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Journal articles on the topic 'Torsional stiffness'
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1
Tso, W. K., and C. M. Wong. "An evaluation of the New Zealand code torsional provision." Bulletin of the New Zealand Society for Earthquake Engineering 26, no. 2 (June 30, 1993): 194–207. http://dx.doi.org/10.5459/bnzsee.26.2.194-207.
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This study evaluates the New Zealand torsional provision in the 1984 and 1992 editions of the New Zealand loading code (NZS 4203) based on the inelastic responses of a single mass model having lateral load resisting elements in two orthogonal directions and subjected to bidirectional base excitations. It is shown that for systems having torsional stiffnesses that exceed a minimum value, the provision in NZS 4203:1984 will restrict the ductility demands on the resisting elements no more than those of a similar but torsionally balanced system. This minimum torsional stiffness depends on the structural eccentricity of the system. For systems with torsional stiffness less than the minimum, the stiff edge elements can experience additional ductility demand because the 1984 edition of the Code permits excessive strength reduction on the stiff edge elements. In the 1992 edition, the Code imposes a minimum torsional stiffness of a structure in the farm of edge displacement ratios. With this new requirement, the danger of additional ductility demand on the stiff edge element is eliminated. Therefore, the torsional provision in the current edition will ensure no additional ductility demands on all lateral force elements caused by torsion.
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Wang, Chunjian, Beshah Ayalew, John Adcox, Benoit Dailliez, Tim Rhyne, and Steve Cron. "Self-Excited Torsional Oscillations under Locked-Wheel Braking: Analysis and Experiments." Tire Science and Technology 43, no. 4 (October 1, 2015): 276–96. http://dx.doi.org/10.2346/tire.15.430402.
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ABSTRACT This paper analyzes the effect of tire/vehicle parameters, specifically of tire/suspension torsional stiffnesses, on the stability of self-excited tire torsional oscillations during locked-wheel braking events. Using a torsionally flexible tire-wheel model and a dynamic tire-ground friction model, two system models for tire oscillations are considered: with suspension torsional compliance included in one but excluded in the other. Bifurcation analysis is conducted on both systems to derive the effect of tire/vehicle parameters on the stability. For the system without suspension torsional compliance, it is highlighted that the primary cause of unstable self-excited oscillations is the “Stribeck” effect in tire-ground friction. Based on the parameters obtained experimentally, the bifurcation surface of vehicle velocity with respect to tire/suspension torsional stiffness is also given. The effect of tire/suspension torsional stiffness to the stability of tire torsional oscillation is qualitatively validated via comparisons between locked-wheel braking simulations and experiments with tires with different torsional stiffnesses.
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Pan, Wen-Hao, Chuan-Hao Zhao, Yuan Tian, and Kai-Qi Lin. "Exact Solutions for Torsion and Warping of Axial-Loaded Beam-Columns Based on Matrix Stiffness Method." Nanomaterials 12, no. 3 (February 4, 2022): 538. http://dx.doi.org/10.3390/nano12030538.
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The typically-used element torsional stiffness GJ/L (where G is the shear modulus, J the St. Venant torsion constant, and L the element length) may severely underestimate the torsional stiffness of thin-walled nanostructural members, due to neglecting element warping deformations. In order to investigate the exact element torsional stiffness considering warping deformations, this paper presents a matrix stiffness method for the torsion and warping analysis of beam-columns. The equilibrium analysis of an axial-loaded torsion member is conducted, and the torsion-warping problem is solved based on a general solution of the established governing differential equation for the angle of twist. A dimensionless factor is defined to consider the effect of axial force and St. Venant torsion. The exact element stiffness matrix governing the relationship between the element-end torsion/warping deformations (angle and rate of twist) and the corresponding stress resultants (torque and bimoment) is derived based on a matrix formulation. Based on the matrix stiffness method, the exact element torsional stiffness considering the interaction of torsion and warping is derived for three typical element-end warping conditions. Then, the exact element second-order stiffness matrix of three-dimensional beam-columns is further assembled. Some classical torsion-warping problems are analyzed to demonstrate the established matrix stiffness method.
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Li, Hong Yan, and Xiu Li Li. "Finite Element Analysis of the Cylindrical Helical Torsional Spring." Applied Mechanics and Materials 397-400 (September 2013): 633–36. http://dx.doi.org/10.4028/www.scientific.net/amm.397-400.633.
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Stress of the cylindrical helical torsion spring is researched with finite element method when torsional degree changes. For spring has great resilience, large deformation effect is considered in the simulations. Analysis on the stiffness shows that the model built is credible, although torsional stiffness is not constant for large torsional angle, the strength is enough whose variation trend is consistent with the spring stiffness with different working torsional angle.
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Kasti, Najib A. "Zigzag Carbon Nanotubes under Simple Torsion – Structural Mechanics Formulation." Advanced Materials Research 452-453 (January 2012): 1139–43. http://dx.doi.org/10.4028/www.scientific.net/amr.452-453.1139.
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When using structural mechanics to study the deformation of carbon nanotubes (CNTs), one has to pick the structural mechanics properties that are equivalent to the molecular mechanics properties. In a previous publication [1], we have determined the relation between the bending stiffness EI/a used in structural mechanics and the bond bending stiffness C used in molecular mechanics for zigzag carbon nanotubes under simple tension. This paper extends the concept and determines the corresponding relation for simple torsion. We show that the relation obtained is different than that of simple tension; in simple torsion, EI/a is load and chirality dependent. However, for the particular case of a graphene sheet, simple tension and torsion lead to the same value of EI/a, namely C/2. We also include the structural mechanics deformation of the tube that accounts for axial, bending and torsional structural stiffnesses. Unlike simple tension, the deformation in the case of simple torsion has the axial stiffness coupled to the bending and torsional stiffnesses.
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Mohamed, Osama Ahmed, and Mohamed Sherif Mehana. "Assessment of Accidental Torsion in Building Structures Using Static and Dynamic Analysis Procedures." Applied Sciences 10, no. 16 (August 9, 2020): 5509. http://dx.doi.org/10.3390/app10165509.
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This article presents the findings of a study on assessment of the increase in building’s response due to accidental torsion when subjected to seismic forces. Critical stiffness and geometrical parameters that define buildings torsional response are examined including: (1) the ratio, Ω, between uncoupled torsional frequency ωθ to uncoupled translation frequencies in the direction of ground motion ωx or ωy, (2) floor plan aspect ratio, b/r, which is a function of the floor dimension and radius of gyration. The increased response is assessed on symmetric multi-storey buildings using both static and dynamic analysis methods specified by ASCE-7 and considering parameters affecting the torsional response. It was concluded that static and dynamic analysis procedures predict different accidental torsion responses. Static analysis based on the Equivalent Lateral Force (ELF) method predicts more conservative accidental torsions responses for flexible structures with Ω < 0.7~0.80, while the responses are less conservative for stiffer buildings. The conservativism in static analysis method is attributed to the response amplification factor, Ax. Floor plans and their lateral support system having frequency ratio Ω = 1 will also have a torsional radius equal to radius of gyration, and will experience drop in torsional response relative to more torsionally flexible buildings. This article presents a procedure to overcome the shortcomings of static and dynamic analysis procedures in terms of estimating accidental torsion response of symmetric building structures.
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Kurdi, Ojo, Mohd Shukri Yob, Awisqarni Haji Ishamuddin, Agus Suprihanto, Susilo Adi Widyanto, Dwi Basuki Wibowo, and Ian Yulianti. "Design and fabrication of a twist fixture to measure torsional stiffness of a pick up chassis." MATEC Web of Conferences 159 (2018): 02030. http://dx.doi.org/10.1051/matecconf/201815902030.
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Torsional stiffness is important parameter of chassis that affect the handling performance of chassis. Torsional stiffness can be determined using Finite Element Method (FEM) in early stage design of its. In order to validate the FEM result, experimental work needs to be done. The fixture has been design in simpler stucture, flexible for any kind of chassis and using a simple measurement’s equipment such as dial indicator and load cell. Twist fixture has been designed for measuring of torsional stiffness of TATA cab chassis indirectly. The fixture measured the deflection caused by torsion subjected to the chassis. The torsional stiffness was calculated based on measured displacement of chassis. The result of comparison shows that the experimental results in agreement with the simulation results. Therefore, the simulation results of TATA cab chassis model are valid.
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Humar, JagMohan, Soheil Yavari, and Murat Saatcioglu. "Design for forces induced by seismic torsion." Canadian Journal of Civil Engineering 30, no. 2 (April 1, 2003): 328–37. http://dx.doi.org/10.1139/l02-029.
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Eccentricities between the centres of rigidity and centres of mass in a building cause torsional motion during an earthquake. Seismic torsion leads to increased displacement at the extremes of the building and may cause distress in the lateral load-resisting elements located at the edges, particularly in buildings that are torsionally flexible. For an equivalent static load method of design against torsion, the 1995 National Building Code of Canada specifies values of the eccentricity of points through which the inertia forces of an earthquake should be applied. In general, the code requirements are quite conservative. They do not place any restriction on the torsional flexibility, however. New proposals for 2005 edition of the code which simplify the design eccentricity expressions and remove some of the unnecessary conservatism are described. The new proposals will require that a dynamic analysis method of design be used when the torsional flexibility of the building is large. Results of analytical studies, which show that the new proposals would lead to satisfactory design, are presented.Key words: torsional response to earthquake, natural torsion, accidental torsion, design for torsion, National Building Code of Canada, interdependence of strength and stiffness.
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Jin, Guanghu, Wei Ren, and Rupeng Zhu. "Influence of torsional stiffness on load sharing coefficient of a power split drive system." MATEC Web of Conferences 211 (2018): 17002. http://dx.doi.org/10.1051/matecconf/201821117002.
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A dynamic model of power split transmission system with face gear and cylindrical gear is established. The factors including time-varying mesh stiffness, torsional stiffness, supporting stiffness, and clearance are considered in the model. The influence of the torsional stiffness of compound gear shaft on the load sharing coefficient is analyzed. The results show that the influence of the torsional stiffness of the compound gear shaft is obvious. Because the torsional stiffness of the output gear components is larger and the torsional stiffness of the input gear is smaller, so the input stage's deformation coordination ability is strong. Therefore, with the increase of the torsional stiffness of the compound gear shaft, the load sharing coefficient of the power input stages is improved, but the load sharing coefficient of the split torque stages and power confluence stages is worse. Hence, the torsional stiffness ratio of the transmission shaft should be rationally allocated under the condition that the torsional stiffness of the compound shaft is small.
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Kurdi, Ojo, Roslan Abdul Rahman, and Pakharuddin Mohd Samin. "Optimization of Heavy Duty Truck Chassis Design by Considering Torsional Stiffness and Mass of the Structure." Applied Mechanics and Materials 554 (June 2014): 459–63. http://dx.doi.org/10.4028/www.scientific.net/amm.554.459.
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The torsional stiffness is one of the most important properties of chassis that significantly affect its dynamic characteristics such as handling and rollover. The torsional stiffness is desired to be as high as possible since low torsional stiffness may cause resonance or vibration. There are several types of heavy duty truck chassis that used in Malaysia and no information about the torsional stiffness magnitude of it. In this work, the torsional stiffness of several existing types of heavy duty truck chassis and some modified types, namely: arc model, block model, hole model, multi holes model and fully block model are determined using finite element method. The torsional stiffness of several chassis was compared together with the weight comparison in order to get the best design of chassis that has high torsional stiffness and low weight. Based on the simulation result, the multi holes model is the best design due to the highest of torsional stiffness and the lowest mass.
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Bazhenov, E. E., S. K. Bujnachev, and A. N. Kustovskij. "Limits of applicability of the standard method for estimating the torsional rigidity of spatial frames of buggy vehicle." Izvestiya MGTU MAMI 12, no. 4 (December 15, 2018): 55–60. http://dx.doi.org/10.17816/2074-0530-66839.
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The article provides an assessment of the limits of applicability of the standard methodology for estimating the torsional rigidity of spatial rod-bearing systems of automobiles. Torsional stiffness, as shown by numerous studies and practices, is one of the most important indicators of the carrying capacity of vehicle bodies (frames) of all types of vehicles - including such highly specialized ones as buggy. The authors show on the example of the bearing structure of an off-road vehicle of the “buggy” class that the general application approach to the assessment of the torsional rigidity of the bearing systems using torsion deflection stumbles upon limitations when it comes to spatial frames of complex construction. These restrictions are dictated by the difference in stiffness between design zones (zones should be understood as the floor area, the waist area and the roof area), which is reflected in the significantly different distribution of displacements in them. As a result, it becomes impossible to unequivocally give an opinion on the torsional rigidity of the frame using torsion deflection, since it is impossible to select a reference point in any of the zones (or the entire zone) to adequately describe the torsional rigidity of the whole structure (or a separate substructure). In this regard, the authors proposed the limits of applicability of the traditional method for estimating the torsional stiffness of a spatial core structure, and also proposed a method for overcoming these difficulties encountered when trying to assess the torsional stiffness of the supporting structure. The object of the research is a typical spatial frame of an all-terrain automobile of the D2 class buggy.
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Wei, Zhan Guo. "Torsional Vibration Dynamics Modeling and Simulation Research on Harvester." Applied Mechanics and Materials 443 (October 2013): 160–63. http://dx.doi.org/10.4028/www.scientific.net/amm.443.160.
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building picking mechanical torsional vibration dynamics model, carries on the equivalent moment of inertia, equivalent torsional stiffness calculation, torsional system intrinsic characteristics are analyzed, and the programming, the Harvester power transmission system of each order natural frequency and engine low harmonic times incentive relations, so as to make the vehicle torsion effect effectively restrain.
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Heinrich, Dieter, Martin Mössner, Peter Kaps, and Werner Nachbauer. "A Parameter Optimization Method to Determine Ski Stiffness Properties From Ski Deformation Data." Journal of Applied Biomechanics 27, no. 1 (February 2011): 81–86. http://dx.doi.org/10.1123/jab.27.1.81.
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The deformation of skis and the contact pressure between skis and snow are crucial factors for carved turns in alpine skiing. The purpose of the current study was to develop and to evaluate an optimization method to determine the bending and torsional stiffness that lead to a given bending and torsional deflection of the ski. Euler-Bernoulli beam theory and classical torsion theory were applied to model the deformation of the ski. Bending and torsional stiffness were approximated as linear combinations of B-splines. To compute the unknown coefficients, a parameter optimization problem was formulated and successfully solved by multiple shooting and least squares data fitting. The proposed optimization method was evaluated based on ski stiffness data and ski deformation data taken from a recently published simulation study. The ski deformation data were used as input data to the optimization method. The optimization method was capable of successfully reproducing the shape of the original bending and torsional stiffness data of the ski with a root mean square error below 1 N m2. In conclusion, the proposed computational method offers the possibility to calculate ski stiffness properties with respect to a given ski deformation.
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Han, Lin, Lixin Xu, and Fujun Wang. "Study on torsional stiffness of transmission employed in a rotary table." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 230, no. 19 (August 8, 2016): 3541–55. http://dx.doi.org/10.1177/0954406215613116.
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Torsional stiffness of a rotary table plays an important role in the static and dynamic characteristics of a rotary feed drive system. This paper proposes an effective approach to estimate the torsional stiffness of a worm geared transmission usually employed in rotary table. First, the stiffness models of each component used in the transmission are extracted. Then, an expression for the coefficient relating angular displacements is derived and a general torsional stiffness model for the rotary feed drive is developed, taking the time-varying mesh stiffness into account. Finally, a stiffness test scheme is presented and conducted to verify the proposed stiffness model. Furthermore, the influences of the gear’s parameters on the resultant torsional stiffness are investigated based on the developed model. Results indicate the necessity to incorporate a time-varying mesh stiffness when the torsional stiffness of the rotary table is under estimation. Also, a high-frequency variation in profile of torsional stiffness is induced by the mesh stiffness of gear pairs at the high-speed stage. Parametric studies show that tooth width and number of teeth of the driven gear at low-speed stage are more sensitive to stiffness than those at high-speed stage. However, the number of teeth of the driving gears introduces different effects onto the torsional stiffness. The presented model can be used to estimate the torsional stiffness of a rotary feed system efficiently, especially during the preliminary design stage.
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Kinnunen, Kalle, Sampo Laine, Tuomas Tiainen, and Raine Viitala. "Method for Adjusting Torsional Natural Frequencies of Powertrains with Novel Coupling Design." Machines 10, no. 3 (February 22, 2022): 162. http://dx.doi.org/10.3390/machines10030162.
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Torsional vibrations are inherently present in every rotating powertrain. In resonant conditions, torsional vibrations can be significantly amplified. A typical method to reduce the torsional vibration particularly at resonance is to modify the torsional natural frequencies with the component design. Commonly, a straightforward method for the modification is the adjustment of the torsional stiffness of a coupling. This study presents a method to modify the torsional natural frequencies using a coupling design with continuously adjustable torsional stiffness. The presented coupling design is investigated with torsional analysis and experimental measurements. Torsional analysis was utilized to predict the effects of varying the coupling stiffness to the torsional natural frequencies of a powertrain. The experimental measurements were conducted by attaching the adjustable stiffness coupling to the powertrain and measuring the change in the torsional natural frequencies while the torsional stiffness of the coupling was adjusted. The torsional natural frequencies were determined from the measurements by identifying the resonance induced torsional vibrations from the vibration response of the powertrain. The torsional vibrations were excited to the system by a load motor. The measurements showed that the first torsional natural frequency of the powertrain changed from 15.6 Hz to 43.0 Hz as the torsional stiffness of the coupling was adjusted. The results of the torsional analysis and the experimental measurements were compared to determine the performance of the realized coupling. The results indicated that the torsional natural frequencies determined by torsional analysis agree well with the experimentally measured results. The prediction errors were generally below ±5%, which is typically considered as a margin for accurate torsional analysis.
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Ashour, Samir A., Sabry A. Shihata, Ali A. Akhtaruzaman, and Faisal F. Wafa. "Prestressed high-strength concrete beams under torsion and bending." Canadian Journal of Civil Engineering 26, no. 2 (April 1, 1999): 197–207. http://dx.doi.org/10.1139/l98-054.
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Test results of 16 rectangular prestressed high-strength concrete beams subjected to the combined action of torsion and bending are presented. The major variables were the ratio of torsion to the bending moment (T/M) and the prestressing level. The beams were subjected to two levels of prestressing, corresponding to 0.05fc' and 0.10fc', where fc' is the compressive strength of concrete (about 90 MPa). Test results showed that the torque-twist relations for the test beams were approximately linear up to cracking and thereafter became nonlinear. Increasing the T/M ratio and the prestressing level increases both torsional stiffness and strength. Several theoretical methods available in the literature developed for normal-strength concrete were used to predict the torsional strength of the tested high-strength concrete beams. Interaction equations were used along with some other methods to predict the torsional capacity in the presence of a bending moment. Good agreement was observed between the experimental and theoretical results.Key words: beams (supports), bending, cracking, failure, high-strength concrete, interaction diagram, prestressed concrete, stiffness, torsion, torsional strength.
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Chen, Shu Ming, Xue Wei Song, Chuan Liang Shen, Deng Feng Wang, and Wei Li. "Experimental Analysis of Static Stiffness for Vehicle Body in White." Applied Mechanics and Materials 248 (December 2012): 69–73. http://dx.doi.org/10.4028/www.scientific.net/amm.248.69.
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In order to know the static stiffness characteristics of the vehicle body in white, the bending stiffness and torsional stiffness of an automotive body in white were tested on a test bench of the static stiffness of an automotive BIW. The bending stiffness and bending deformation of the bottom of the BIW were determined. Also, the torsional stiffness and torsional deformation of the bottom of the BIW were obtained. The fitting curves and equations between loading torque and torsional angle were acquired at clockwise and counterclockwise loading, respectively.
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Garbowski, Tomasz, Tomasz Gajewski, and Jakub Krzysztof Grabski. "Torsional and Transversal Stiffness of Orthotropic Sandwich Panels." Materials 13, no. 21 (November 6, 2020): 5016. http://dx.doi.org/10.3390/ma13215016.
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In the present work, an analytical equation describing the plate torsion test taking into account the transverse shear stiffness in sandwich plates is derived and numerically validated. Transverse shear becomes an important component if the analyzed plate or shell is thick with respect to the in-plane dimensions and/or its core has significantly lower stiffness than the outer faces. The popular example of such a sandwich plate is a corrugated cardboard, widely used in the packaging industry. The flat layers of a corrugated board are usually made of thicker (stronger) material than that used for the corrugated layer, the role of which is rather to keep the outer layers at a certain distance, to ensure high bending stiffness of the plate. However, the soft core of such a plate usually has a low transverse shear stiffness, which is often not considered in the plate analysis. Such simplification may lead to significant calculation errors. The paper presents the generalization of the Reissner’s analytical formula, which describes the torsional stiffness of the plate sample including two transverse shear stiffnesses. The paper also presents the implementation of the numerical model of the plate torsion test including the transverse shear stiffnesses. Both approaches are compared with each other on a wide range of material parameters and different aspect ratios of the specimen. It has been proved that both analytical and numerical formulations lead to an identical result. Finally, the performance of presented formulations is compared with other numerical models using commercial implementation of various Reissner–Mindlin shell elements and other analytical formulas from the literature. The comparison shows good agreement of presented theory and numerical implementation with other existing approaches.
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Canale, Giacomo, Felice Rubino, Paul M. Weaver, Roberto Citarella, and Angelo Maligno. "Simplified and Accurate Stiffness of a Prismatic Anisotropic Thin-Walled Box." Open Mechanical Engineering Journal 12, no. 1 (February 14, 2018): 1–20. http://dx.doi.org/10.2174/1874155x01812010001.
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Background:Beam models have been proven effective in the preliminary analysis and design of aerospace structures. Accurate cross sectional stiffness constants are however needed, especially when dealing with bending, torsion and bend-twist coupling deformations. Several models have been proposed in the literature, even recently, but a lack of precision may be found when dealing with a high level of anisotropy and different lay-ups.Objective:A simplified analytical model is proposed to evaluate bending and torsional stiffness of a prismatic, anisotropic, thin-walled box. The proposed model is an extension of the model proposed by Lemanski and Weaver for the evaluation of the bend-twist coupling constant.Methods:Bending and torsional stiffness are derived analytically by using physical reasoning and by applying bending and torsional stiffness mathematic definition. Unitary deformations have been applied when evaluation forces and moments arising on the cross section.Results:Good accuracy has been obtained for structures with different geometries and lay-ups. The model has been validated with respect to finite element analysis. Numerical results are commented upon and compared with other models presented in literature.Conclusion:For cross sections with a high level of anisotropy, the accuracy of the proposed formulation is within 2% for bending stiffness and 6% for torsional stiffness. The percentage of error is further reduced for more realistic geometries and lay-ups.The proposed formulation gives accurate results for different dimensions and length rations of horizontal and vertical walls.
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Singhanart, Thanyarat, Thammongkol Sangmanacharoen, Wasin Tocharoen, and Phongpakkan Danwibun. "Space Frame Analysis, Design, and Testing for Electric Vehicle Formula." Applied Mechanics and Materials 619 (August 2014): 183–87. http://dx.doi.org/10.4028/www.scientific.net/amm.619.183.
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The objective of this paper is to design, analyze, and test the space frame for electric vehicle with comparison to the engine type. Therefore, in order to design the electric vehicle formula, the same requirements with some changes are considered. The space frame is designed to suit with the electric vehicle and then finite element analysis is used to determine the torsional stiffness of the frame which is verified by the torsional test. Initially, the required torsional stiffness for the electric car is 1350 Nm/deg and the mass is set to be not more than 40 kg. The numerical results and the experimental results for torsional stiffness are 960 Nm/deg and 1218 Nm/deg, respectively. Therefore, the torsional stiffness is about 25% under-predicted; anyway it can be used to predict the torsional stiffness of the frame. Due to some changes must be performed, therefore the modified frame is re-analyzed with the torsional stiffness of 1389 Nm/deg which is less than the revised required car’s torsional stiffness of 1404 Nm/deg. Anyway, the torsional stiffness of frame with battery’s case can meet the requirement. The mass of the modified frame is 50 kg which is larger than required mass due to selected sizes of steel tubes. In conclusion, the space frame can be designed and the mass can be improved further by reducing the sizes.
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Hutcheson, K. D., S. E. Elder, and J. R. Butler. "Comparison of double locking plate constructs with single non-locking plate constructs in single cycle to failure in bending and torsion." Veterinary and Comparative Orthopaedics and Traumatology 28, no. 04 (2015): 234–39. http://dx.doi.org/10.3415/vcot-14-09-0149.
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SummaryObjective: To evaluate the biomechanical properties of single 3.5 mm broad dynamic compression plate (DCP) and double 3.5 mm String-of-Pearls (SOP) plate constructs in single-cycle bending and torsion. We hypothesized that the double SOP construct would outperform the broad DCP in both bending and torsional testing.Methods: Broad DCP plates and double 3.5 mm SOP plates were secured to a previously validated bone model in an effort to simulate bridging osteosynthesis. Constructs were tested in both four-point bending and torsional testing.Results: The double SOP constructs had significantly greater bending stiffness, bending strength, bending structural stiffness, and torsional stiffness when compared to the broad DCP constructs. The single broad DCP constructs had significantly higher yield torque and yield angles during torsional testing.Clinical relevance: Although the in vitro mechanical performance of the double SOP construct was significantly greater than the single broad DCP constructs under bending loads, the actual differences were small. Various patient, fracture, and implant factors must be considered when choosing an appropriate implant for fracture fixation.
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Lu, C. L., T. X. Wu, J. G. Yu, and Q. T. Ye. "On torsional stiffness and natural frequency of bellows." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 218, no. 3 (March 1, 2004): 263–71. http://dx.doi.org/10.1243/095440604322900390.
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Simplified formulae for torsional natural frequencies of bellows are developed using an equivalent thin-walled pipe model. To do this the torsional stiffness of bellows needs to be worked out. The torsional stiffness of bellows is determined using Chien's integration method. Accordingly, the Expansion Joint Manufactures Association (EJMA) formula for torsional stiffness calculation is modified using two different equivalent radii. The torsional natural frequencies of bellows are calculated using the simplified formulae based on the equivalent thin-walled pipe model and the modified formulae for torsional stiffness of bellows. The results from the simplified formuale are verified by those from a finite element (FE) model and good agreement is shown between the simplified formulae and the FE model.
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Smeathers, J. E. "Measurement of Flexural and Torsional Stiffness for the Human Torso in Vivo; Implications for Scoliosis." Engineering in Medicine 16, no. 4 (October 1987): 237–40. http://dx.doi.org/10.1243/emed_jour_1987_016_053_02.
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Voluntary oscillations of the human torso are analysed using engineering beam theory to estimate the flexural and torsional stiffness of the back. Antero-posterior and lateral flexural stiffness are measured as well as the torsional stiffness for both relaxed conditions and at maximum voluntary exertion. The ratio of flexural stiffness in two mutually perpendicular planes is a guide to the torsional stability of a beam in bending. These criteria are used to assess the torsional stability of the human torso when subjected to large bending moments.
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Silveira, Marcos, Bento R. Pontes, and José M. Balthazar. "Influence of Nonlinear Stiffness on the Dynamics of a Slender Elastic Beam under Torsional Oscillations." Applied Mechanics and Materials 706 (December 2014): 159–69. http://dx.doi.org/10.4028/www.scientific.net/amm.706.159.
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This study focuses on analysing the effects of nonlinear torsional stiffness on the dynam-ics of a slender elastic beam under torsional oscillations, which can be subject to helical buckling.The helical buckling of an elastic beam confined in a cylinder is relevant to many applications. Someexamples include oil drilling, medical cateters and even the conformation and functioning of DNAmolecules. A recent study showed that the formation of the helical configuration is a result of onlythe torsional load, confirming that there is a different path to helical buckling which is not related tothe sinusoidal buckling, stressing the importance of the geometrical behaviour of the beam. A lowdimensional model of an elastic beam under torsional oscillations is used to analyse its dynamical be-haviour with different stiffness characteristics, which are present before and after the helical buckling.Hardening and softening characteristics are present, as the effects of torsion and bending are coupled.With the use of numerical algorithms applied to nonlinear dynamics, such as bifurcation diagramsand basins of attraction, it is shown that the nonlinear stiffness can shift the bifurcations and inducechanges in the stability of the desirable and undesirable solutions. Therefore, the proper modellingof these stiffness nonlinearities seems to be important for a better understanding of the dynamicalbehaviour of such beams
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Afonso, F., G. Leal, J. Vale, É. Oliveira, F. Lau, and A. Suleman. "The effect of stiffness and geometric parameters on the nonlinear aeroelastic performance of high aspect ratio wings." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 231, no. 10 (November 25, 2016): 1824–50. http://dx.doi.org/10.1177/0954410016675893.
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The increase in wing aspect ratio is gaining interest among aircraft designers in conventional and joined-wing configurations due to the higher lift-to-drag ratios and longer ranges. However, current transport aircraft have relatively small aspect ratios due their increased structural stiffness. The more flexible the wing is more prone to higher deflections under the same operating condition, which may result in a geometrical nonlinear behavior. This nonlinear effect can lead to the occurrence of aeroelastic instabilities such as flutter sooner than in an equivalent stiffer wing. In this work, the effect of important stiffness (inertia ratio and torsional stiffness) and geometric (sweep and dihedral angles) design parameters on aeroelastic performance of a rectangular high aspect ratio wing model is assessed. The torsional stiffness was observed to present a higher influence on the flutter speed than the inertia ratio. Here, the decrease of the inertia ratio and the increase of the torsional stiffness results in higher flutter and divergence speeds. With respect to the geometric parameters, it was observed that neither the sweep angle nor the dihedral angle variations caused a substantial influence on the flutter speed, which is mainly supported by the resulting smaller variations in torsion and bending stiffness due to the geometric changes.
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AKASAKA, T., M. KATOH, and A. NODA. "Torsional stiffness of steel cords." Journal of the Japan Society for Composite Materials 14, no. 6 (1988): 228–32. http://dx.doi.org/10.6089/jscm.14.228.
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Kinnunen, K., P. Kiviluoma, S. Laine, A. Seppänen, T. Tiainen, T. Turrin, R. Viitala, and R. Viitala. "Coupling with adjustable torsional stiffness." Proceedings of the Estonian Academy of Sciences 70, no. 4 (2021): 470. http://dx.doi.org/10.3176/proc.2021.4.14.
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Macikowski, Krzysztof, Bogdan Warda, Grzegorz Mitukiewicz, Zlatina Dimitrova, and Damian Batory. "Change in the Torsional Stiffness of Rectangular Profiles under Bending Stress." Materials 15, no. 7 (March 31, 2022): 2567. http://dx.doi.org/10.3390/ma15072567.
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This article presents the results of research on the change in torsional stiffness of two rectangular profiles, arranged one on top of the other, which were permanently connected at their ends. The flat bars were expanded in the middle of their active length. The test involved determining the increase in the stiffness of a twisted test set before and after expanding. The authors present an analysis of the structure load and compare the results of tests carried out using analytical (for selected cases), numerical and experimental methods, obtaining satisfactory compliance. The analytical calculations included the influence of limited deplanation in the areas of the profile’s restraint. The ANSYS package software was used for calculations with the Finite Element Method. A change in the stiffness increase index at torsion was determined. The obtained results showed that expanding the test sets in their middle causes an increase in torsional stiffness, which is strongly dependent on the design parameters such as bending deflection, torsion angle and dimensions of the cross-section of the flat bar in the package.
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Chen, Gongfa, Zongchao Liu, Yong Zhang, Jiqiao Zhang, Fangsen Cui, and Minglong Xu. "Biomechanical Assessment for Healing Progression of Fractured Long Bones: Comparisons of Various Methods Using Beam Models." International Journal of Applied Mechanics 08, no. 06 (September 2016): 1650074. http://dx.doi.org/10.1142/s1758825116500745.
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Measurements of various effective stiffnesses have been suggested as non-invasive biomechanical methods to assess healing status of a fractured long bone. This paper has compared the sensitivities of five assessment methods for fracture healing of long bones: torsion, compression, 3-point bending, 4-point bending and cantilever bending. A fractured human femur is modeled by an Euler beam and Castigliano’s theorem is used to obtain the effective stiffnesses of the fractured bone. The variations of the effective stiffnesses of the fractured bone with the healing status of the callus have been investigated. The healing process of the callus is represented by gradual increases of the Young’s modulus. The callus is divided into multiple regions. The narrowing process of the fracture gap is characterized by assigning different Young’s modulus for different regions. Our findings showed that torsional, compressional, and bending stiffnesses all perform similarly with respect to the healing process. Before the rapid increase, all effective stiffness curves show a substantial creeping stage which corresponds to the narrowing process of the fracture gap. A higher value of them indicates bony bridging of healing callus. The effective stiffnesses for cantilever bending and 3-point bending are more sensitive to the fracture location, while torsional and compressional stiffness are independent from the fracture location.
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He, Xi, and Yu Jiong Gu. "Study on the Method of Online Adaptive Adjustment Method for Torsional Vibration Model of Turbine Shafting." Applied Mechanics and Materials 602-605 (August 2014): 684–88. http://dx.doi.org/10.4028/www.scientific.net/amm.602-605.684.
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The accuracy of safety analysis can be guaranteed when the torsional vibration model is adjusted online according to the inherent characteristics of the torsional vibration of the shafting. Torsional stiffness of model is set as the object for adjustment. The sensitivity of the natural frequency of torsional vibration model to structure parameters is analyzed and the sensitivity of the natural frequency of torsional vibration model to torsional stiffness is calculated. According to the difference between the natural frequency of torsional vibration which is get from actual shafting and the natural frequency of torsional vibration which is calculated by torsional vibration model, the adaptive adjustment of the torsional stiffness of mode is solved by using the method of Taylor expansion which ignore two times or more correction. The logic structure of the adaptive process of torsional vibration model is designed and the online adaptive function of torsional vibration model is implemented in the torsional vibration safety and analysis system. The torsional vibration modelof 1000WM turbogenerator is used as an example and the accuracy of the method is verified.
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Chang, Le, Yucheng Huang, Najeeb Ullah, Ling Zhu, Zhenyu Lv, and Yuanlin Jing. "Torsional Stiffness Analysis Based on Lagrangian Method for Precision Rotary Vector Reducer with Involute Variable Tooth Thickness." Applied Sciences 12, no. 14 (July 11, 2022): 7003. http://dx.doi.org/10.3390/app12147003.
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The precision rotary vector reducer with involute variable tooth thickness (PRVT) is a high-performance precision transmission device, which is very suitable for aerospace, medical machinery, industrial robots, automation equipment, and other fields, and its torsional stiffness is an important performance index. This paper establishes a dynamics model of the whole machine based on the Lagrangian method by considering gear meshing stiffness, damping, and machining errors, and the influence of different machining errors on dynamic torsional stiffness is studied. The results show that increasing the distribution circle radius error of the crankshaft, the crank angle error and the distribution circle radius error of the crankshaft bearing hole on the carrier will cause the peak-to-peak torsional stiffness to increase. Therefore, the machining errors should be controlled within a reasonable range to improve the whole machine’s stability. An increase in the crankshaft bearing hole rotation error on the No. 1 beveloid gear has no notable impact on the peak-to-peak value and the average value of the torsional stiffness. Similarly, the rotation angle error of the crankshaft bearing hole on the No. 1 carrier has no significant effect on the torsional stiffness. The research results provide a useful reference for the torsional stiffness analysis of PRVT.
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Lee, Hyoungwook, and Chul-Su Kim. "Prediction of Ply Angles of Air Springs According to Airbag Positions and Their Effects on Lateral and Torsional Stiffness." Applied Sciences 12, no. 22 (November 21, 2022): 11815. http://dx.doi.org/10.3390/app122211815.
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The stiffness in various directions of air springs have a great influence on the stability of high-speed trains. Due to the change in the bogie structure, the required functions of the air springs have also diversified, and the damping of various loading modes such as vertical, lateral, and torsional movements is emerging as important. The stiffnesses are affected by the shape of the air bag, the material, and the ply angles. In this paper, the relationship between the ply angle and the radial position is proposed by equations from deformation modes. The variable angles in the plies were compared and demonstrated in air-spring analysis using the rebar elements. The vertical, lateral, and torsional stiffness of air springs without auxiliary springs were compared between constant ply angles and variable ply angles with respect to the positions. When mainly dealing with the vertical stiffness, the effect of the angle variation was small; however, it was found that it had a large effect of more than 24% and 30% on the stiffness in the lateral direction and torsional direction, respectively.
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Parsian, Amir, Mahdi Eynian, Martin Magnevall, and Tomas Beno. "Minimizing the Negative Effects of Coolant Channels on the Torsional and Torsional-Axial Stiffness of Drills." Metals 11, no. 9 (September 16, 2021): 1473. http://dx.doi.org/10.3390/met11091473.
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Coolant channels allow internal coolant delivery to the cutting region and significantly improve drilling, but these channels also reduce the torsional and torsional-axial stiffness of the drills. Such a reduction in stiffness can degrade the quality of the drilled holes. The evacuation of cutting chips and the delivery of the cutting fluid put strict geometrical restrictions on the cross-section design of the drill. This necessitates careful selection and optimization of features such as the geometry of the coolant channels. This paper presents a new method that uses Prandtl’s stress function to predict the torsional and torsional-axial stiffness values. Using this method drills with one central channel are compared to those with two eccentric coolant channels, which shows that with the same cross-section area, the reduction of axial and torsional-axial stiffness is notably smaller for the design with two eccentric channels compared to a single central channel. The stress function method is further used to select the appropriate location of the eccentric coolant channels to minimize the loss of torsional and torsional-axial stiffness. These results are verified by comparison to the results of three-dimensional finite element analyses.
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Cheng, Zhi Hui, and Chao Zhang. "Calculation of Torsional Stiffness of Conductor and its Influence on the Stability of Motion." Applied Mechanics and Materials 680 (October 2014): 233–36. http://dx.doi.org/10.4028/www.scientific.net/amm.680.233.
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In galloping, reverse split wire plays an important role in. Through the study of split change sub conductor length of wire twisting motion estimation, the wire tension change caused by the torsion of sub conductors; besides considering some of the split wire torsion stiffness of the external factors, but also the influence of torsion wire tension change, caused by the conductor sag, line height worse, we deduced the general formula to calculate the new conductor spacer system torsional stiffness.
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Liu, Chun Jie, and Bing Shou Zhu. "Development of a Measuring System for Stiffness Evaluation of Micro Torsion Bar." Applied Mechanics and Materials 33 (October 2010): 190–94. http://dx.doi.org/10.4028/www.scientific.net/amm.33.190.
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For the micro torsion bar used in inertial navigation, the torsional stiffness should be evaluated precisely. A computer-controlled instrument for stiffness measurement based on static measuring principle was introduced for variant section micro bars, The main hardware of the system includes a precision motorized rotary stage and a torsion sensor. The stepping resolution of angular displacement is 0.00250, the measurement accuracy of moment is 0.05mN•m. The measurement software was programmed on the LabVIEW platform for virtual instrument. The measuring experiments indicate the device can be used for automatic testing of stiffness of the torsion bars with high accuracy and efficiency.
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KAŠŠAY, Peter, and Matej URBANSKÝ. "NEW DESIGNS OF VARIABLE STIFFNESS COUPLINGS." Scientific Journal of Silesian University of Technology. Series Transport 117 (December 1, 2022): 91–101. http://dx.doi.org/10.20858/sjsutst.2022.117.6.
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Flexible couplings are widely used in mechanical drives of transport and other machines. A fundamental function of flexible shaft couplings regarding torsional vibration is the optimum tuning of torsional oscillating mechanical systems. At the authors’ workplace, the focus is on the research and design of pneumatic couplings, where the torque is transmitted mainly by compressed gas (air) in their pneumatic flexible elements. The primary advantage of these couplings is that their mechanical properties can be quickly and effectively adjusted, especially the dynamic torsional stiffness, by air pressure change directly while the mechanical system is running. This allows us “to tune” the properties of the pneumatic coupling according to the current parameters of the machine drive to avoid resonance and minimize torsional vibration. Therefore, we tend to refer to them as “pneumatic tuners of torsional vibration”. This paper aims to present two new types of these “pneumatic tuners” that were recently granted patent protections, namely “Pneumatic flexible shaft coupling with hose flexible element” and “Drum pneumatic flexible shaft coupling”. Because these pneumatic tuners are not in practical use yet, this paper describes only their design and supposed benefits.
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Wu, Chao, Yun Fei Peng, Chao Xiang, Xu Yao Mao, Jun Hua Hu, and Yi Ou Liu. "Static Torsional Stiffness Computation of Circumferential Arc Spring Dual Mass Flywheel." Advanced Materials Research 1065-1069 (December 2014): 2080–85. http://dx.doi.org/10.4028/www.scientific.net/amr.1065-1069.2080.
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The iterative formulas of spring forces for Circumferential Arc Spring Dual Mass Flywheel (DMF-CS) were derived by discrete method, involving friction forces. The computation program was designed, and the curves illustrating transmitted torques over deformation angles of the outer and inner arc springs were plotted, which showed linear torque behavior. Thus two stages of torsional stiffness of DMF-CS were figured out to be 465.9923Nm/rad and 631.7980Nm/rad. The two stages of torsional stiffness without friction forces were calculated by this method, which were 434.6408Nm/rad and 591.3652Nm/rad. The experiment of static torque characteristic of DMF-CS was completed, obtaining the experimental torsional stiffness, which were 455.9923Nm/rad and 620.9412Nm/rad. Comparing the above values of torsional stiffness, the values with friction forces show more precise than ones without friction forces, and the values without friction forces are smallest. The results show that the friction forces contribute to the torsional stiffness of DMF-CS.
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Zhang, Hui Bo, Bo Pan, Long Wang, Cheng Wei, Bin Di You, and Yang Zhao. "Non-Linear Dynamic Modeling and Experiment of Harmonic Gear Drive." Applied Mechanics and Materials 668-669 (October 2014): 217–20. http://dx.doi.org/10.4028/www.scientific.net/amm.668-669.217.
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A non-linear torsional vibration model of harmonic gear drive is proposed in the current study. The model includes clearance, nonlinearity torsional stiffness and nonlinearity damping. The clearance model is developed by introducing the piecewise-linear displacement functions. The function of nonlinearity torsional stiffness is obtained by torsional stiffness experimental. The model of nonlinearity damping is used to describe the process of transmission. The non-linear differential equations are solved using Runge-Kutta method. The numerical simulation results show that the influence of nonlinear factors on dynamic behavior, which has chaotic characteristics, is remarkable.
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Akasaka, T., M. Katoh, and H. Makinouchi. "Torsional Stiffness of a Steel-Cord-Reinforced Belt Structure." Tire Science and Technology 17, no. 4 (October 1, 1989): 274–90. http://dx.doi.org/10.2346/1.2141688.
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Abstract Torsional stiffness of its steel-cord-reinforced belt structure affects various characteristics of a radial tire, particularly when it is operating at a camber angle other than zero. We analyzed the torsional stiffness of the belt, with consideration of interply shear deformation, by modeling it with a laminated biased composite strip of unidirectional cord-reinforced rubber (UDCRR) layers. The coupled torsional-extensional deformation of the belt was shown to vanish at the particular bias angle of 54.7°. It is pointed out that the torsional rigidities of constituent steel cords, which were not considered in the classical lamination theory, could increase the twisting stiffness of the belt structure over that predicted by the conventional lamination theory. A test specimen of low aspect ratio was fixed at both ends under torque loading for the tests. Experimental results of the torsional stiffness together with the coupled torsional-extensional strain agreed well with the analytical results.
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ABDULIN, R. R., V. A. PODSHIBNEV, and S. L. SAMSONOVICH. "RESEARCH OF TORSIONAL STIFNESS OF HARMONIC GEAR WITH INTERMEDIATE ROLLING BODIES." Fundamental and Applied Problems of Engineering and Technology 3 (2020): 95–104. http://dx.doi.org/10.33979/2073-7408-2020-341-3-95-104.
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The work is devoted to the urgent problem of developing mechanisms based on wave transmission with intermediate rolling elements (HGRE), which has high specific mass–dimensional parameters, which is especially important for its use in aircraft drive systems. Analytical dependences are obtained that make it possible to calculate the torsional stiffness of HGRE in the multiplier and reduction gear modes. The periodic value of the change in torsional stiffness is determined, due to the relative position of the HGRE elements, namely, the angular position of the wave–former relative to the hard wheel. The results of experimental studies of the torsional stiffness of HGRE are presented, which confirm the periodic value of the change in torsional stiffness of HGRE
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Meng, Yanmei, Yuan Liang, Qinchuan Zhao, and Johnny Qin. "Research on Torsional Property of Body-In-White Based on Square Box Model and Multiobjective Genetic Algorithm." Mathematical Problems in Engineering 2021 (January 23, 2021): 1–13. http://dx.doi.org/10.1155/2021/7826496.
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In order to assess the performance of a vehicle in the conceptual design stage, a square box model was proposed to predict the torsional stiffness and the first-order torsional frequency of Body-in-White. The structure of Body-in-White was decomposed into eight simple structural surfaces, from which a square box model was constructed. Based on the finite element method, modified shear stiffness of each simple structure surface was calculated and the torsional stiffness was obtained. Then, simple structural surfaces of Body-in-White were constructed into an eight degree-of-freedom series spring system to calculate the first-order torsional frequency. Furthermore, a multiobjective genetic algorithm was used to determine the thickness and structural reinforcement of panels with small stiffness, so as to achieve the goal of increasing the stiffness while reducing the mass of the panel. The result shows that the optimal values of thickness are reduced by around 9.9 percent without affecting their performance by the proposed method. Compared to the prediction results obtained with the complicated numerical simulation, the relative error of the square box model in predicting the torsional stiffness is 6.04 percent and in predicting the first-order torsional frequency is 0.95 percent, indicating that the prediction model is effective.
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Zeng, Rong, Zheng Feng Jiang, and Xing Wan. "Frequency Response Analysis of Damped Dual Mass Flywheel." Applied Mechanics and Materials 724 (January 2015): 271–74. http://dx.doi.org/10.4028/www.scientific.net/amm.724.271.
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s:Aiming at circumferential arc spring dual mass flywheel (CSDMF), this paper carries out analysis on the piecewise linear model and calculates the frequency response of damped model under sinusoidal excitation. Being combined with the calculate results, the research respectively analyzes the value of inertia ratio, torsional stiffness and damping parameters. The analysis results show that the greater the damping, inertia ratio of primary and secondary flywheels are, the torsional stiffness, the more obvious vibration damping of the dual mass flywheel would be. To meet the vibration damping requirements, the detail design of the three parameters need to be combined with power train and the torsion characteristic of CSDMF.
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Wang, J., and I. Howard. "The torsional stiffness of involute spur gears." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 218, no. 1 (January 1, 2004): 131–42. http://dx.doi.org/10.1243/095440604322787009.
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This paper presents the results of a detailed analysis of torsional stiffness of a pair of involute spur gears in mesh using finite element methods. Adaptive meshing has been employed within a commercial finite element program to reveal the detailed behaviour in the change over region from single- to double-tooth contact zones and vice versa. Analysis of past gear tooth stiffness models is presented including single- and multitooth models of the individual and combined torsional mesh stiffness. The gear body stiffness has been shown to be a major component of the total mesh stiffness, and a revised method for predicting the combined torsional mesh stiffness is presented. It is further shown tha the mesh stiffness and load sharing ratios will be a function of applied load.
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Li, Wanyou, Zhuoye Chai, Mengqi Wang, Xinhuan Hu, and Yibin Guo. "Online Identification and Verification of the Elastic Coupling Torsional Stiffness." Shock and Vibration 2016 (2016): 1–7. http://dx.doi.org/10.1155/2016/2016432.
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To analyze the torsional vibration of a diesel engine shaft, the torsional stiffness of the flexible coupling is a key kinetic parameter. Since the material properties of the elastic element of the coupling might change after a long-time operation due to the severe working environment or improper use and the variation of such properties will change dynamic feature of the coupling, it will cause a relative large calculation error of torsional vibration to the shaft system. Moreover, the torsional stiffness of the elastic coupling is difficult to be determined, and it is inappropriate to measure this parameter by disassembling the power unit while it is under normal operation. To solve these problems, this paper comes up with a method which combines the torsional vibration test with the calculation of the diesel shafting and uses the inherent characteristics of shaft torsional vibration to identify the dynamic stiffness of the elastic coupling without disassembling the unit. Analysis results show that it is reasonable and feasible to identify the elastic coupling dynamic torsional stiffness with this method and the identified stiffness is accurate. Besides, this method provides a convenient and practical approach to examine the dynamic behavior of the long running elastic coupling.
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Kurdi, Ojo, Roslan Abdul Rahman, Pakharudin Mohd Samin, Mohd Shukri Yob, Nantha Kumar Nadarajan, and Ian Yulianti. "Torsional Stiffness Improvement of Truck Chassis Using Finite Elemen Method." ROTASI 19, no. 2 (July 20, 2017): 76. http://dx.doi.org/10.14710/rotasi.19.2.76-81.
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This thesis deals with a study on the torsional stiffness of existing truck chassis and some others improved models by using finite element method. The objective of this study is to improve the torsional stiffness by design and to provide simulation of the deflection on the chassis. The problem on the chassis is the deflection on the chassis whereas higher displacement will affect the torsional stiffness of the truck. ABAQUS was used as it is a powerful engineering simulation tool based on the finite element method. The magnitude of torsional stiffness for existing and modified models were calculated based on data of deflection of each models which were obtained from the finite element simulation. The multi holes model was choosen as the best proposed model due to the highest of torsional stffness as comparison result among existing and modified models.
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Hao Liu, Cong, Gang Li, Ying Hao Ma, and Xu Guang Yang. "Torsional Stiffness Comparison of Different Tube Cross-Sections of a Formula SAE Car Space Frame." MATEC Web of Conferences 153 (2018): 04002. http://dx.doi.org/10.1051/matecconf/201815304002.
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Since torsional loading and the accompanying deformation of the frame and suspension parts can affect the handling and performance of the car, torsional stiffness is generally thought to be a primary determinant of frame performance for a FSAE car. According to the FSAE Rules, different tube cross-sections are available for some members of a space frame. By finite element simulation, this research compared different tube shapes and thicknesses. Compared with 1.6 mm thickness round tube, square tube with the same wall thickness can improve the torsional stiffness by 23% in test Mode I, and 65% in test Mode II. The 1.2mm thickness square tube also can improve the torsional stiffness by 6% and 39% in test Mode I and Mode II. From these comparisons, it can be found the usage of square tube can improve the frame torsional stiffness efficiently.
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Matsagar, Vasant A., and R. S. Jangid. "Base-Isolated Building with Asymmetries Due to the Isolator Parameters." Advances in Structural Engineering 8, no. 6 (December 2005): 603–21. http://dx.doi.org/10.1260/136943305776318365.
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The effects of torsional coupling, due to isolator parameters, on the seismic response of base-isolated buildings are presented. The isolated building is modelled as a single-storey structure mounted on different isolation devices such as elastomeric and sliding systems involving non-linear restoring forces. The governing equations of motion for the uncoupled and torsionally coupled system are derived and solved in time domain by Newmark's method of integration to obtain lateral-torsional displacement response. The displacement response of the isolated system with different combinations of structural configurations, isolation systems and the ratio of uncoupled torsional to lateral frequency of the system is investigated. A comparison of the response of the torsionally coupled base-isolated building is made with the corresponding response obtained from torsionally uncoupled base-isolated building. In addition, a parametric study is conducted to observe the effect of superstructure flexibility on the displacements in torsionally coupled base-isolated building. The eccentricities arising due to the asymmetries in the isolation stiffness and/or yield strength of the isolators are compared with the eccentricity in the system as specified by the Uniform Building Code (UBC 1997). It is observed that the torsional coupling arising due to the dissimilarity in the isolator properties considerably influences the seismic response of the base-isolated building. Effects of superstructure eccentricity are found diminishing when the isolation eccentricities exist. The design bearing displacement suggested by the UBC static formula incorporating accidental torsion is found conservative for the isolation eccentricities arising due to the dissimilarity amongst the isolators.
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Qin, Li, and Chao Zhang. "Calculating Algorithm for Torsional Stiffness of Conductors-Spacers." Applied Mechanics and Materials 459 (October 2013): 669–73. http://dx.doi.org/10.4028/www.scientific.net/amm.459.669.
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In galloping of transmission lines, the twist of bundled conductors plays an important role. So the research of torsional stiffness of conductors-spacers for in-depth study of the galloping of the transmission lines is important.In addition to considering the impact of previous studies involving some of the torsional stiffness of bundled conductors factors (such as the torsional stiffness of sub conductor, the actual tension, etc.), but also the effects of sag and line height difference are considered. Finally a theoretical torsional stiffness of conductors-spacers formula is deduced. With the previous formula and the measured data on the different conductor types, different sub conductor spacing and different initial tension conditions, theresults of this formula are closer to the measured data.
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Farley, Claire T., Han H. P. Houdijk, Ciska Van Strien, and Micky Louie. "Mechanism of leg stiffness adjustment for hopping on surfaces of different stiffnesses." Journal of Applied Physiology 85, no. 3 (September 1, 1998): 1044–55. http://dx.doi.org/10.1152/jappl.1998.85.3.1044.
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When humans hop in place or run forward, leg stiffness is increased to offset reductions in surface stiffness, allowing the global kinematics and mechanics to remain the same on all surfaces. The purpose of the present study was to determine the mechanism for adjusting leg stiffness. Seven subjects hopped in place on surfaces of different stiffnesses (23–35,000 kN/m) while force platform, kinematic, and electromyographic data were collected. Leg stiffness approximately doubled between the most stiff surface and the least stiff surface. Over the same range of surfaces, ankle torsional stiffness increased 1.75-fold, and the knee became more extended at the time of touchdown (2.81 vs. 2.65 rad). We used a computer simulation to examine the sensitivity of leg stiffness to the observed changes in ankle stiffness and touchdown knee angle. Our model consisted of four segments (foot, shank, thigh, head-arms-trunk) interconnected by three torsional springs (ankle, knee, hip). In the model, an increase in ankle stiffness 1.75-fold caused leg stiffness to increase 1.7-fold. A change in touchdown knee angle as observed in the subjects caused leg stiffness to increase 1.3-fold. Thus both joint stiffness and limb geometry adjustments are important in adjusting leg stiffness to allow similar hopping on different surfaces.
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He, Liupeng, Changgao Xia, Sida Chen, Jiwei Guo, and Yi Liu. "Parametric Investigation of Dual-Mass Flywheel Based on Driveline Start-Up Torsional Vibration Control." Shock and Vibration 2019 (January 31, 2019): 1–12. http://dx.doi.org/10.1155/2019/3171698.
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This paper is aimed to investigate the influence of dual-mass flywheel (DMF) kinetic parameters on driveline torsional vibration in engine start-up process, which prescribes the design requirements under start-up condition for DMF matching. On the basis of driveline excitation analysis during engine start-up, the analytical model of DMF driveline torsional vibration system is built and simulated. The vehicle start-up test is conducted and compared with the simulation results. On account of the partial nonstationary characteristic of driveline during start-up, the start-up process is separated into 3 phases for discussing the influence of DMF rotary inertia ratio, hysteresis torque, and nonlinear torsional stiffness on attenuation effect. The test and simulation results show that the DMF undergoes severe oscillation when driveline passes through resonance zone, and the research model is verified to be valid. The DMF design requirements under start-up condition are obtained: the appropriate rotary inertia ratio (the 1st flywheel rotary inertia-to-the 2nd flywheel rotary inertia ratio) is 0.7∼1.1; the interval of DMF small torsion angle should be designed as being with small damping, while large damping is demanded in the interval of large torsion angle; DMF should be equipped with low torsional stiffness when working in start-up process.