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Journal articles on the topic 'Torsion'
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1
Lythe, G. R., and D. Surry. "Wind-induced torsional loads on buildings." Canadian Journal of Civil Engineering 19, no. 4 (August 1, 1992): 711–23. http://dx.doi.org/10.1139/l92-079.
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This paper examines the mean and peak torsional wind loads on tall buildings using two data bases of torsion measured experimentally in wind tunnel tests: the first, a large data base of mean torsional loads; and the second, a smaller data base of peak torsions. Although the mean load constitutes only a part of the total peak load required for design, it provides considerable insight into the aerodynamics of torsion, while improvement in its estimation also improves the estimation of the total peak load, using empirical gust factor methods. Comparisons between experimental results and the corresponding provisions of the 1985 National Building Code of Canada and Commentary indicate that, while the NBCC is a good estimator of mean shear loads, it significantly underestimates the mean torsional loads on tall buildings. The experimental data are further analysed to provide an improved estimation method for both the mean and the peak torsion. For mean torsion, this involves evaluating various definitions of the torsion coefficient and classifying building shapes in order to decrease the variability of the associated coefficients. This process leads to some notion of those shapes susceptible to large torsional loads and the most important building parameters on which to base predictions. This insight, along with the data base of peak torsion, is used to simplify and improve an existing method for estimating peak torsion, which was developed using a smaller data base. Key words: torsion, wind loading, codes, wind tunnel tests, tall buildings.
2
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.
3
Li, Xin, and Li Liang. "Experimental and Numerical Study on Torsional Behavior of Precast Concrete Screw Pile Body." Applied Mechanics and Materials 188 (June 2012): 137–43. http://dx.doi.org/10.4028/www.scientific.net/amm.188.137.
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Precast concrete screw pile is a new kind of pile foundation. Because the pile bears very large torsion in construction, the torsional properties of pile body including cracking torsion, ultimate torsion and torsional deformation were studied in this paper in order to improve the anti-torsional ability of precast concrete screw pile. Experimental method and numerical method are used to research the torsional behavior of precast concrete pile body. Experimental and numerical results of cracking torsion, ultimate torsion and relationship between torsion and angle of twist per unit length of different specimens are obtained. In addition, five factors of strength level of concrete, degree of prestress, distance of spiral hoop, concrete cover and diameter of spiral hoop influencing on torsional behavior of precast concrete pile body are researched by orthogonal numerical test. The rational finite element model and solution method are concluded for calculating the torsional behavior of concrete pile. Moreover, the rational pile type and design parameters of precast concrete screw pile are obtained.
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Nguyen, Thai Son, Ted Stathopoulos, and Lucia Tirca. "Wind-induced shear and torsion in low-rise and medium-rise buildings: Provisions of National Building Code of Canada 2015." Canadian Journal of Civil Engineering 45, no. 5 (May 2018): 339–50. http://dx.doi.org/10.1139/cjce-2017-0107.
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This paper discusses the shear and torsion induced in low-rise and medium-rise buildings, according to wind load specifications provided in NBCC 2015. Results from experimental studies, carried out in wind tunnels were compared with corresponding NBCC 2015 provisions under different upstream roughness conditions. These comparisons demonstrated notable discrepancies for the case of torsion in low-rise buildings. Further, comparisons between the wind load specifications given in NBCC 2015 and ASCE/SEI 7-10 standard were carried out. Following both sets of provisions, wind-induced shear and torsion were computed and compared for five low-rise and medium-rise buildings with the same horizontal dimensions but different heights. Emphasis was directed towards the cases that create maximum shear forces and (or) maximum torsions to reflect critical design conditions. For low-rise buildings, the ASCE/SEI-7-10 and NBCC-2015 yield similar shear coefficients but quite different torsional coefficients; while for medium-rise buildings, clear agreement was found, for both shear and torsion. The diversity of the results is discussed and some suggestions for improvement of code provisions are made. A definition for medium-rise buildings was provided.
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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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Shen, Kongjian, Shui Wan, YL Mo, and Xiayuan Li. "A softened membrane model for prestressed concrete composite box girders with corrugated steel webs under pure torsion." Advances in Structural Engineering 22, no. 2 (August 3, 2018): 384–401. http://dx.doi.org/10.1177/1369433218788597.
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Torsion can be regarded as a principal factor in some cases, such as in curved girders and eccentrically loaded girders, when conducting the structural analysis of prestressed concrete composite box girders with corrugated steel webs. Recently, a rational model, called the softened membrane model for torsion, was proposed for the torsional analysis of reinforced concrete members; thereafter, this model was extended to prestressed concrete members under pure torsion and called softened membrane model for torsion prestressed concrete. This article presents a modified model, the softened membrane model for torsion prestressed concrete for prestressed concrete composite box girders with corrugated steel webs, to analyze full torsional behavior. To build the model, the softened membrane model for torsion in reinforced concrete members is first extended to perform the torsional analysis of prestressed concrete composite box girders with corrugated steel webs by incorporating the torsional contribution of corrugated steel webs. Afterward, the initial stresses and strains due to prestressing are considered to extend the softened membrane model for torsion to softened membrane model for torsion prestressed concrete for prestressed concrete composite box girders with corrugated steel webs by modifying the equilibrium equations, convergence criteria, and constitutive laws of materials. The modified model is validated by experimental data and is proven to be capable of predicting the overall torque–twist curve, especially the precracked branch and postcracked ascending branch. In addition, a comparison between the softened membrane model for torsion and softened membrane model for torsion prestressed concrete indicates that the torque values before and after concrete cracking will be overestimated and underestimated, respectively, without considering the effect of the initial stresses and strains. Finally, another comparison shows that the softened membrane model for torsion prestressed concrete is superior to the rotating-angle truss model for torsion in its ability to predict the precracked branch of the torque–twist curve.
7
Gao, Hua Bin, and Yong Sheng Zhang. "Determination of Torsional Mode and Analysis of Torsional Resistance." Applied Mechanics and Materials 204-208 (October 2012): 1242–46. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.1242.
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At present, structural designers have many different views on determination of torsional mode. This paper adopts the structural mode factor and the mass participation factor method to determine structure torsional mode. Use the shear correction to simplify the calculation of structure torsion, derivate the relevant formulas of torsional effect, it has guide significance for manual calculation of structural torsion; Analysis of structural torsion resistant measures finally.
8
Qi, Zhiqiang, Cheng Zhang, Liang Qiao, Jian Qin, and Shunling Wang. "The Test Study on Tension-torsion Coupling Effect of ACSR in Overhead Transmission Lines." Journal of Physics: Conference Series 2731, no. 1 (March 1, 2024): 012027. http://dx.doi.org/10.1088/1742-6596/2731/1/012027.
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Abstract In order to analyze the relationship between the tensile and torsional characteristics of the Aluminum Conductor Steel Reinforced (ACSR), test research on the coupling effect of tension and torsion in conductors was carried out. A conductor tension-torsion coupling test device was designed, and selected the JL/G1A-630/45-45/7 ACSR as sample which is commonly used in ultra-high voltage AC engineering. The relationship between conductor tension, torque, and tensile strain, torsional strain was measured. And obtain the stiffness coefficients of conductor tension, torsion, and tension-torsion coupling. The testing results show that the tension and torque of the conductor gradually change from non-linear to linear under the action of tension or torsion deformation; The torsional stiffness Kφφ and tension-torsion coupling stiffness Kεφ when the conductor is turned to the right are greater than the corresponding stiffness when it is turned to the left.
9
Humar, J. L., and P. Kumar. "Torsional motion of buildings during earthquakes. II. Inelastic response." Canadian Journal of Civil Engineering 25, no. 5 (October 1, 1998): 917–34. http://dx.doi.org/10.1139/l98-032.
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In a previous study on the elastic torsional response of building models subjected to earthquake motion, it was shown that the current provisions of the National Building Code of Canada for design against torsion induced by earthquakes are quite conservative for the flexible edge of the building, but may be inadequate for the stiff edge. Based on the results of studies on the elastic response, a new set of design provisions was suggested. The present study deals with the inelastic torsional response of single- and multi-storey buildings designed according to the suggested provisions. Effects of both the natural and the accidental torsion are considered. It is shown that, given the complexity of inelastic response, particularly that of multistorey buildings, the suggested provisions can reasonably be used for the torsion design of single-storey buildings, as well as of multistorey buildings that are asymmetric in plan, but otherwise fairly regular.Key words: earthquake response, natural torsion, accidental torsion, inelastic torsional response, design for torsion.
10
Jeong, Byeong-Woo. "Transitional Failure of Carbon Nanotube Systems under a Combination of Tension and Torsion." Journal of Nanomaterials 2012 (2012): 1–6. http://dx.doi.org/10.1155/2012/847307.
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Transitional failure envelopes of single- and double-walled carbon nanotubes under combined tension-torsion are predicted using classical molecular dynamics simulations. The observations reveal that while the tensile failure load decreases with combined torsion, the torsional buckling moment increases with combined tension. As a result, the failure envelopes under combined tension-torsion are definitely different from those under pure tension or torsion. In such combined loading, there is a multitude of failure modes (tensile failure and torsional buckling), and the failure consequently exhibits the feature of transitional failure envelopes. In addition, the safe region of double-walled carbon nanotubes is significantly larger than that of single-walled carbon nanotubes due to the differences in the onset of torsional buckling.
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Peirone, B., D. Fox, and L. A. Piras. "Effects of antebrachial torsion on the measurement of angulation in the frontal plane: A cadaveric radiographic analysis." Veterinary and Comparative Orthopaedics and Traumatology 25, no. 02 (2012): 89–94. http://dx.doi.org/10.3415/vcot-10-09-0135.
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SummaryObjectives: To quantify the effect of antebrachial torsion on the miscalculation of radial valgus measured radiographically and to assess a radiographic positioning method used to mitigate torsion-associated artifactual miscalculation of concurrent frontal plane angulation.Methods: A canine cadaveric forelimb was used to model different combinations of valgus and external torsion. Valgus was induced in the limb in increments of five degrees, radiographic images were taken at each increment, and the observed radiographic valgus was measured. Various angles of torsion were then induced and the process was repeated for a range of torsional angles at 15° increments. For the second objective, the study was repeated with the forelimb rotationally re-positioned to mirror the degree of the induced torsion of the deformity at each valgus and torsion iteration.Results: Both zero degrees and 15° torsional iterations possessed mean artifactual valgus (AV) values between zero and five degrees for every valgus increment. With torsion of 30° and higher, mean AV values varied widely and did not fall within the zero to five degree accepted range. Rotationally re-positioning the limb in an attempt to alleviate the AV discrepancies resulted in the 30° torsional group having acceptable AV values for valgus values between zero and 20°.Clinical significance: Increasing antebrachial torsion interferes with accurate radiographic measurement of frontal plane deformities. Radiographically repositioning the limb allows the accurate calculation of more valgus and torsion combinations, but still results in miscalculations of more complex deformities.
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Hou, Pengliang, Huantao Jing, Yujie He, Hongwei Zhao, Haining Xiao, and Chunwei Zhang. "Study on the effects of the tension and torsion loading sequence on the mechanical properties of a 20 carbon steel." Materials Testing 64, no. 6 (June 1, 2022): 787–99. http://dx.doi.org/10.1515/mt-2021-2202.
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Abstract In engineering applications, cylindrical bars of 20 carbon steel are often subjected to a combination of tensile loading and torsional loading during the service, thereby causing premature failure or an accident. In order to explore the influence of loading sequence of tension and torsion on the mechanical properties of 20 carbon steel, tests of combined tension-torsion loading and combined torsion-tension loading are employed in this work. During experiments, a microscope is used for the in situ characterization of micro-damage evolution on the surface of specimens. At the same time, to analyze the influence of loading sequence on the stress distribution, ABAQUS software is utilized to conduct the relevant finite element simulation, where the results of finite element analysis are consistent with the experiments. Evidently, the torsional strength of 20 carbon steel is decreased with an increase in the pre-tensile stress, under the combined tension-torsion. However, the tensile strength of 20 carbon steel is enhanced with the increasing pre-torsional angles, under the combined torsion-tension. Moreover, the in situ images characterized the micro-damage evolution of 20 carbon steel under pure tension, pure torsion, combined tension-torsion and combined torsion-tension. It is concluded that the deference in loading sequence changes the failure mechanism of 20 carbon steel is different.
13
Zhu, Yingbo, Shui Wan, Kongjian Shen, Qiang Su, and Xiayuan Li. "Modified rotating-angle softened truss model for composite box-girder with corrugated steel webs under pure torsion." Advances in Structural Engineering 23, no. 9 (February 6, 2020): 1902–21. http://dx.doi.org/10.1177/1369433219898063.
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Replacement of traditional concrete webs with corrugated steel webs will lead to a significant decrease in torsional stiffness of composite box-girder with corrugated steel webs, which needs special attention in the design of wide and curved composite box-girder with corrugated steel webs. To improve the accuracy of prediction on the entire torsional performance of composite box-girder with corrugated steel webs, a modified rotating-angle softened truss model for torsion is developed in this study. Modified rotating-angle softened truss model for torsion mainly takes into account the new three-stage average stress coefficients, the new two-stage shear strain relationship between corrugated steel web and slabs, and the torsional deformation coordination of whole cross section. To testify the accuracy of modified rotating-angle softened truss model for torsion and to better understand the performance of composite box-girder with corrugated steel webs under pure torsion, two scaled specimens are tested in this article. The torque–twist curves and shear strains calculated by modified rotating-angle softened truss model for torsion reach a good agreement with experimental results, which indicates that modified rotating-angle softened truss model for torsion can successfully predict the entire torsional performance of composite box-girder with corrugated steel webs. In addition, compared with test data obtained from previous literature, the proposed modified rotating-angle softened truss model for torsion is more capable of predicting full torsional response of composite box-girder with corrugated steel webs than other rotating-angle models, especially at cracking stage and ultimate stage.
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Eroglu, Egemen, and Gokhan Gundogdu. "Isolated penile torsion in newborns." Canadian Urological Association Journal 9, no. 11-12 (November 4, 2015): 805. http://dx.doi.org/10.5489/cuaj.2833.
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Introduction: We reported on the incidence of isolated penile torsion among our healthy children and our approach to this anomaly.Methods: Between 2011 and 2014, newborn babies with penile torsion were classified according to the angle of torsion. Surgical correction (penile degloving and reattachment for moderate cases and dorsal dartos flap technique in case of resistance) after 6 months was advised to the babies with rotations more than 45°.Results: Among 1000 newborn babies, 200 isolated penile torsions were found, and among these, 43 had torsions more than 45°, and 4 of these had angles greater than 90°. The mean angle of the rotations was found 30.45° (median: 20°). In total, 8 children with 60° torsions were previously circumcised. Surgery was performed on 19 patients, with a mean patient age of 12 ± 2 months. Of these 19, 13 babies were corrected with degloving and reattachment. This technique was not enough on the remaining 6 patients; therefore, derotational dorsal dartos flap was added to correct the torsion. After a mean of 15.6 ± 9.8 months, residual penile rotation, less than 15°, was found only in 2 children.Conclusion: The incidence of isolated penile torsion is 20% in newborns. However, rotation more than 45° angles are seen in 4.3% of male babies. Correction is not necessary in mild degrees, and penile degloving with reattachment is enough in most cases. If the initial correction is insufficient, dorsal dartos flap rotation is easy and effective. Prior circumcision neither disturbs the operative procedure nor affects the outcomes.
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Močilnik, Vinko, Jožef Predan, and Nenad Gubeljak. "Effect of Residual Stresses on Fatigue Strength on the Smooth and Splined Parts of Spring Torsion Bars." Metals 13, no. 6 (May 23, 2023): 1004. http://dx.doi.org/10.3390/met13061004.
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The article discusses the effect of residual stresses on the fatigue strength of torsion bars by using the Dang Van fatigue criterion, at the stress concentration at the root of the tooth and at the smooth part of the torsion bar. Residual compressive stresses were induced on the surface during the technological processes by cold surface rolling and torsional pre-strain (pre-setting) to the plastic range, to increase the elastic linear range and to reduce the stress state during torsional loading. Normally, the stress reduction in the torsion bar at the mounting point is provided by the increased diameter of the splined part, compared to the smooth part of the torsion bar. In the case of a small difference between the diameter of the splined and the smooth parts of the torsion bar, a fatigue crack can be initiated in the notch, which causes the torsion bar to break during operation after a few hundred loading cycles. FEM stress analysis of a torsion bar was performed in the article. The actual residual stresses were measured by the non-destructive X-ray method at the place of stress concentration on the smooth and splined parts with a notch of the torsion bar, and Dang Van’s failure criterion was used to determine the fatigue behavior during torsional loading. Therefore, in the paper, the three methods were combined to determine the optimum lifetime of a torsion bar exposed to the required cyclic torque. The results of the analysis showed that the residual compressive stresses are useful up to a certain limit where the retarded fatigue crack initiation occurred, but a further increase of compressive stress caused an increase of the maximum shear stresses, which, in turn, caused the initiation of fatigue and failure at the splined part of the torsion bar before achieving the required number of cycles.
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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, Nan, Sébastien Mavromatis, Jean Sequeira, and Stéphane Curcio. "A Robust Method of Eye Torsion Measurement for Medical Applications." Information 11, no. 9 (August 21, 2020): 408. http://dx.doi.org/10.3390/info11090408.
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The detection of eye torsion is an important element for diagnosis of balance disorders, although it is rarely available in existing eye tracking systems. A novel method is proposed in this paper to provide robust measurement of torsional eye movements. A numerical approach is presented to estimate the iris boundary only according to the gaze direction, so the segmentation of the iris is more robust against occlusions and ambiguities. The perspective distortion of the iris pattern at eccentric eye positions is also corrected, benefiting from the transformation relation that is established for the iris estimation. The angle of the eye torsion is next measured on the unrolled iris patterns via a TM (Template Matching) technique. The principle of the proposed method is validated and its robustness in practice is assessed. A very low mean FPR (False Positive Rate) is reported (i.e., 3.3%) in a gaze test when testing on five participants with very different eye morphologies. The present method always gave correct measurement on the iris patterns with simulated eye torsions and rarely provided mistaken detections in the absence of eye torsion in practical conditions. Therefore, it shows a good potential to be further applied in medical applications.
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Cebra, Christopher K., Margaret L. Cebra, Franklyn B. Garry, and LaRue W. Johnson. "Surgical and nonsurgical correction of uterine torsion in New World camelids: 20 cases (1990–1996)." Journal of the American Veterinary Medical Association 211, no. 5 (September 1, 1997): 600–602. http://dx.doi.org/10.2460/javma.1997.211.05.600.
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Objective To report clinical findings for New World camelids with uterine torsion and to compare results of 3 methods of correction. Design Retrospective case series. Animals 11 llamas and 3 alpacas with 20 uterine torsions. Procedure Information concerning history, clinical signs, management, and postpartum complications was retrieved from medical records. Information concerning subsequent reproductive performance was obtained by telephone interview of owners. Results Uterine torsion was corrected by celiotomy (n = 7), transvaginal manipulation (5), or rolling the dam (8). Direction of 19 of 20 torsions was clockwise when viewed from the rear. Retention of fetal membranes was reported for 5 camelids that underwent celiotomy, but was not reported in camelids after nonsurgical correction. The uterus prolapsed in 1 llama that underwent celiotomy and in another that underwent the rolling technique. Although 2 camelids that underwent celiotomy subsequently failed to conceive, all camelids treated by nonsurgical techniques conceived. Clinical Implications Uterine torsion in camelids may be diagnosed by methods similar to those used in cattle. Surgical and nonsurgical methods can be used to correct torsion, and postpartum complications are rare when torsion is corrected by a nonsurgical method. (J Am Vet Med Assoc 1997;211:600–602)
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Elsharawy, Mohamed, Khaled Galal, and Ted Stathopoulos. "Comparison of wind tunnel measurements with NBCC 2010 wind-induced torsion provisions for low- and medium-rise buildings." Canadian Journal of Civil Engineering 41, no. 5 (May 2014): 409–20. http://dx.doi.org/10.1139/cjce-2013-0239.
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The aim of this study is to assess wind-induced torsional loads on low- and medium-rise buildings determined in accordance with the National Building Code of Canada (NBCC 2010). Two building models with the same horizontal dimensions but different gabled-roof angles (0° and 45°) were tested at different full-scale equivalent eave heights (6, 12, 20, 30, 40, 50, and 60 m) in open terrain exposure for several wind directions (every 15°). Wind-induced measured pressures were numerically integrated over all building surfaces and results were obtained for along-wind force, across-wind force, and torsional moment. Torsion load case (i.e., maximum torsion and corresponding shear) and shear load case (i.e., maximum shear and corresponding torsion) were evaluated to reflect the maximum actual wind load effects in the two horizontal directions (i.e., transverse and longitudinal). The evaluated torsion and shear load cases were also compared with the current torsion- and shear-related provisions in the NBCC 2010. The results demonstrated significant discrepancies between NBCC 2010 and the wind tunnel measurements regarding the evaluation of torsional wind loads on low- and medium-rise buildings. Finally, shear and torsion load cases were suggested for evaluating wind loads in the design of low- and medium-rise rectangular buildings.
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Lau, Ming G. "Torsional axisymmetric finite element model for problems in elasticity." Canadian Journal of Civil Engineering 13, no. 5 (October 1, 1986): 583–87. http://dx.doi.org/10.1139/l86-085.
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This note describes how the displacements and shear stresses of an axisymmetric elastic component, when loaded in torsion, can be computed by modelling the component with torsional axisymmetric finite elements. The model developed represents only minor modifications of the well-known plane stress or plane strain finite element technique.In the analysis, the model is split into a mesh of triangular annuli. Each node of each element has only one degree of freedom, the tangential displacement. The state of strain in each element is represented by a three-term displacement function, one representing a rigid body rotation, the second representing the state of torsion, and the third representing the state of strain in a hollow thin disc.The model has been applied satisfactorily to three torsional problems with known theoretical solutions. The first problem involves the computation of torsional shear stresses of a uniform shaft subjected to pure torsion. In the second problem, the solution is obtained for a conical shaft. In the third problem, known as the Reissner–Sagoci problem, an elastic semi-infinite medium is subjected to a torsional displacement on a small area of the surface.A typical application of the model to the problem of a shrink-fitted assembly subjected to torsion is discussed. Key words: torsion, finite element, elasticity, axisymmetry.
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Mohammed khalifah, Zahraa, and Mohammed Mohammed Rasheed. "THE EFFECT OF SIFCON ON TORSIONAL BEHAVIOR OF REINFORCED CONCRETE BEAMS." Journal of Engineering and Sustainable Development 26, no. 4 (July 1, 2022): 52–62. http://dx.doi.org/10.31272/jeasd.26.4.6.
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In recent years, research into the effects of torsion in concrete members and the impact of novel materials on torsional behavior has increased. Slurry Infiltrated Fiber Concrete (SIFCON) is a special kind of Fiber Reinforced Concrete (FRC). The purpose of this research is to study the influence of SIFCON on the torsion behavior of reinforced concrete beams. In the experimental program, five beam specimens are cast and tested under pure torsion. Two of them were from normal concrete as a reference, two from SIFCON with a steel fiber volume of 10% and the last beam was normal concrete strengthening by SIFCON with a steel fiber volume of 10%. The results have indicated enhancement in an ultimate torsional moment of SIFCON beams when compared with the reference, normal concrete beam. In addition, by reducing the twist angle and increasing torsional stiffness, the resistance moment of torsion was improved.
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Humar, J. L., and P. Kumar. "Torsional motion of buildings during earthquakes. I. Elastic response." Canadian Journal of Civil Engineering 25, no. 5 (October 1, 1998): 898–916. http://dx.doi.org/10.1139/l98-031.
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Analytical studies are carried out on the elastic torsional response of single- and multi-storey building models subjected to earthquake motion. Effects of both the natural and accidental torsion are considered. The results of analysis are compared with the design provisions of the National Building Code of Canada (NBCC). It is shown that the NBCC provisions for the design of resisting elements on the flexible side are overly conservative. On the other hand, provisions for the design of elements on the stiff side are conservative in some situations and inadequate in others. Modifications to the design provisions are suggested which give design forces closer to the results obtained from a dynamic analysis, and are at the same time simpler than the existing provisions. It is shown that the ratio of the uncoupled torsional and translational frequencies is an important parameter governing the torsional response and it would be a good practice in design to achieve a value greater than 1 for this ratio.Key words: earthquake response, natural torsion, accidental torsion, elastic torsional response, design for torsion.
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Li, Chun Bao, and Qing Wang. "Study on a New Linear Arrangement of Prestressed Concrete Beam." Applied Mechanics and Materials 94-96 (September 2011): 1471–75. http://dx.doi.org/10.4028/www.scientific.net/amm.94-96.1471.
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A new kind of prestressed concrete beams with spiral broken line cables subjected to torsions is present based on the fundamental principle of equivalent loads of prestressed reinforcement. It carried out the emulation analyses and load tests of the beams on spiral broken line cables and the general prestressed concrete beams with longitudinal cables. The results showed that the spiral broken line cables effectively postpone the cracking of the beam and increased both crack torsional moment and ultimate torsion moment, and kept some ductility.
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Tobushi, Hisaaki, Elzbieta Pieczyska, Kouji Miyamoto, and Kento Mitsui. "Shape-Memory Alloy Thin Strip Rotary Actuator." Materials Science Forum 674 (February 2011): 219–24. http://dx.doi.org/10.4028/www.scientific.net/msf.674.219.
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The torsional deformation properties of a TiNi shape-memory alloy thin strip were investigated. The results are summarized as follows. (1) The martensitic transformation starts at the edge of the thin strip. (2) The fatigue life in pulsating torsion is longer than that in alternating torsion. (3) A simple rotary driving element can be developed by using SMA-thin strip torsion.
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J. De-la-Colina and J. Valdés. "Eccentric force excitation of a reinforced concrete building to assess torsion amplification." Electronic Journal of Structural Engineering 11 (January 1, 2011): 1–10. http://dx.doi.org/10.56748/ejse.11138.
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Dynamic analysis should be preferred for seismic design of buildings and other structures instead of a static one. However, in several current building codes seismic static design of buildings requires an amplification of torsion moments (or story eccentricities) computed from lateral forces statically applied at floor levels. Discrepancy of factors used to estimate torsion amplification among codes suggests further study on this subject. The main objective of this paper is to show estimations of the building dynamic torsion. These estimations were obtained from experiments conducted in a four-story reinforced concrete building without accidental eccentricity that was excited with a dynamic force generator placed at the roof. The exciter was operated at several frequencies and it was placed at two roof positions. By assuming three degrees of freedom for each building slab and using acceleration records from tests, equations of motion of the system were used to estimate dynamic story torsional moments. Results support the idea that building torsional response also depends on coupling between the excitation force frequency and the building modal frequencies associated with torsion (either pure torsion or translation coupled with torsion).
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Jian, Ranran, Zhonghe Shi, Haichao Liu, Weimin Yang, and Mohini Sain. "Enhancing Mixing and Thermal Management of Recycled Carbon Composite Systems by Torsion-Induced Phase-to-Phase Thermal and Molecular Mobility." Polymers 12, no. 4 (April 1, 2020): 771. http://dx.doi.org/10.3390/polym12040771.
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A novel torsion screw has been proposed to resolve the inadequate control of mass transfer and the thermal management of two component polymer blends and their carbon fiber composites. The novel torsional screw distinctly introduced radial flow in the torsion screw channel, which is a significant improvement over the flow pattern developed by the conventional screw. The heat transfer and mixing behavior of melt mixtures are enhanced by adapting screws with torsion elements compared with the traditional screw elements. Heat transfer efficacy in the polypropylene–polystyrene bi-phasic extrusion process improved with the increase in torsion element numbers. An increased number of newly designed torsional elements also improved the dispersion of minor phase in bi-phase polypropylene–polystyrene composition and their carbon fiber composites. The unique flow pattern induced by the torsion elements shows a synergistic effect on the melt-phase mass flow and the thermal flow field facilitating phase-to-phase thermal and molecular mobility and enhanced fiber orientation, crystallinity and mechanical properties of composite made from recycled carbon fiber/polypropylene. Microtomographs of recycled carbon fiber demonstrated the extraordinary ability of a torsion screw element to orient carbon fiber in both axial and radial directions.
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Almaraz, Gonzalo Mariano Domínguez, Luis Miguel Torres Duarte, and Christian Jesús Torres Pacheco. "Tension-Torsion Fatigue Tests on the proton Exchange membrane Nafion 115, used in fuel cells." South Florida Journal of Development 2, no. 5 (October 15, 2021): 6840–49. http://dx.doi.org/10.46932/sfjdv2n5-037.
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Fatigue tests under tension-torsion have been carried out on the membrane Nafion 115 (Perfluorosulfonic acid, PFSA). This polymeric material is a main component to construct fuel cells, used as proton exchange membrane. These membranes undergo mechanical loading of tension and torsion during its industrial life. A self-designed machine has been constructed to obtain the fatigue endurance on this polymeric material under tension-torsion and the following conditions: one magnitude for the torsion angle, five initial tensile stresses, room temperature, and environmental relative humidity, and frequency of 1.6 Hz. The experimental results show that fatigue endurance decreases with the increase of tensile stress when the torsion angle remains constant, as well as temperature and relative humidity (both taken at environmental conditions). Fracture surfaces were analyzed by SEM, in order to investigate the principal trends of crack initiation and propagation under this modality of fatigue loading.
Se han realizado ensayos de fatiga bajo tensión-torsión en la membrana Nafion 115 (ácido perfluorosulfónico, PFSA). Este material polimérico es un componente principal para la construcción de pilas de combustible, utilizado como membrana de intercambio de protones. Estas membranas se someten a cargas mecánicas de tensión y torsión durante su vida industrial. Se ha construido una máquina de diseño propio para obtener la resistencia a la fatiga de este material polimérico bajo tensión-torsión y en las siguientes condiciones: una magnitud para el ángulo de torsión, cinco tensiones iniciales de tracción, temperatura ambiente y humedad relativa ambiental, y frecuencia de 1,6 Hz. Los resultados experimentales muestran que la resistencia a la fatiga disminuye con el aumento de la tensión de tracción cuando el ángulo de torsión se mantiene constante, así como la temperatura y la humedad relativa (ambas tomadas en condiciones ambientales). Las superficies de fractura fueron analizadas por SEM, con el fin de investigar las principales tendencias de iniciación y propagación de grietas bajo esta modalidad de carga de fatiga.
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KREUZER, MAXIMILIAN, and HARALD SKARKE. "LANDAU-GINZBURG ORBIFOLDS WITH DISCRETE TORSION." Modern Physics Letters A 10, no. 13n14 (May 10, 1995): 1073–85. http://dx.doi.org/10.1142/s0217732395001198.
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We complete the classification of (2, 2) vacua that can be constructed from Landau-Ginzburg models by Abelian twists with arbitrary discrete torsions. Compared to the case without torsion, the number of new spectra is surprisingly small. In contrast to a popular expectation mirror symmetry does not seem to be related to discrete torsion (at least not in the present compactification framework). The Berglund-Hübsch construction naturally extends to orbifolds with torsion; for more general potentials, on the other hand, the new spectra neither have nor provide mirror partners in our class of models.
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Dowswell, Bo. "Torsion of Rectangular Connection Elements." Engineering Journal 56, no. 2 (June 30, 2019): 63–88. http://dx.doi.org/10.62913/engj.v56i2.1147.
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Traditionally, the torsional design of rectangular members has been based on elastic calculations. For member design, this approach is justified because beams subjected to torsion are usually controlled by torsional rotation serviceability limits. However, designs that are based on a first yield criterion underestimate the strength of connection elements. To evaluate the true torsional behavior of connection elements, various factors affecting the torsional strength of short rectangular members are investigated, showing that the torsional strength of connection elements can be predicted with rational analysis models using an ultimate strength approach. A method is proposed for calculating the strength of rectangular connection elements subjected to any possible combination of loads, including torsion. The design method results in a significant increase in torsional strength compared to traditional analysis methods. The method can be used to analyze extended single-plate connections subjected loads in any direction, including axial forces and combined vertical and horizontal shear forces. Three design examples show the proper application of the design method.
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Men, Jin Jie, Qing Xuan Shi, and Qiu Wei Wang. "Unity Equation of Torsional Capacity for RC Members Subjected to Axial Compression, Bend, Shear and Torque." Advanced Materials Research 163-167 (December 2010): 874–79. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.874.
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The mechanics performance of reinforced concrete members subjected to axial compression, bending, shear and torque is very complex. Several calculation models have been established to estimate the torsional capacity of combined torsion members; however, the calculation results of different models have a great variation. In this paper, variable-angle space truss model is adopted to analyze the mechanics performance of reinforced concrete members subjected to combined torsion. With respect to various shapes of specimens, various load modes, and various strength of concrete, a unity equation about torsional capacity of combined torsional member is obtained. Based on the unity equation, the torsional capacity of 59 combined torsional specimens is calculated. In contrast with the equation of ACI and the code of China, the torsional capacity calculated by the unity equation agrees well with the results of experiment and much better than the results of ACI code and China code. It is concluded that the unity equation can provide valuable reference for calculation and design of combined torsion members.
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Sun, Heng Hui, Ai Wu Zhao, Mao Feng Zhang, Da Li, Da Peng Wang, Li Kai Zhu, and Mei Tao. "The Analysis Model of Torsion Behavior for Octopus-Inspired Robotic Arm." Applied Mechanics and Materials 461 (November 2013): 917–23. http://dx.doi.org/10.4028/www.scientific.net/amm.461.917.
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Abstract. Octopus can achieve a variety of dexterous movements at any point along its arm, such as elongating, shorting, bending, twisting, or changing the stiffness, which have been considered as an interesting model of inspiration in robotics. Among the complex behaviors, the torsion behavior is important because it provide extra degree of freedom of movement, like twisting. This paper proposed a detailed dynamic model that describes the torsion behavior of octopus arm, based on torsional vibration theory. The initial conditions and boundary conditions that explained the main features of the torsion behaviors of octopus arm are acknowledged. The mode shapes, which describe the torsional vibration frequency and type, were solved as the sum of the time and the distance from the fixed end to where the deformation happened. By comparing the mode shapes results solved by the method proposed in this paper and by FEA Soft ANSYS, the effectiveness of this method has been verified. Further torsional stresses and torsion angles of deformation and vibrations on rod can be expressed as the functions of the mode shapes and the external torque exerted on one end of the rod. This method can be applied to calculate the kinematics results of the torsion behaviors and the appropriate activations related for continuum robotic manipulators inspired by octopus arm.
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Takeuchi, Mayumi, Kenji Matsuzaki, and Masafumi Harada. "Susceptibility-weighted MR sequence for the evaluation of ovarian masses with torsion." British Journal of Radiology 93, no. 1109 (May 1, 2020): 20200110. http://dx.doi.org/10.1259/bjr.20200110.
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Objective: Adnexal torsion is a rare gynecologic emergency caused by twisting of an adnexal mass. Twisted vascular pedicle is the most specific imaging finding for adnexal torsion, however, identification of twisted vascular pedicle can be challenging. The purpose of this study is to evaluate the feasibility of susceptibility-weighted MR sequence (SWS) for the diagnosis of adnexal torsion. Methods: MR imaging including SWS (SWAN: susceptibility-weighted angiography) of surgically proven four benign ovarian masses with torsion (one acute and three subacute to chronic torsions) were retrospectively evaluated. Three cystic masses and one solid mass were included in this study. Results: High signal intensity venous thrombus within the twisted vascular pedicle on T1-weighted imaging (T1WI) was detected in three lesions with subacute to chronic torsion (75%) but not in one lesion with acute torsion, whereas susceptibility-induced signal voids within the twisted vascular pedicle on SWAN were detected in all four lesions (100%). Conclusion: The demonstration of venous thrombus in the twisted vascular pedicle by SWS may be diagnostic for adnexal torsion. Advances in knowledge: SWS can detect blood products sensitively and can reveal venous thrombus in the twisted vascular pedicle, which may be helpful for the diagnosis of adnexal torsion.
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Dana, Bima Cahya Maula, Syamsul Hadi, Hangga Wicaksono, and Kris Witono. "THE EFFECT OF THE ANGLE AND DIMENSIONS OF A CROSS-SECTION SPECIMEN ON THE TORSIONAL STRENGTH OF AISI 1020 SQUARE STEEL SHAFT." LOGIC : Jurnal Rancang Bangun dan Teknologi 24, no. 1 (March 31, 2024): 9–16. http://dx.doi.org/10.31940/logic.v24i1.9-16.
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The unknown torsional strength due to the inconsistency of the angles and dimensions of the square cross-section of AISI 1020 steel specimens in the torsion test is the problem encountered. The research method included: preparation of square AISI 1020 steel specimens measuring 6 mm x 6 mm x 160 mm, measurement of 2 diagonal angles of the cross section of the specimen and dimensions of the cross section at 5 observation points along the specimen receiving torsion loads, torsion testing of specimens, analysis of torsion test results data, and drawing conclusions. The results of the study affect the angle and dimensions of the specimen cross-section on the torsional strength of the AISI 1020 steel square shaft which has a greater value at the angles of 89o and 91o than 90o which with an angle of 89o at dimensions of 5.96 mm x 5.96 mm has a torsional strength of 412 MPa, while at an angle of 90o with dimensions of 5.96 mm x 5.96 mm it has a torsional strength of 359 MPa, and for an angle of 91o in dimensions of 5.95 mm x 5.95 mm has a torsional strength of 402 MPa. The average torsional strength is achieved in the range of 351 to 397 MPa, at an angle of 89o the torsional strength increases by 46 MPa or around 13.1 %, and at an angle of 91o the torsional strength increases by 43 MPa or around 12.3%.
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Yu, Zhigang, and Deshan Shan. "Experimental and numerical studies of T-shaped reinforced concrete members subjected to combined compression-bending-shear-torsion." Advances in Structural Engineering 24, no. 12 (May 17, 2021): 2809–25. http://dx.doi.org/10.1177/13694332211012577.
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The study of reinforced concrete members subjected to combined loads always has been an important research topic in the field of engineering, but the torsional behavior of T-shaped reinforced concrete members subjected to combined loads has yet to be determined. This paper is focused on providing a detailed explanation of the torsional behavior of T-shaped reinforced concrete members subjected to combined compression-bending-shear-torsion. From the perspective of experimental tests and numerical analyses, in this paper, we discuss the effects of combined loads on the torsion bearing capacity, the development of cracks and the failure mode, strains of key points in the concrete and longitudinal reinforcement, and the relation of torsion and angular displacement. We conducted experiments and numerical analyses of four groups of reinforced concrete members by using the main variables of the axial pressure ratio and the bending moment. Also, the experimental and calculated results are compared based on the elastic-plastic damage constitutive model of concrete. Based on the test data and the existing formula, we also extended the formula used to calculate the torsion bearing capacity and provided diagrams of the interaction when combined loads were applied. In addition, the results of this study highlight the turning point from torsion failure to compression-bending-torsion failure. The test results demonstrated that torsion capability increases in the specified range of axial pressure ratio and decreases as bending increases. The test results also indicate the importance of considering the effects of compression-shear-bending on the torsion bearing capacity in the engineering design.
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Guerra, Waltraud Kleist-Welch, and Henry W. S. Schroeder. "Peripheral Nerve Palsy by Torsional Nerve Injury." Neurosurgery 68, no. 4 (April 1, 2011): 1018–24. http://dx.doi.org/10.1227/neu.0b013e31820a548c.
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Abstract BACKGROUND: Peripheral nerve palsy caused by torsional nerve injury is rare. Only a few patients have been reported in the literature. The etiology of this type of nerve lesion is poorly understood. OBJECTIVE: To report on 5 patients presenting with peripheral nerve palsy caused by a torsional nerve injury. METHODS: Five patients presented with 6 upper peripheral nerve palsy involving the axillary nerve (n = 2), musculocutaneous nerve (n = 2), radial nerve (n = 1), and suprascapular nerve (n = 1). There was no history of trauma in 3 patients, but in the other 2 patients, nerve palsy occurred after a traumatic event. Because of a lack of spontaneous recovery, surgical exploration was performed. Torsion of the whole nerve (n = 5) or only 1 fascicle (n = 1) was found. Epifascicular epineurectomy and detorsion, as well as resection of the torsion site with subsequent primary nerve suture, were performed in 3 lesions. RESULTS: Good to excellent recovery of motor function was achieved in all 5 patients. In the last patient who presented with 2 nerve torsions, the follow-up period after the last surgery is too short to allow evaluation. CONCLUSION: Although not a frequent event, torsional nerve injury should be taken into consideration when dealing with peripheral nerve injuries. Surgical exploration with detorsion or suture results in good recovery.
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Hasdemir, Pinar Solmaz, Fatma Eskicioglu, Gokhan Pekindil, Ali Riza Kandiloglu, and Tevfik Guvenal. "Adnexal Torsion with Dystrophic Calcifications in an Adolescent: A Chronic Entity?" Case Reports in Obstetrics and Gynecology 2013 (2013): 1–3. http://dx.doi.org/10.1155/2013/235459.
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Intermittent pelvic pain caused by ovarian cysts in adolescence may be due to torsion or partial torsion of the ovary. We present a case of 18-year old adolescent with symptomatic left ovarian torsion with calcifications demonstrated by pelvic MRI and ultrasonography prior to surgery. The pathologic investigation demonstrated dystrophic calcifications. We speculated that the pattern of the intermittent pain in the story of the patient and the dystrophic calcifications in pathologic investigation which is thought that it might have been potentially developed as a result of chronic hypoxia due to intermittent partial torsions over a period of two years.
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Martins, Renata de Castro, Maria Guiomar de Azevedo Bahia, and Vicente Tadeu Lopes Buono. "The Influence of Cyclic Straining in Torsion on Fatigue Resistance and Torsional Properties of ProTaper NiTi Endodontic Instruments." Materials Science Forum 643 (March 2010): 79–90. http://dx.doi.org/10.4028/www.scientific.net/msf.643.79.
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This study evaluated the influence of cyclic straining in torsion on fatigue resistance and torsional properties of ProTaper (S1, S2, F1, F2, F3) NiTi instruments. The mechanical behavior was evaluated by means of torsion and bending tests, performed according to ISO 3630-1 specification, while the fatigue resistance was evaluated using a bench test device employing an artificial canal with 5mm curvature radius and angle of curvature of 45º. The dimensional aspects, diameter (D3) and cross-sectional area (A3) at 3mm from the tip of the instruments were determined by means of image analysis of optical and scanning electron microscopy (SEM). The surface characteristics of instruments before and after they were submitted to cyclic straining in torsion and the morphological aspects of the fractured surfaces were analyzed by SEM. The maximum torque and the bending moment at 45º were higher for instruments with larger D3 and A3. The F1 and F2 instruments followed the Coffin-Manson’s relation, i.e., their number of cycles to failure (NCF) varied inversely with the strain amplitude. With the exception of S1 and S2 instruments, there was a tendency of decreasing the maximum torque after the instruments have been submitted to cyclic straining in torsion. With the exception of S1 instruments, there was a tendency of decreasing the NCF after torsional cycling. The analyses by SEM showed the presence of longitudinal cracks on the instruments previously cycled in torsion. The morphological aspects of the fractured surfaces of instruments tested in torsion or flexural fatigue did not changed by the cyclic straining in torsion. These changes in mechanical properties with torsional cycling can be related to the generation of imperfections such as longitudinal cracks on the instruments.
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Pateliya1, Chintan S., J. A. Patel, A. J. Dhami, S. B. Patel, and H. L. Makwana. "Incidence of Uterine Torsion and Related Factors in Buffaloes of Amul Milk Shed Area." INDIAN JOURNAL OF VETERINARY SCIENCES AND BIOTECHNOLOGY 15, no. 01 (June 1, 2019): 17–20. http://dx.doi.org/10.21887/ijvsbt.15.1.4.
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A study was carried out to find out the retrospective incidence of uterine torsion in buffaloes among obstetrical cases in Amul milk shed area and factors influencing it. Data on 1,13,772 obstetrical cases attended from January 2017 to June 2018 by Amul Veterinarians were collected. Moreover, 50 buffaloes suffering from uterine torsion were taken up during July-December, 2018 to know the side, site, degree of uterine torsion, parity as well as sex and viability of the calf and the dam after detorsion/Caesarean section in the same area. In the retrospective study, a total of 2000 cases of uterine torsion were recorded among total 1,13,772 bovine obstetrical cases, which encompassed 1.76%. Of the 2000 cases, 92.20 (1844) percent torsions were found in buffaloes only. Among 57,111 obstetrical cases attended in buffaloes, the incidence of uterine torsion was 3.23%. Moreover, the region/center-wise incidence of torsion cases varied from 1.30–19.36%. The highest incidence of uterine torsion was found in Anand region (19.36 %) followed by Kathlal (11.23 %) and Mahemdabad (10.14 %) regions, while the lowest incidence was in Virpur (2.06%), Petlad (1.46%) and Piplata (1.30%). It was concluded that buffaloes mostly experience right side (100%), post-cervical (82%) uterine torsion of 270–360° (66%), at full term of gestation (70%)with lower survivability of the calves (30%), however, the survival rate of the dams post-treatment was 90%.
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He, Haoxiang, Wentao Wang, and Honggang Xu. "Multidimensional Seismic Control by Tuned Mass Damper with Poles and Torsional Pendulums." Shock and Vibration 2017 (2017): 1–14. http://dx.doi.org/10.1155/2017/5834760.
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Due to the eccentric characteristics and the torsional excitation of multidimensional earthquakes, the dynamic response of asymmetry structure involves the translation-torsion coupling vibration and it is adverse to structural performance. Although the traditional tuned mass damper (TMD) is effective for decreasing the translational vibration when the structure is subjected to earthquake, its translation-torsion coupled damping capacity is still deficient. In order to simultaneously control the translational responses and the torsional angle of asymmetry structures, a new type of tuned mass damper with tuned mass blocks, orthogonal poles, and torsional pendulums (TMDPP) is proposed. The translation-torsion coupled vibration is tuned by the movement of the mass blocks and the torsional pendulums. According to the composition and the motion mechanism of the TMDPP, the dynamic equation for the total system considering eccentric torsion effect is established. The damping capacity of the TMDPP is verified by the time history analysis of an eccentric structure, and multidimensional earthquake excitations are considered. The damping effect of the traditional TMD and the TMDPP is compared, and the results show that the performance of TMDPP is superior to the traditional TMD. Moreover, the occasional amplitude amplification in TMD control does not appear in the TMDPP control. The main design parameters which affect the damping performance of TMDPP are analyzed.
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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, Yan Dong, and Yi Qiao Yang. "Torsion Textures Simulation by Considering Rigid Body Rotation." Materials Science Forum 654-656 (June 2010): 338–41. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.338.
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In this paper, the torsional texture evolution of pearlitic steel wire is simulated by Full Constrains (FC) Taylor model. The simulation results indicate that a simple shear deformation can not explain the experiments results of torsion texture. Bring in additional rigid body rotation and rational shear deformation can emersion the torsion texture very well. The different deformation styles are imposed to the FC Taylor, a group of parameters is given to explain the torsion texture evolution.
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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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Lin, Yao, Shan Liu, Tao Wu, and Guangchun Wang. "Effects of Unidirection/Bidirection Torsional Thermomechanical Processes on Grain Boundary Characteristics and Plasticity of Pure Nickel." Materials 15, no. 1 (December 29, 2021): 236. http://dx.doi.org/10.3390/ma15010236.
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The “torsion and annealing” grain boundary modification of pure nickel wires with different diameters was carried out in this paper. The effects of torsional cycles as well as unidirectional/bidirectional torsion methods on grain boundary characteristic distribution and plasticity were investigated. The fraction of special boundaries, grain boundary characteristic distributions and grain orientations of samples with different torsion parameters were detected by electron backscatter diffraction. Hardness measurement was conducted to characterize the plasticity. Then, the relationship between micro grain boundary characteristics and macro plasticity was explored. It was found that the special boundaries, especially Σ3 boundaries, are increased after torsion and annealing and effectively broke the random boundary network. The bidirectional torsion with small torsional circulation unit was the most conducive way to improve the fraction of special boundaries. The experiments also showed that there was a good linear correlation between the fraction of special boundaries and hardness. The plasticization mechanism was that plenty of grains with Σ3 boundaries, [001] orientations and small Taylor factor were generated in the thermomechanical processes. Meanwhile, the special boundaries broke the random boundary network. Therefore, the material was able to achieve greater plastic deformation. Moreover, the mechanism of torsion and annealing on the plasticity of pure nickel was illustrated, which provides theoretical guidance for the pre-plasticization of nickel workpieces.
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SETKIT, Monthian, Thanongsak IMJAI, Udomvit CHAISAKULKIET, Reyes GARCIA, Komsan DANGYEM, Katipoj SANUPONG, and Weerasit CHAMNANKIT. "Torsional Strengthening of Low-Strength RC Beams with Post-Tensioned Metal Straps: An Experimental Investigation." Walailak Journal of Science and Technology (WJST) 17, no. 12 (December 1, 2020): 1399–411. http://dx.doi.org/10.48048/wjst.2020.11908.
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This article investigates the behaviour of low-strength reinforced concrete beams under pure torsion with and without strengthening. Four beams were cast and tested in torsion: i) a control beam without vertical reinforcement, ii) two beams with internal stirrups designed for shear and torsion demands using different stirrup spacing (50 and 100 mm), and iii) a beam having steel stirrups with a spacing of 100 mm strengthened using high ductile post-tensioned metal straps (PTMS). The main objective of the PTMS strengthening solution was to investigate the enhancement of torsional strength confined along the beam. The failure modes, torsional capacities, rotation, and strengthening performance in torsion are discussed in in this study. The experimental results indicate that the PTMS improved the cracking torque capacity by up to 15 % compared to the control beam. Moreover, the PTMS also increased the ultimate torque by up to 19 % compared to the unstrengthened beam. Current code equations to predict the torsional capacity of RC beams are also compared with the experimental results. It is found that the predictions obtained by current ACI equation gives a good agreement and yield in general conservative values compared to the experimental ones.
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Basar, Nora Adliyanti, Dahril Dahril, Tita Menawati, and Fajriah Fajriah. "PENGARUH TORSIO TESTIS TERHADAP GANGGUAN PROSES SPERMATOGENESIS PADA TESTIS TIKUS (Rattus norvegicus)." Jurnal Kedokteran Syiah Kuala 17, no. 2 (August 1, 2017): 84–92. http://dx.doi.org/10.24815/jks.v17i2.8987.
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Abstrak. Torsio testis adalah terputarnya atau melilitnya korda spermatika, yang menyebabkan terputusnya aliran darah ke testis dan struktur jaringan di dalam skrotum. Penelitian yang bertujuan untuk mengidentifikasi efek variasi durasi waktu torsio testis terhadap proses spermatogenesis yang meliputi: jumlah sel Sertoli, spermatogonia, spermatosit primer, dan round spermatid testis Rattus norvegicus dilakukan dengan menggunakan rancangan acak lengkap (RAL) dan dibagi dalam 3 kelompok yaitu kontrol (KO) dan perlakuan (P1 dan P2). Kelompok perlakuan diinduksi torsio 360o pada testis kiri selama 4 dan 8 jam. Masing-masing kelompok terdiri dari 5 ekor tikus yang diamati langsung (efek cepat) dan 5 ekor tikus yang diamati setelah 30 hari dilakukan detorsi (efek lambat). Data dianalisa dengan metode ANOVA multifaktorial dan dilanjutkan dengan uji Tuckey HSD. Hasil penelitian menunjukkan bahwa rerata jumlah sel Sertoli pada KO: 142,00 ± 12,36; P1: 48,40 ± 8,00; P2: 35,70 ± 16,28, rerata jumlah spermatogonia KO: 975,30 ± 95,12; P1: 563,70 ± 170,44; P2: 321,10 ± 181,20, rerata jumlah spermatosit primer KO: 1307,50 ± 87,57; P1: 881,50 ± 253,65 ; P2: 505,80 ± 163,69, rerata round spermatid KO: 1237,20 ± 148,75; P1: 766,10 ± 277,68; P2: 473,00 ± 133,25. Berdasarkan hal tersebut, dapat disimpulkan bahwa torsio testis selama 4 dan 8 jam mengakibatkan perubahan jumlah sel Sertoli, spermatogonia, spermatosit primer, dan round spermatid (P0,05). Diharapkan, penanganan segera kasus torsio testis dapat menurunkan angka kerusakan testis. (JKS 2017; 2: 83-93)Kata kunci : torsio testis, proses spermatogenesis, jumlah sel SertoliAbstract. Testicular torsion is the spermatic cord twisted, which causes the interruption of blood flow to the testicles and structures within the scrotum. The research was subjected to identify the effect of various duration of testicular torsion to spermatogenesis process include on the amount of Sertoli cells, spermatogonia, primary spermatocytes, and spermatids round of Rattus norvegicus testes. This experimental research using completely randomized design (CRD) and contains of 3 groups: control (KO) and experimental groups (P1 and P2). The experimental groups which contains 20 rats underwent 360o unilateral left testicular torsion for 4 hours (P1) and 8 hours (P2). Five rats for each groups were examined after testicular torsion induced (short term effect) besides five other remained were examined after 30 days testicular tortion repaired (long term effect). Data were analyzed using ANOVA multifactorial followed by Tuckey’s HSD test. The result showed significant differences (P0,05). Between KO: 142.00 ± 12.36; P1: 48.40 ± 8.00; and P2: 35.70 ± 16.28 in the amount of Sertoli cells, between KO: 975.30 ± 95, 12: P1: 563.70 ± 170.44; P2: 321.10 ± 181.20 in the amount of spermatogonia, between KO: 1307.50 ± 87.57; P1: 881.50 ± 253.65; P2: 505, 80 ± 163.69 in the amount of primary spermatocytes, between KO: 1237.20 ± 148.75; P1: 766.10 ± 277.68; P2: 473.00 ± 133,25 in the amount of spermatids round. Therefore, testicular torsion for 4 and 8 hours resulted in changes in the amount of Sertoli cells, spermatogonia, primary spermatocytes, and spermatids round (P0,05). Expected, the immediate treatment of cases of testicular torsion may reduce the number of testicular damage. (JKS 2017; 2: 83-93)Keywords: testicular torsion, spermatogenesis process, the amount of Sertoli cell
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Mahmoud, Shereen, Ahmed Youssef, and Hamed Salem. "Enhanced Torsion Mechanism of Small-Scale Reinforced Concrete Beams with Spiral Transverse Reinforcement." Civil Engineering Journal 8, no. 11 (November 1, 2022): 2640–60. http://dx.doi.org/10.28991/cej-2022-08-11-019.
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The nonlinear torsional behaviour of small-scale reinforced concrete (RC) beams with continuous staggered spiral as transverse reinforcement stirrups is experimentally investigated. Twelve miniatures RC beams were tested under torsion load considering the closed shape of stirrups and compared with continuous staggered spiral ones. All miniatures beams were scaled down to be one-eighth the prototype beam size. The main parameters considered in this research are stirrup spacing and its configurations. Small scale RC beams were taken into account in the existing study because of their construction simplicity and financial feasibility. Mortar without coarse aggregate was applied instead of concrete to reduce the size effect of applying small scale models. Ongoing research trials have been carried out to obtain an efficacious approach to boost torsion failure mechanisms because brittle torsion failure of RC structural elements should be avoided. This study emphasized boosted torsion capacity, dissipated energy, and helical crack propagation. During testing, the primary cracking torsion moment, ultimate torsion moment, peak twist angle, and failure mechanism of the beams were inspected. The use of spiral stirrups showed great enhancement of the torsional behaviour of samples. It was observed that using spiral stirrups rather than closed stirrups could result in a substantial increase in torsion capacity and dissipated energy of 87.7% and 89.8%, respectively. As a result, the predicted capacities of the RC beams prototype were estimated in detail, taking account the scale down factor implemented by the authors. Values obtained based on international specifications and guidelines were used to compare the experimental results. Doi: 10.28991/CEJ-2022-08-11-019 Full Text: PDF
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Ecsedi, István, Ákos József Lengyel, Attila Baksa, and Dávid Gönczi. "Saint-Venant’s torsion of thin-walled nonhomogeneous open elliptical cross section." Multidiszciplináris tudományok 11, no. 5 (2021): 151–58. http://dx.doi.org/10.35925/j.multi.2021.5.15.
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This paper deals with the Saint-Venant’s torsion of thin-walled isotropic nonhomogeneous open elliptical cross section whose shear modulus depends on the one of the curvilinear coordinates which define the cross-sectional area of the beam. The approximate solution of torsion problem is obtained by variational method. The usual simplification assumptions are used to solve the uniform torsion problem of bars with thin-walled elliptical cross-sections. An example illustrates the application of the derived formulae of shearing stress and torsional rigidity.
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Buccino, Federica, Giada Martinoia, and Laura Maria Vergani. "Torsion—Resistant Structures: A Nature Addressed Solution." Materials 14, no. 18 (September 17, 2021): 5368. http://dx.doi.org/10.3390/ma14185368.
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The complexity of torsional load, its three-dimensional nature, its combination with other stresses, and its disruptive impact make torsional failure prevention an ambitious goal. However, even if the problem has been addressed for decades, a deep and organized treatment is still lacking in the actual research landscape. For this reason, this review aims at presenting a methodical approach to address torsional issues starting from a punctual problem definition. Accidents and breaks due to torsion, which often occur in different engineering fields such as mechanical, biomedical, and civil industry are considered and critically compared. More in depth, the limitations of common-designed torsion-resistant structures (i.e., high complexity and increased weight) are highlighted, and emerge as a crucial point for a deeper nature-driven analysis of novel solutions. In this context, an accurate screening of torsion-resistant bio-inspired unit cells is presented, taking inspiration specifically from plants, that are often subjected to the torsional effect of winds. As future insights, the actual state of technology suggests an innovative transposition to the industry: these unit cells could be prominently implied to develop novel metamaterials that could be able to address the torsional issue with a multi-scale and tailored arrangement.
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Trunin, Konstantin. "Mathematical Model of Flexible Link Dynamics in Marine Tethered Systems Considering Torsion and its Influence on Tension Force." Polish Maritime Research 30, no. 2 (June 1, 2023): 188–96. http://dx.doi.org/10.2478/pomr-2023-0032.
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Abstract The rigidity in bending of a flexible link (is an important characteristic that should be considered during regular service conditions. The tension and bending with torsion of wire ropes are also significant factors. This study proposed a method to calculate the vectors of the generalised forces of bending of flexible links. One of the causes of torsional stresses in the power plant of underwater tethered systems is the interaction with ship equipment, such as spiral winding on the winch drum, friction on the flanges of the pulleys or winch drums, and bends on various blocks and rolls that cause torsion. The source of torsional stresses in the FL may also be related to manufacturing, storage, transportation, and its placement on the ship’s winch drums. Torsion can lead to a decrease in the tensile strength due to load redistribution between power elements, or even a violation of their structure. In some cases, torsion significantly affects the movement of the underwater tethered system as a whole. The development of a mathematical model to describe the marine tethered systems dynamics, taking into account the effect of torsion, is important and relevant. The mathematical model of the marine tethered systems dynamics was improved and solved by accounting for the generalised forces of the torsion rigidity of the flexible link, using an algorithm and computer program. The influence of the bending and torsional rigidity of the FL on its deflection and tensile strength were considered based on the example of two problems. The developed program’s working window image shows the simulated parameters and the initial position of the flexible link. The results show that torsion has almost no effect on the shape of the a flexible link’s deflection in the X0Z plane, but leads to a deviation from the X0Z plane when calculating the static deflection of the flexible link. When the carrier vessel is stationary and the submersible vehicle has no restrictions on movement and has positive buoyancy, torsion leads to a three-dimensional change in the shape of the flexible link both in the X0Z plane and in the X0Y plane. The tension force of the flexible link along its length is distributed unevenly, and the torsion of the flexible link can lead to significant changes in its shape, the trajectory of towed objects, and the forces acting on the elements of the marine tethered systems
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CAO, ZHEN-BIN, and YI-SHI DUAN. "EXTRA DIMENSIONS WITH NONTRIVIAL TORSION AND SPINS OF COSMIC STRINGS." Modern Physics Letters A 24, no. 14 (May 10, 2009): 1147–57. http://dx.doi.org/10.1142/s0217732309028369.
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As two generalizations of Einstein's general relativity, the nontrivial spacetime torsion and the compact extra dimensions have been largely studied in the literature. In this paper, by combining a torsioned Kaluza–Klein scheme and the field-theory cosmic string theory, we discuss that a higher-dimensional torsion component can be expressed in terms of the usual four-dimensional field strength two-form, and this torsion form can then get trapped into the cores of the cosmic strings and further relate to the intrinsic spins of the strings.