applied on both ends of the disc, is investigated with use of a continuous analysis. By the analysis, the difficulty brought about by multitudinous reflections and transmissions, taking place at the interfaces of the laminated medium, can be bypassed. The continuous analysis is based on the recognition that stresses at periodic locations in a periodic structure must vary smoothly; therefore these discrete values as a whole approximately form a continuous function, which can be treated analytically. Via the analysis, it is concluded that the real, heterogeneous laminated disc can be modelled into a homogeneous, effective one. The corresponding effective solution provides accurate or exact values of displacements and stresses at the periodic locations of the laminated disc. The density of the effective disc is not a geometric-material constant; it depends on, among others, the frequency and other vibration parameters in the problem. Numerical results are given to validate the analysis.
- Published
- 1999
39. Dynamics of multicell, thin-walled beams with regular cutouts
- Author
-
Capuani, D., Laudiero, F., and Savoia, M.
- Subjects
Shear (Mechanics) -- Analysis ,Girders -- Models ,Torsion -- Analysis ,Science and technology - Abstract
In a previous paper, the writers presented a one-dimensional analytical model for the static analysis of multicell, thin-walled beams with nonhomogeneous cross sections. The proposed model accounts for shear deformations due to nonuniform bending and torsion supplementing the primary effects considered by the classical models. Here, the constitutive relations for the beam model are given and the dynamic analysis of the shear core is considered by a proper generalization of the continuous formulation. An algebraic procedure is given to evaluate the equivalent mechanical properties of the cross section. Moreover, a one-dimensional hierarchical finite element formulation is proposed for displacements and rotations. The proposed model is shown to cover the analysis of multicell, thin-walled beams, having regular cutouts, as is typical of shear cores of tall buildings. The applications include solutions to both the continuous and the discrete models.
- Published
- 1998
40. Generalized warping torsion formulation
- Author
-
Schulz, Mauro and Filippou, Filip C.
- Subjects
Torsion -- Analysis ,Deformations (Mechanics) -- Analysis ,Bars (Engineering) -- Analysis ,Science and technology - Abstract
A general formulation for torsional-flexural analysis of beams with arbitrary cross section is presented in a general coordinate system. The theory maintains Vlasov's approach in terms of generalized strains and stresses and yields the same system of differential equations. The common hypothesis of transversely rigid cross section, which overestimates the effective flexural and torsional section stiffness, is replaced by the assumption that stresses in the plane of the cross section are small. The resulting theory reduces to the exact solution of Timoshenko when warping effects are neglected. Shear stresses due to shear forces, warping torsion, and Saint-Venant torsion are determined as the gradient components of a unique potential function. These equations are solved with the finite element method, which also provides the flexural and torsional section stiffness and the shear center. Numerical examples are presented and results are compared with full three-dimensional finite element analyses. The formulation is simple and, in spite of the limitations of the simplifying hypotheses, sufficiently accurate for many engineering applications, bypassing costly three-dimensional finite element analyses.
- Published
- 1998
41. System identification and adaptive control of the multi-axis bending and twisting process
- Author
-
Sun, Wei-Ching and Stelson, Kim A.
- Subjects
Adaptive control -- Methods ,Bending -- Analysis ,Torsion -- Analysis ,Engineering and manufacturing industries ,Science and technology - Abstract
An adaptive control scheme for the multi-axis bending and twisting process based on system identification of process models is presented. Three system identification methods, the frequency-response, the least-squares, and the singular value decomposition methods, have successfully identified the process models. Control based on these identified process models performed better than control based on the theoretical process models proposed by Luo et al. (1996). The shape errors between the intrinsic geometric quantities of the actual and desired parts are applied to the inverse identified process models to calculate incremental changes in axis commands for subsequent iterations. Comparison with experimental results demonstrates that adaptive control based on the identified process models achieves more rapid convergence of the iterations than the previous approach.
- Published
- 1997
42. Torsional vibration control of a shaft through active constrained layer damping treatments
- Author
-
Shen, I.Y., Guo, Weili, and Pao, Y.C.
- Subjects
Vibration -- Control ,Torsion -- Analysis ,Damping (Mechanics) -- Design and construction ,Science and technology - Abstract
This paper proposes a hybrid damping design to control torsional vibration of a shaft with a circular cross section through use of actively constrained layer (ACL) damping treatments proposed by Baz (1993) and Shen (1993, 1994a). The ACL damping treatment consists of a piezoelectric constraining layer and a viscoelastic shear layer wrapping around the shaft in the form of a helix. In addition, the angular displacement of the shaft is fed back to regulate the helical motion of the piezoelectric constraining layer. The equation of motion of this design is derived, and its stability and controllability are discussed. Finally, numerical examples show that this ACL design can reduce torsional vibration of a shaft. A sensitivity analysis shows that ACL is most effective in suppressing those modes with significant torsional vibration response. Stability, in general, is not a critical factor in designing ACL systems, because the piezoelectric strain of the constraining layer at the threshold of instability is too large to occur.
- Published
- 1997
43. 'Snapping' torsional response of an anisotropic radially loaded rotor
- Author
-
Bently, D.E., Goldman, P., and Muszynska, A.
- Subjects
Rotors -- Vibration ,Torsion -- Analysis ,Fracture mechanics -- Analysis ,Engineering and manufacturing industries ,Science and technology - Abstract
A rotor system with two orthogonal lateral and two angular (torsional) degrees of freedom is considered. The rotor has asymmetry of the lateral stiffness and is laterally loaded with a constant radial force and a rotating unbalance. Constant driving and load torques are applied to the rotor. The important part of the research includes an analysis of 'snapping' action, when, during rotation, the rotor experiences a peak of torsional acceleration. This occurs when the 'strong stiffness' axis of the anisotropic rotor passes under the axis of the sideload. The numerical simulation of the analytical model exhibits a snapping (accelerated) torsional response of the rotor at twice synchronous frequency (2x), and it is especially pronounced at 1x and 2x torsional resonances. The snapping response can initiate a rotor crack in the area of stress concentration, can stimulate existing crack propagation, and can be a cause of the coupling failure. The analytical results are obtained by the Averaging Method application. They confirm the numerical results and show the possibility of combination resonance occurrences. The synchronous dynamic stiffness for the frequency range around 1x lateral resonance is analytically obtained. The specific shape of the quadrature dynamic stiffness component can serve as a shaft crack indicator and can be used for early detection of a lateral crack on the rotor.
- Published
- 1997
44. Buckling analysis of elastic space rods under torsional moment
- Author
-
Goto, Yoshiaki, Li, Xiao-Song, and Kasugai, Toshihiro
- Subjects
Bars (Engineering) -- Analysis ,Strength of materials -- Analysis ,Deformations (Mechanics) -- Analysis ,Torsion -- Analysis ,Science and technology - Abstract
The buckling behavior of elastic space rods under torsional moment is studied theoretically. A consistent method is developed to identify the buckling torsional moment as well as to trace the postbuckling path. Since this buckling phenomenon accompanies a nonlinear interaction between flexural deformation and torsional deformation, a special consideration has to be made in the treatment of finite rotations in three-dimensional space. First, a buckling analysis based on a rigorous nonlinear beam theory is developed to identify the bifurcation moment. This analysis precisely takes into account the prebuckling torsional deformations as well as the effect of axial compressive force. Next, the postbuckling behavior is analyzed by the transfer matrix technique, which was previously presented by the writers. With this method, the buckling and postbuckling behavior of space rods under torsional moment are examined with an emphasis on the effect of cross-sectional shapes as well as axial compressive force.
- Published
- 1996
45. Torsion in symmetric structures due to ground-motion spatial variation
- Author
-
Heredia-Zavoni, Ernesto and Barranco, Federico
- Subjects
Torsion -- Analysis ,Earthquake engineering -- Analysis ,Science and technology - Abstract
A random-vibration analysis is performed for the torsional response of symmetric structural systems subjected to spatially varying earthquake ground motion. Torsional effects are assessed by means of an equivalent eccentricity that can be expressed in terms of the system lateral displacement and rotation variances. Two case studies of systems consisting of a rigid slab supported by columns and walls are presented. A parametric analysis is conducted to evaluate the influence of local soil conditions and incoherence effects on the torsional responses of these systems. The results show that depending on the aspect ratio of the system, the soil conditions, and the times for seismic waves to travel across the base of the system, torsional effects can be significant especially for structural systems with fundamental periods close to the predominant period of the ground.
- Published
- 1996
46. Torsional instabilities in a system incorporating a Hooke's joint
- Author
-
Asokanthan, S.F. and Hwang, Ming-Chang
- Subjects
Kinematics -- Research ,Structural dynamics -- Models ,Torsion -- Analysis ,Science and technology - Abstract
Dynamic stability analysis of a driveline which incorporates a Hooke's joint is presented in this paper. In particular, torsional instabilities due to fluctuating angular velocity ratio across the joint are examined. The method of averaging is used to establish the critical speed ranges by considering the linearized equations which govern the torsional motion of the system. Within these ranges, parametric instability characterized by exponential build up of response amplitudes of the torsional modes occur. Closed form conditions for onset of sub-harmonic as well as sum-type combination resonance have been established. The significance of the sum-type combination resonance in a typical diesel hydraulic locomotive driveline has been demonstrated. Difference-type combination resonance has been shown to be absent. The instability conditions indicate the range of driveshaft speeds to be avoided during the design of a driveline which employs a Hooke's joint.
- Published
- 1996
47. Dynamic response of box tubes to combined shear and torsion
- Author
-
Mo, Y.L. and Yang, R.Y.
- Subjects
Reinforced concrete construction -- Research ,Trusses -- Models ,Shear (Mechanics) -- Analysis ,Torsion -- Analysis ,Structural dynamics -- Models ,Engineering and manufacturing industries ,Science and technology - Abstract
Based on equilibrium and compatibility conditions, as well as a stress-strain relationship for softened concrete, a truss model theory for reinforced-concrete structural walls subjected to static shear was applied to determine the shear-force-displacement relationship as the primary curve for dynamic analysis. Similarly, the torque-twist relationship of reinforced-concrete box tubes subjected to static torsion was able to be determined using the truss model theory. In this paper, the inelastic dynamic response of reinforced-concrete box tubes to combined shear and torsion is predicted using the primary curve obtained by the interaction relationship between shear and torsion, the hysteretic model proposed for reinforced-concrete structures under shear or torsion, and the linear acceleration step-by-step method. Further, parametric studies are performed using the proposed algorithms.
- Published
- 1996
48. Inelastic torsion for preliminary seismic design
- Author
-
Bertero, Raul D.
- Subjects
Torsion -- Analysis ,Structural stability -- Analysis ,Structural analysis (Engineering) -- Methods ,Buildings -- Earthquake effects ,Engineering and manufacturing industries ,Science and technology - Abstract
Because of torsion, the demanded strength and interstory drift at certain parts of the structure increase above those required by just translational deformation. These effects differ for elastic and inelastic behavior, tending to be larger when inelastic behavior involves a torsional mechanism of the structure. A clear contradiction exists in the present consideration of torsion effects during the design process because torsion effects are elastically considered, while most of the seismic code design methodology is based on the safety level earthquake (EQ). This paper shows that for a special class of buildings, the reduction in the building strength resulting from inelastic torsion can be obtained using the classical theorems of plastic analysis. By analyzing an auxiliary structure, a simplified formula for the reduction in strength due to inelastic torsion is obtained. Using this simplified formula, guidelines to control inelastic torsion during preliminary seismic design are offered.
- Published
- 1995
49. The theory of torsion of elastic noncircular cylinders under large deformations
- Author
-
Zubov, L.M. and Bogachkova, L.U.
- Subjects
Torsion -- Analysis ,Boundary value problems -- Numerical solutions ,Bars (Engineering) -- Analysis ,Science and technology - Abstract
A nonlinear theory of prismatic elastic bar torsion with deformation is developed. By the use of the Saint-Venant semi-inverse technique, the problem has been reduced to the two-dimensional boundary value problem for the bar cross-section. Differential balance equations and lateral conditions fit the boundary value solution. Torsion problems for cylinders made of Treloar and Blatz-Ko materials are solved.
- Published
- 1995
50. Torsional vibrations of synchronous motor driven trains using p-method
- Author
-
Chen, W.J.
- Subjects
Synchronous electric motors -- Evaluation ,Torsion -- Analysis ,Finite element method -- Usage ,Science and technology - Abstract
Synchronous motors produce damaging oscillating torques during startup. If the system is not properly analyzed and designed, the torsional excitation can be very destructive. This paper presents a systematic approach to the dynamic analysis of synchronous motor driven rotating machinery. The p-version of the finite element method is used in the formulation of the equations of motion which provides a great deal of simplicity in the modeling process. The convergence is achieved by increasing the polynomial order of the basis functions of the geometric elements. The system damping matrix can be constructed from the element level or can be calculated by specifying the critical damping factors for a given number of modes of interest. A modified Newmark integration method is employed in the nonlinear transient response calculation. The nonlinearity of the flexible resilient couplings can be easily implemented into this direct numerical integration algorithm. The dynamic stiffness and damping of the resilient couplings are updated at each time step to ensure the dynamic equilibrium. Two examples have been employed to illustrate the validity of the proposed algorithm. The effectiveness, accuracy, and simplicity of the use of p-method on the torsional vibration of synchronous motor driven trains are demonstrated in this paper.
- Published
- 1995
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