Torsional Effects Research Articles

Stress torsional magneto-impedance effect and mechanical properties of Co-based metallic microfibers

GMI characteristics of Co-based metallic microfibers under different stresses are tested by stress torsional magneto-impedance comprehensive platform. The internal stress distribution of microfibers is simulated with ANSYS finite element software and the fracture mechanism is analyzed based on fracture morphology. The experimental results indicate that tensile stress can enhance the GMI effect of metallic microfibers, and the significant [ΔZ/Zmax]max of 293.63% at a frequency of 3 MHz is obtained under the tensile stress of 482 MPa. The simulation results demonstrate that the internal stress concentration occurs at clamping end under tensile stress, and which accumulating on the surface of microfibers after applying torsional strain, thus weakening GMI effect. The fracture morphology will change with external stress, some vein-shaped patterns and molten drops can be seen in the cross-section under tensile stress, and the helical vein-shaped patterns appear with the application of torsional strain. In addition, the circular domain wall energy will be increased due to magnetoelastic anisotropy has been affected by tensile stress, which promotes an increment of circular magnetic permeability, thus improving the GMI effect of microfibers. However, the appearance of helical anisotropy after torsional strain is added will weaken the circular domain wall energy.

Seismic design and engineering practice of a 10‐story self‐centering precast concrete wall structure

SummaryThe increasing expectation of structures capable of fulfilling the requirements of minimizing post‐earthquake repair or re‐occupancy has led to the emergence of damage‐control technologies. In recent years, self‐centering precast concrete wall systems that are characterized by low damage as well as full prefabrication have become a popular topic. Previous research has shown that the system is not only capable to reduce the construction time but also has the characteristics of small residual displacement and quick restoration of normal service function after a major earthquake event. Nevertheless, there is still much to be studied for high‐rise buildings and practical engineering applications. This paper introduces the process of self‐centering precast concrete wall systems from conceptual design to detailing and construction aspects of a 10‐story case study building. Specifically, the hybrid type of unbonded post‐tensioned wall is adopted with mild steel functioning as the energy‐dissipating component. The design and construction of mild steel take into account the requirements of both building function and replaceability. In addition, the lateral resisting system is decoupled from the gravity system using isolated joints for wall‐to‐floor connection. Various factors such as higher mode effects, torsional effects, and wind loads are considered in the design process in order to achieve the overall high performance of the structure. Finally, the numerical model of the designed structure is established and analyzed under both static and dynamic loading. Results show that the self‐centering wall structure studied in this paper has satisfactory seismic performance, i.e., each component and joint can work to achieve the function as expected, and has broad engineering application prospects in the future.

ANALYSIS OF MECHANICAL CHARACTERISTICS OF KNOT CONNECTIONS IN BUILDING STRUCTURES BASED ON ANSYS SIMULATION

The most common cross-section – the joining of two symmetrical I-beams – is investigated in this work. The transmission of force on the node connection in the form of a multi-bolt connection, welded connection, welded connection through the lining is modeled. The effect of node connections on the stress-strain state of the spatial structure made of thin-walled open section rods, torsional effects depending on the fastening of the elements is studied. The calculation of the structure is reduced to the determination of the stresses and displacements in the fastening nodes, by which the change in the mechanical characteristics of steel is then determined.

On the thermal stresses in chiral porous elastic beams

This paper is concerned with the strain gradient theory of porous thermoelastic solids. We study the deformation of isotropic chiral cylinders subjected to a temperature field that is linear in the axial coordinate. It is shown that the solution can be reduced to the study of two-dimensional problems. The results are used to investigate the deformation of a circular cylinder subjected to a uniform temperature variation. In contrast to the case of achiral materials, the thermal field in chiral cylinders produces torsional effects.

Fragility curves for assessment of seismic vulnerability of buildings on slopes

Step-back and step-back setback configurations are the common structural systems found in the hilly regions of the Indian Subcontinent. These buildings are often subjected to torsional effects under the action of earthquakes due to different foundation levels. The present study focuses on the probabilistic determination of the seismic vulnerability of step-back and step-back setback configurations and the effects of live load eccentricity. Incremental Dynamic Analysis (IDA) is used to obtain the dynamic capacity curves, which capture the torsional effects. A set of 11 ground motion time histories have been selected and scaled to the target response spectrum. Fragility analysis is carried out after obtaining the dynamic capacity curves, and the fragility curves are obtained for five limit states, namely Operational Performance (OP), Immediate Occupancy (IO), Damage control (DC), Life Safety (LS), and Collapse Prevention (CP) as per FEMA 273. Comparison of the fragility curves indicates the suitability of the step-back setback configuration vis a vis step-back configuration, as it yields a low probability of damage. The short column effects, along with live load eccentricity, increase the vulnerability to damage.

Effect of Lower Extremity Torsion on Clinical Outcomes After Medial Patellofemoral Ligament Reconstruction and Tibial Tubercle Transfer for Recurrent Patellofemoral Instability

Background: Increased femoral torsion (FT) or tibial torsion (TT) has been suggested to be a potential risk factor for recurrent patellofemoral instability. However, the influence of increased FT or TT on the postoperative clinical outcomes of recurrent patellofemoral instability has rarely been investigated. Purpose: To assess the effect of increased FT or TT on postoperative results in patients with recurrent patellofemoral instability after combined medial patellofemoral ligament reconstruction (MPFLR) and tibial tubercle transfer, along with the influence of other risk factors. Study Design: Cohort study; Level of evidence, 3. Methods: Out of 91 patients, the study’s analyses included 86 patients with recurrent patellofemoral instability who were treated with MPFLR and tibial tubercle transfer and enrolled between April 2020 and January 2021. FT and TT were assessed using preoperative computed tomography images. According to the torsion value of FT or TT, patients were categorized into 3 groups for each of FT and TT: group A (<20°), group B (20°-30°), and group C (>30°). Patellar height, femoral trochlear dysplasia, and the tibial tuberosity–trochlear groove (TT-TG) distance were also assessed. Patient-reported outcome scores (Tegner, Kujala, International Knee Documentation Committee [IKDC], Lysholm, and Knee injury and Osteoarthritis Outcome Score [KOOS]) were evaluated pre- and postoperatively. Clinical failure of MPFLR was recorded. Subgroup analysis was conducted to evaluate the effect of increased FT or TT on the postoperative outcomes. Results: A total of 86 patients were enrolled with a median follow-up time of 25 months. At the final follow-up, all functional scores improved significantly. Patella alta, high-grade trochlear dysplasia, and increased TT-TG distance did not have any significant effect on the postoperative functional scores. Regarding FT, subgroup analysis indicated that all functional scores of group C were lower than those of groups A and B except the KOOS knee-related Quality of Life score. For TT, group C had lower scores than group A for all functional outcomes except Tegner and KOOS Quality of Life and lower scores than group B for Kujala, IKDC, KOOS (Symptoms and Sport and Recreation subscales), Tegner, and Lysholm scores. The comparison between group A and group B, whether for FT or TT, revealed no significant differences. Conclusion: For patients with recurrent patellofemoral instability, increased lower extremity torsion (FT or TT >30°) was associated with inferior postoperative clinical outcomes after combined MPFLR and tibial tubercle transfer.

Nonlinear Analysis on Torsional Strengthening Of Rc Beams Using Cfrp Laminates

This research is devoted to investigate the behavior and performance of reinforced concrete beams strengthened with externally bonded Carbon Fiber Reinforced Polymer (CFRP) laminates under the effect of torsion. In this study a theoretical analysis has been conducted using finite element code ANSYS. Six previously tested beams are used to investigate reinforced concrete beams behaviorunder torsion, two of them are solid and the rest are box-section beams. Also, two beams are without CFRP reinforcement, which are used as control beams for the strengthened one, and the other four beams are strengthened with CFRP laminates with different number of layers and spacing. Numerical investigation is conducted on these beams, and comparisons between the available experimental results for these beams and numerical results from the current study are made. Conclusions from these comparisons are presented and discussed. An increase of about 15.6% in the ultimate torque for the solid beam and of about 9.8% in the ultimate torque for the box-section beam is observed after using the CFRP strips. A parametric study is carried out to study the torsional behavior of RC beams having different number of CFRP layers and concrete compressive strength; also U-wrap for the CFRP configuration is investigated.

Emergent geometry, torsion and anomalies in non-relativistic topological matter

I review and discuss aspects of the interplay of emergent geometry and anomalies in topological semimetals and insulators, focusing on effects of torsion. This correspondence identifies torsional topological responses in terms of anomalies and anomaly related hydrodynamic phenomena involving gauge fields and geometry. I discuss how torsional emergent geometry arises from elastic deformations in crystalline materials and how this background couples to thee low-energy continuum models inherited from lattice models, utilizing the semiclassical expansion. Via the coupling of momentum space topology and emergent vielbein geometry, non-relativistic topological matter can realise new geometrical responses of mixed gauge-gravitational character. The topological low-energy torsional responses depend momentum space geometry, lattice momenta and the regularization and UV completion, provided by the non-relativistic physics and symmetries of topological materials.

The Effect of High-Pressure Torsion on the Structure and Mechanical Properties of the Al–Ca–Cu Alloy

The Effect of High-Pressure Torsion on the Structure and Mechanical Properties of the Al–Ca–Cu Alloy

Mathematical Model of Flexible Link Dynamics in Marine Tethered Systems Considering Torsion and its Influence on Tension Force

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

Damage Detection of High-Speed Railway Box Girder Using Train-Induced Dynamic Responses

This paper proposes a damage detection method based on the train-induced responses of high-speed railway box girders. Under the coupling effects of bending and torsion, the traditional damage detection method based on the Euler beam theory cannot be applied. In this research, the box girder section is divided into different components based on the plate element analysis method. The strain responses were preprocessed based on the principal component analysis (PCA) method to remove the influence of train operation variation. The residual error of the autoregressive (AR) model was used as a potential index of damage features. The optimal order of the model was determined based on the Bayesian information criterion (BIC) criterion. Finally, the confidence boundary (CB) of damage features (DF) constituting outliers can be estimated by the Gaussian inverse cumulative distribution function (ICDF). The numerical simulation results show that the proposed method in this paper can effectively identify, locate and quantify the damage, which verifies the accuracy of the proposed method. The proposed method effectively identifies the early damage of all components on the key section by using four strain sensors, and it is helpful for developing effective maintenance strategies for high-speed railway box girders.

Multistructural torsional anharmonicity and pressure-dependent kinetic studies on methanol/ethanol reaction with amino radical: Implication for combustion modeling

The blending of ammonia with alternative fuel alcohols has recently received increasing interest and it has been shown that their cross-reactions significantly influence the ignition process. In the present work, the detailed electronic structure calculations and kinetic studies for the reactions of CH3OH/C2H5OH with NH2 were performed. The rate constants were calculated by Master Equation/Rice–Ramsperger–Kassel–Marcus (ME/RRKM) over a pressure range of 10−1–105 Torr for the pressure-dependent effect caused by reactant complex. The multistructural torsional anharmonicity effects of the reaction were analyzed and the high-pressure limiting rate constants were calculated over a wide temperature range of 250–2000 K by using multistructural variational transition state theory. All calculations considered the tunneling effect. The results show that the CH3OH/NH2 system exhibits pressure-dependent below 550 K, while the pressure-dependent of the C2H5OH/NH2 system can be safely neglected. Besides, the multistructural torsional anharmonicity effect is pronounced for the C2H5OH/NH2 system, especially at intermediate and high temperatures. The channel for the formation of CH2CH2OH is underestimated and the branching ratio of this channel exceeds that of CH3CH2O and CH3CHOH under the multistructural influence at high temperatures. Thus, we updated the kinetic model and further investigation on ignition delay times and sensitivity analysis. The discrepancies in rate constants caused by the kinetic methods mentioned above seems to have a non-negligible effect on the combustion modeling.

Experimental Investigation of Compound Effect of Flexural and Torsion on Fiber-Reinforced Concrete Beams

Fiber-reinforced concrete is widely acknowledged for its ability to resist cracking effectively and limit its propagation. By preventing cracks from spreading, the addition of fiber composites to concrete can enhance its extensibility and tensile strength, not only at the initial point of cracking but also at its maximum capacity. Additionally, the fibers in fiber-reinforced concrete are capable of binding the matrix, even when exposed to significant cracking. However, there is limited information available about the behavior of fiber-reinforced concrete under a bending moment combined with torsion. This study aims to investigate the structural behavior of fiber-reinforced concrete members subjected to a bending moment with a torsion to moment ratio equal to 1. Synthetic and steel fibers of 1.0% content with different lengths (19, 35, and 55 mm for synthetic fiber and 13 mm for straight and hook steel fibers) were mixed with concrete mixtures to examine the effects of fiber lengths and types on the concrete beam performance. Test results indicated that the fiber-reinforced concrete beams showed higher cracking moments than the normal-strength concrete beam. The steel fiber with a hooked configuration reinforced beam showed increased moment capacity and total torsional toughness higher than that of the straight steel fiber-reinforced beam. The synthetic fiber of a 55 mm length reinforced beam exhibited the highest first-crack and ultimate moment values among other tested beams. The test results were compared with past research models for the moment capacity of beams under the compound effect of bending and torsion and we modified these values with another factor that represented the fiber length influence on beam capacity, as suggested in past research. The comparison between the ultimate moment of the test results and the moment predicted from the modified past research model presented a good correlation.

Numerical investigation on the pull-out capacity of suction anchors in sand considering torsional and mooring line effects

Torsional pullout of suction anchors may occur during installation due to improper positioning or deviations caused by current forces, but less attention has been paid to the effect of torsion on the pull-out capacity of suction anchor in existing literatures. This paper therefore numerically investigates the pull-out capacity and failure mechanism of suction anchors in sand considering both torsional and mooring line effects using the advanced SIMSAND constitutive model. It is found that considering torsional influence causes a significant reduction in the pull-out capacity of suction anchor in sand under horizontal and inclined loading. The case with the optimal padeye depth of 0.7L produces the largest pull-out capacity and the greatest reduction in the pull-out capacity due to torsion. The dimensionless pull-out capacity for the case without mooring line is approximately 24% higher than or almost twice that of the case with mooring line in scenarios without or with torsional condition. Based on the findings, a new framework for estimation of the pull-out capacity of the suction anchor at the optimal padeye depth in sand considering torsional and mooring line effects is finally proposed which may benefit the design of suction anchor in scenarios with torsion in the real practice.

Femoral Anteversion Is Associated With a Thinner Anterior Capsule in Patients With Femoroacetabular Impingement Syndrome

To measure femoral torsion on computed tomography images in patients with femoroacetabular impingement syndrome and explore whether femoral torsion was significantly correlated with anterior capsular thickness. Prospectively collected data of surgical patients were retrospectively reviewed. Only patients aged 16 to 55 years who underwent primary hip surgery were included in this study. Patients with a history of revision hip surgery, previous knee surgery, hip dysplasia, hip synovitis, and/or incomplete radiographs and medical records were excluded from the study. Femoral torsion was measured via computed tomography imaging using transcondylar slices of the knee. Anterior capsular thickness was measured using oblique-sagittal sequences on a 3.0-T magnetic resonance imaging system. The association between anterior capsular thickness and related variables, including femoral torsion, was assessed via multiple linear regression. The patients were then divided into 2 groups to further confirm the effect of femoral torsion on capsular thickness: Patients in the study group had hips with moderate (20°-25°) or severe (>25°) antetorsion, whereas patients in the control group had hips with normal torsion (5°-20°) or retrotorsion (<5°). Anterior capsular thickness was also compared between the 2 groups. A total of 156 patients (89 female patients [57.1%] and 67 male patients [42.9%]) were finally included in the study. The mean age and body mass index of the included patients were 35.8 ± 11.2 years and 22.7 ± 3.5, respectively. The mean femoral torsion for the entire study population was 15.9° ± 8.9°. Multivariable regression analysis showed that femoral torsion (P < .001) and sex (P= .002) were significantly correlated with anterior capsular thickness. Propensity-score matching yielded 50 hips in the study group and 50 hips in the control group on femoral torsion subanalysis. The results showed that anterior capsular thickness was significantly smaller in the study group than in the control group (3.8 ± 0.5 mm vs 4.7 ± 0.7 mm, P < .001). Femoral torsion is significantly inversely correlated with anterior capsular thickness. Level III, retrospective comparative study.

Gravitational waves in Einstein–Cartan theory: On the effects of dark matter spin tensor

This article studies the effects of an arbitrary dark matter spin tensor on the propagation of gravitational wave amplitude in the context of Einstein–Cartan theory. We choose to work with an arbitrary spin tensor because, given our ignorance of the nature of dark matter, it is sensible not to make further hypotheses on its spin and not to assume any particular model for its spin tensor (or its vanishing). The analysis focuses on a “weak-torsion regime”, such that gravitational wave emission, at leading and subleading orders, does not deviate from standard General Relativity. We show that, in principle, the background torsion induced by an eventual dark matter spin component could lead to an anomalous dampening or amplification of the gravitational wave amplitude, after going across a long cosmological distance. We assess the importance of this torsion-induced anomalous amplitude propagation for binary black hole mergers in a way as model-free as possible in Einstein–Cartan gravity. It is possible to prove that at its best, for realistic late-universe cosmological scenarios, the effect is tiny and falls below detection thresholds, even for near-future interferometers such as LISA. Therefore, detecting this effect may not be impossible, but it is still beyond our technological capabilities. As a model-independent result in the Einstein–Cartan context, it also implies that mergers are robust standard sirens without considering any potential dark-matter-induced torsional effects.

Assessment of the Seismic Vulnerability of a Multi-storey RC Structure with Plan Irregularity: A Case Study

A nine-story reinforced concrete dual system (wall-frame) building located in Bucharest, categorized as plan-asymmetric and designed according to the provisions of Romanian and European codes was studied. The criteria for regularity in plan were verified comparatively according to three codes (Eurocode 8, ASCE 7-16 and the Romanian seismic design code P100-1-2013). The seismic behaviour of the studied building was further investigated by detailed nonlinear static analyses (pushover) and nonlinear dynamic analyses performed on the 3-D building model, for various load patterns and spectrum-compatible ground motion records, respectively. The seismic vulnerability of the building was estimated based on the structural vulnerability index, determined from the nonlinear analyses. The study highlighted the significant effects of the overall torsion on the investigated parameters, in particular on interstory drifts and roof displacements, but also on the seismic vulnerability index.

Seismic vulnerability assessment of steel storage tanks protected through sliding isolators

AbstractAn adequate seismic protection of steel storage tanks of industrial, chemical and petrochemical plants is essential since potential consequences of failures, besides the economic losses, can be catastrophic for the environment and for people living nearby. Among the most common damages suffered by steel tanks in recent earthquakes, there are the elephant‐foot‐buckling of the perimeter wall and the tanks’ uplift or overturning. Due to the uncertainties related to the estimation of the mechanical properties of filled tanks and related seismic loads (i.e. dynamic overpressures generated by the content), conventional design approaches may lead to unsafe or, on the contrary, oversized solutions. Among effective alternatives, base isolation through Curved Surface Slider isolators (CSSs) offers some valuable advantages like high load bearing and displacement capacity with compact dimensions, independence of the oscillation period on the supported mass, and minimisation of torsional effects. Despite being neglected by most common commercial FEM codes, as a drawback, recent studies pointed out that the initial peak of friction force at CSSs’ motion breakaway can lead to significantly increased lateral deformations and accelerations of the superstructure. Within this framework in this study, a refined numerical model is developed in OpenSees FEM code, and an exhaustive parametric study is carried out to investigate the effect of the breakaway on isolated tanks providing some useful insights for the selection of the most suitable isolators.

A new perspective into torsional inelastic response of actively controlled irregular multistorey buildings

The nonlinear dynamics of irregular structures is influenced by both local and global torsional effects. In order to capture the inelastic structural response, the concept of plastic hinges is one of the most used tools due to its numerical efficiency. However, the combined effect of bending and torsion into the inelastic domain is scarcely illustrated in literature. In this paper, the recently developed 3D Force Analogy Method is augmented with an algorithm to consider axial force – biaxial bending moment –torque interaction. A structure having both plan and elevation irregularities is considered as a case study to illustrate the benefits of the proposed algorithm. The structural control concept is further implemented in the attempt to improve structural performance of irregular structures. A non-commercial Matlab/Simulink code is developed for the scopes of this paper.

Comparison of torsional damage and size effects of BFRP- and steel-reinforced concrete beams with different stirrup ratios

To better understand the differences in torsional performance and size effect between BFRP-reinforced concrete (BFRP-RC) beams and reinforcement concrete (RC) beams, numerical tests on the pure torsional performance of BFRP-RC and RC beams was carried out by a 3D meso-scale numerical method. The effects of beam height, stirrup ratio, and reinforcement type on torsional damage and the size effect law of beams were analyzed. Furthermore, the simulation results were compared with national codes and Jin et al.'s size effect law. The results indicate that: 1) With the beam size increase, the torsional capacity and ductility of BFRP-RC beams decrease more than that of RC deep beams. 2) Stirrups can not only improve beams' torsional strength but also weaken the torsional size effect, but the effect of BFRP stirrups is not as evident as that of steel stirrups. 3) The safety reserve of calculation results in national codes is insufficient for the torsional capacity of large-size beams. Moreover, the contribution of concrete should be reasonably considered in the pure torsional capacity of concrete members. 4) The size effect law proposed by Jin et al.'s can well describe the torsional size effect of BFRP-RC beams and RC beams.