Torsional Moment Research Articles

Finite Tube Method for buckling analysis of tubular members using Fourier-approximation for the displacements

In this paper an efficient numerical method for the static analysis of cylindrical tubes is introduced. The method is designed for the linear buckling analysis of wind turbine support towers which are, most typically, built up from conical and/or cylindrical cans. Accordingly, the developed method uses cylindrical tube segments as elementary building blocks, along with specialized shape functions, and is named the Finite Tube Method. Within a tube segment the displacements are approximated by two-dimensional Fourier series. The curved nature of the surface is directly considered in the kinematic equations. The segments are joined and/or supported to the ground by constraint equations or by elastic links. In the current implementation internal stresses are determined in a simplified way: the circumferential stress distributions are calculated from the internal forces/moment by classic strength of material formulae, while the longitudinal distribution within each segment is quadratic. The considered internal forces/moments are: normal force, shear force, bending moment, and torsional moment. The internal forces can be arbitrarily combined. In the paper the underlying derivations are briefly summarized, then the method is demonstrated and validated by numerical examples, comparing the results to analytical and alternative numerical solutions. The authors are actively developing the method and will provide future work on utilization of the method for buckling mode identification and decomposition, as well as practical advancements to make the method a useful tool in the engineering design and analysis of wind turbine support towers.

Finite elemental assessment of torsional behavior of RC beams having different shear reinforcement

In this paper, the torsional behavior of 8 beams in 4 categories with 2 different ultimate concrete compressive strengths (22.92 MPa and 43.47 MPa) was evaluated, and the best alternative of shear reinforcement pattern compared to the conventional non-welded rectangular stirrup beam (NRSB) was determined. 4 types of beams were modeled using SolidWorks, namely—Non-welded Rectangular Stirrup Beam (NRSB), Welded Rectangular Stirrup Beam (WRSB), Normal Welded Warren Truss-shaped Beam (NWWTB), and Flipped Welded Warren Truss-shaped Beam (FWWTB). The dimension and weight of reinforcement were kept the same for all beams. After simulating using ANSYS, it was seen that WRSB specimens had the largest torsional moment capacity, while NWWTB in normal orientation showed marginal improvement compared to NRSB.

Combined bending-torsion and compression-bending-torsion behaviours of reinforced concrete-filled thin-walled corrugated steel tubes

Reinforced concrete-filled thin-walled galvanized corrugated steel tube (RCFCST) is a novel composite member that has application potential in extremely corrosive environments and seismic activity regions. A series of preliminary works have been conducted on its compressive, flexural, shear, and torsional behaviour. However, the combined loading condition is almost inevitable in practice. The correlations between the flexural and torsional behaviour of RCFCSTs are unique due to the special spiral corrugated profile, which is unclear and needs to be addressed. This paper, therefore, presents an experimental investigation of the RCFCST under combined bending-torsion and compression-bending-torsion loads, encompassing the main test variables of torsion-to-bending ratios, torsional directions, and axial compression ratios. The loading set-up and instruments have been introduced in detail. The failure modes, lateral load versus lateral displacement curves, bending moment versus flexural lateral displacement curves, torsion moment versus torsional angle curves, and strain distributions are carefully addressed. The working mechanisms of the RCFCST under monotonic combined loads are discussed, with a particular explanation of the dependent behaviour on the torsion-to-bending ratios and torsional directions. The applicability of the existing design methods for the bearing capacity of RCFCST specimens under combined loads is examined carefully, with specific design suggestions proposed.

Theoretical and experimental comparison between straight and curved continuous box girders

Abstract The curvature causes a variation in the deflection of the outer and inner sides. The effect of curvature was investigated by casting and testing two specimens with the same section – one straight and the other horizontally curved continuous box girder. ABAQUS software was used to numerically model the box girder in order to verify the model and investigate additional parameters. Numerical modeling is successful with less effort, cost, and time because good results are obtained. The effect of the span-to-depth ratio, the compressive strength of concrete, and the percentage of stirrup steel reinforcement was studied numerically. Increasing the height, compressive strength, and percentage of stirrup steel led to a significant increase in load capacity and stiffness. The load capacity in the curved specimen decreased by 11% compared to the straight one due to the effect of torsional moments. A mathematical model was proposed based on the theory of strut-and-tie modeling (STM), where the span was divided into several panels, the effect of torsion was added, and then the results were compared with the traditional sectional method according to ACI and CEB-FIB. For the straight specimen, the sectional ACI, CEB-FIB, and STM methods were used, which gave theoretical results less than the experimental by 31, 48 and 13%, respectively. For the curved specimen, to get closer to reality, the sectional and STM methods were modified by adding the effect of torsion, and the results were less than the experimental tests by 43, 61 and 22%, respectively.

Deformation mitigation and twisting moment control in space frames

Over the last five decades, space frames have centered on the modernization of touristic zones in view of architectural attractions. Although attempts to control joint movement and minimize axial force and bending moment in such structures were made sufficiently, twisting moments in space frames have been underestimated so far. In space frames, external load or restoring the misshapen shape may cause twisting in members. We herein developed a robust computational algorithm to reduce the induced torsional moment through shape restoration within a desired limit by changing the length of active bars that are placed in space frames. Applying optimization algorithms like interior-point and Sequential quadratic programming (SQP), a direct correlation was pursued between bar length alteration and twisting in structural members. A numerical model of a single-layer space frame resembling an egg captures the twisting moment in all members, achieving a specified limit. The overall length change of the active members using an iterative process based on a heuristic that considers a threshold on the minimum length change of the active members.

Evaluation of the Tracker Tool on the Cessna 172s Throttle Using Simulation

The throttle is a device on the Cessna 172s training aircraft which is used to increase the amount of air used during combustion. To help overcome difficult throttle adjustments, special tools are needed in the form of a tracker. The existence of representative and useful tools to make things easier and save costs is really needed, therefore research to create work aids currently needs to be increased. Tool testing is also very important in knowing the maximum working point of the tracker tool which can determine properties such as shear elastic modulus, torsional yield strength and rupture modulus. The torsion test results consist of two parameters, namely the torsional moment parameter and the shear stress parameter. The tool that has been created in this research will analyze torsional strength using simulation.

Efficiency of shear connectors under combined shear and torsion

The connection of steel elements to concrete is typically achieved through embedded shear connectors (anchors) placed at the interface of concrete and steel. These shear connectors come in various types, such as headed studs, welded or coupled rebars, shear lugs, or a combination of these, designed to handle large shear forces. Shear connectors primarily resist shear forces and bending loads. However, when the load is not applied along the centroid of the shear connector, it generates a torsional moment in addition to shear- and flexure-induced moments, impacting the performance of shear connectors. To address this phenomenon, this experimental study assesses the behavior of shear connectors, including studs, shear lugs, and rebars, both individually and in combination, under three different load eccentricities relative to anchors spacing connectors (0, 0.25, 0.50, and 0.75). The results are then compared with the control specimen (without eccentricity). The findings revealed that vertical shear lugs can significantly enhance the shear capacity, and ACI 318-19 is conservative in this regard by 41.5% for a relative load eccentricity of 0.75. Nonetheless, it gives good estimations of the shear capacity of connectors without vertical shear lugs. HIGHLIGHTS Contributing to the very limited data on the performance of anchors under the combined action of shear and torsion. ACI 318-19 [1] provides reliable estimations of shear strength for studs/rebars, both with and without eccentricity. However, it tends to be conservative by 41.5% (for a relative eccentricity of 0.75) when horizontal and vertical shear lugs are utilized.

Mathematical model of fatigue degradation of cylindrical piezo element of linear micro piezo motor

In the article, a mathematical model has been constructed and investigated by analyzing the problem of disintegration during torsion of the cylindrical shaped piezo element in the linear piezoelectric engine. Nonlinear differential equations expressing the expansion of the disintegration surface formed during the torsion of the piezo element under the influence of variable torsional moment have been formulated. Guidelines determining the initial degradation period for the development of the disintegration process have been obtained, and based on the developed mathematical model, displacement curves of the disintegration surface motion have been established.

Torque expression of superelastic NiTi V-Slot and conventional stainless steel orthodontic bracket-archwire combinations - A finite element analysis

BackgroundTo investigate the torque expression of conventional stainless steel (SS) brackets in combination with rectangular SS archwires and nickel-titanium (NiTi) V-slot brackets in combination with V-shaped NiTi archwires using finite element analysis (FEA). MethodsCAD models were created for a conventional bracket and rectangular archwires with dimensions of 0.018″x0.025″ and 0.019″x0.025″, and for a V-slot bracket and V-shaped archwires with heights of 0.55 mm, 0.60 mm and 0.70 mm. FEA was performed using Ansys 2022R2 software to assess the forces and moments during simulated torsion of the archwires in the brackets between 0° and 25° with varying interbracket distances and free path lengths. ResultsThe V-slot bracket-archwire combination exhibited force transmission and moment generation within 1° of torsion. The transmissible force increased with the torsion angle, but showed an upper limit of about 13–14 Nmm. The SS bracket-archwire combination showed negligible forces and moments for simulated torsion between 0° and 15°. At torsions of 25°, moments of 12 Nmm and 14 Nmm occurred for the 0.018″x0.025″ and 0.019″x0.025″ archwire dimensions, respectively. ConclusionsThe V-slot bracket-archwire combination is effective in expressing torque and preventing both over- and under-activation. Conventional bracket-archwire combinations showed torsional losses due to play between 10 and 15°, depending on the dimensions of the respective archwire, and no upper torsional moment limit.

EXPERIMENTAL DETERMINATION OF TORQUE FOR THE DRILLING OFAL7SIMG ALLOY

The productivity of a machining process is closely related to the value of the cutting force.For the calculation of the cutting forces, a series of models have been developed to allow the determination of these forces according to the machined material and the specific conditions in which the process is carried out. Usually, for a better approximation of the value of the cutting force, the unitary specific cutting force is used, which depends on the machined material. For common materials, the values of specific unitary cutting forces are presented in the specialized literature, but for less frequently used materials, for example, those with reduced machining properties, the respective values are difficult, sometimes impossible to find. In this paper, determining the unitary specific cutting force for an aluminum alloy with a high silicon content is intended, recognized as difficult to machine. The determination of the value of this force is done starting from the measured values ofthe torsional moment at the drills.

Pengaruh Variasi Spring Plat dan Massa Roller Terhadap Torsi dan FC Pada Motor 150 cc

In Indonesia, there are two types of motorcycle transmissions: manual and automatic. Users prefer automatic transmissions due to convenience and fuel efficiency. Automatic transmissions, such as CVT, CVT utilizes force for smooth and continuous gear ratio changes. CVT has disadvantages because unlike manual motors that have greater torque, especially on motorbikes that are three years old or more, such as poor acceleration at low to medium revolutions and wasteful fuel. This study aims to determine how the effect of adding spring plate and roller mass variations on torque and fuel consumption. This research uses a quantitative method with an experimental approach, by testing the independent variable to determine the results of the dependent variable. The result of this research is the use of lighter rollers can increase fuel consumption but the torque is getting smaller, because the use of lighter rollers has a fast rotation response so that the crankshaft in rotating the roller housing pulley is also lighter so it does not require a lot of fuel. While the use of heavier rollers coupled with spring plates also increases torque because the displacement ratio is faster, the torsional moment will be large which causes the torque to increase.

Enhancing torsional performance of reinforced concrete beams: a comparative analysis of shear reinforcement strategies

Torsion failure poses a critical threat to the structural integrity of reinforced concrete, particularly in seismic hazard zones. This study aims to overcome this difficulty by conducting a thorough examination of the torsional characteristics of Reinforced Cement Concrete (RCC) beams. This study examined the torsional characteristics of various RCC beams by utilizing different configurations of shear reinforcements. The objective was to determine an effective alternative shear reinforcement configuration in comparison to the traditional Non-welded Rectangular Stirrup Beam (NRSB). Comparing three types of beams, namely NRSB, Welded Rectangular Stirrup Beam (WRSB), and Welded Warren Truss Beam (WWTB), a novel warren truss-shaped shear reinforcement was introduced. All beams were constructed with consistent dimensions of concrete and uniform weights of reinforcement, including 16 mm bars for the top and bottom longitudinal reinforcement and 10 mm bars as shear reinforcements. Two separate concrete mix ratios were evaluated, specifically 1:1.5:1.5 and 1:2.5:2.5 (by volume) respectively. Theoretical calculations based on elastic theory were used to determine the angle of twist for each beam. The torsional moment resistance of WRSB and WWTB was found to be 4.4% and 1% higher, respectively, compared to the traditional NRSB, while using a mix ratio of 1:1.5:1.5. Regarding the alternative mixture ratio, the torsional moment for WRSB was 10% more, whereas for WWTB it was 2.4% less. As a result, the WRSB specimens exhibited the highest torsional moment for both mix ratios, but the NRSB and WWTB specimens had comparable values.

A Study on the Impact of Low-Frequency Random Loading and Unloading on Silo Structures

To investigate the development of cracks in the walls of reinforced concrete silos under feeding–discharge cycle loading, their causes, and their fatigue life during dynamic loading, a study was conducted using a combination of in situ monitoring and numerical simulation analysis. The following conclusions were drawn: during the loading and unloading process of the silo, the time of occurrence of the minimum pressure points follows a 4:3 ratio; extreme points are approximately 15 min apart; the minimum pressure increases during material addition and decreases during material subtraction; and the load in the non-discharge area is 1.43 times that of the load in the discharge area. That is, at the same elevation, the load borne by the silo wall is uneven, with fluctuations and rotational effects occurring. Under such uneven load conditions, the silo wall experiences significant bending and torsional moments, causing excessive local tension and leading to cracking. Our analysis showed that the most unfavorable load condition occurs when discharge ports 5 and 7 are operating simultaneously, which causes the maximum tensile damage to the silo wall. For the first time, a fatigue life prediction model for reinforced concrete silos was proposed, and the accuracy of this prediction method was verified based on actual conditions.

Comparison Between the Behavior of Reinforced Concrete Beams and RPC Beams Under Bending and Torsion Moments

Abstract Typically, the beams were subjected to bending and torsion moments especially at building edge. However, most of the studies focus on the flexural or torsional behavior of the beams independently, and few studies investigated these two combined effects. The research intends to explore the structural behavior of eight 1500mm x 200 mm x 150 mm rectangular beams that were tested under the combined effects of bending and torsional moments, with four main values of (T/M) ratio: pure bending, pure torsion, and two combined cases. The research investigates the effect of using reactive powder concrete (RPC) on beam behavior compared to normal concrete (NC). The outcome demonstrates that using RPC in beams instead of NC beams will significantly increases the cracking capacity by 136.4% in the case of pure bending and significantly increases the ultimate capacity by 118% in the case of combined moments with (T/M = 1). Also, using RPC leads to significant reduction in deflection and rotation values especially after beam cracking. RPC reduces compressive concrete strain and values of strains in longitudinal and transverse reinforcement especially in advanced loading stages.

Observation and modelling of asymmetric loading on large offshore wind turbines in wake conditions

We study the dynamic loading of a wind turbine in the presence of a single wake in the wind speed range of 8 to 12 m/s and a wind direction range of 40° around the wake alignment direction. Measurement data from an offshore wind farm in the North Sea is compared to simulations. Damage equivalent loads and order spectra are compared. Five wake models are used: Frandsen added turbulence model, three parametrizations of DWM, and LES wake simulations. A new parametrization of DWM with an added wake distortion model is introduced improving the wake effect on fatigue loading of tower top torsion and tilt bending moment. All DWM models compare more favourably to measurements than the added turbulence model, but only the wake distortion model allows for a conservative fatigue assessment on all channels. LES has the potential to be even more accurate in capturing the spectral response in wake, but results are preliminary as limited LES data was available.

Considerations for the structural design of wind turbine towers: A practical application

AbstractAiming to achieve efficient structural performance, this article presents a methodology for the design of the shell structure and dimensioning of the connections of an S355J2 tubular steel tower with a height of 80 m, compatible with a SWT‐2.3‐93 wind turbine. The tower is made up of three segments, interconnected by flanged connections made of high‐strength steel. The analysis considers various load cases, taking into account stress and resistance in different directions, as well as designing connections using Petersen's theory, according to maximum strength and fatigue criteria. The results indicate that the circumferential stresses are nearly negligible compared with the resistant stresses, while the shear stress is significantly higher at the base due to the torsional moment. Meridional stress determines the stability of the structure, requiring consideration of internal pressure for safety. Maximum stress values range from 135.00 to 168.47 MPa, depending on the location along the tower height. Flanged connections meet the strength and fatigue criteria, with the first flange enduring 63.0% of the fatigue effect and the second, 39.7%. Therefore, the results provide reliable information and methodologies for tower design, contributing to the practical and efficient development of these structures.

Ultimate torsional moment of dry horizontal joint for prefabricated concrete tower

SummaryMore and more prefabricated steel–concrete hybrid wind turbine towers have been built because of their better lateral stiffness than those of the full steel towers, in which epoxy resin joints are commonly adopted at the horizontal joint between two ring units for improving the erection speed. In fact, epoxy resin joints are designed in the same way as dry joints due to the very thin thickness of epoxy resin layer, in which epoxy resin only acts as a leveling blanket and sealer for jointing and compensates for the unevenness of the contact surface between two ring units. The current design method for the resistance to torsional moment at the horizontal joint is not reasonable because of the unreasonable assumption of Saint‐Venant's torsional theory. The integral expressions of the ultimate torsional moment at the horizontal joint with and without shear force are derived, respectively. The solution of the integral expressions for the ultimate torsional moment is realized by Python programming. The refined finite element analyses of two cases are compared with the existing small‐scale tests with segmental aluminum tubes, which verifies the calculation accuracy of the proposed integral method. In the modified integral model of the ultimate torsional moment, a correction term of the resistance to torsional moment and a more suitable distribution of shear stress under the action of horizontal shear force are proposed to obtain a more accurate ultimate torsional moment. Finally, 36 sets of cases with typical dimensions and axial forces in practical engineering are analyzed by the proposed integral model in the absence of horizontal shear force. One six‐parameter model for calculating the ultimate torsional moment is fitted by the least square method. A discount factor is proposed to consider the influence of the horizontal shear force on the ultimate torsional moment.

Glulam frame corner joints built of birch plywood and mechanical fasteners: An experimental, analytical, and numerical study

This study investigates frame corner joints built of birch plywood plates and glulam elements connected via self-tapping screws. Analytical calculations based on the fastener group’s torsional moment resistance, the proposed fastener group’s elastic and post-elastic load-bearing criteria, and the design formulas in Eurocode 5 were performed to predict the connection capacity in both elastic and post-elastic stages. A combined action check formula was adopted to predict the capacity of birch plywood plates and glulam elements. Frame corner specimens constructed with three different plywood thicknesses were planned to study the influence on global behavior and rotational stiffness. The specimens were intentionally designed so that failure occurred either in plywood or in glulam, in order to examine the robustness and validity of analytical calculation models. Another supplementary test group with 21 mm plywood and fewer fasteners was also designed and tested, in which the plastic yield of fasteners was expected. The test results of this supplementary group served to calibrate the analytical model that predicts the elastic and post-elastic capacity of the connection group. As a result of the comparison, the analytical calculations gave reasonable predictions on the failure of plywood, glulam, and the capacity of the fastener group. Only when the exposed moment exceeded the post-elastic limit of the fastener group did the plastic yielding of fasteners become observable. Moreover, numerical finite element models adopting the foundation zone-modeling scheme were constructed, which were proven to capture all test configurations' linear loading stiffness satisfactorily.

The experimental and numerical investigation of fracture behaviour in PMMA notched specimens under biaxial loading conditions – Tension with torsion

This paper presents the results of experimental fracture test of flat PMMA specimens under biaxial loading condition tension with torsion (proportional). The specimens were made in two thicknesses: 5 and 15 mm and were weakened with V-type edge notches with different root radii: 0.5; 2 and 10 mm. Thanks to the ARAMIS 3D 4 M non-contact vision system, measurement of the elongation and twist angle were recorded. During experimental part all of the deformation processes were observed using PHANTOM cameras. Obtained records made it possible to precisely indicate the moment of crack initiation (tensile force and torsional moment values). Using the microscopic observations the location of crack initiations were determined. Results obtained for biaxial loading were compared with those obtained for uniaxial tension and torsion. Based on experimental data the numerical calculation with FEM were carried out. The principal stress and plastic strain distribution under critical load, were obtained. The points of occurrence of stress maxima and plastic strain were indicated, which were taken as potential crack initiation sites. On the basis of the stress and plastic strain values measured at the critical points, a stress–strain fracture criterion was formulated, which was then positively verified. Additionally, new form of stress–strain fracture criterion was proposed. The bilinear form of the fracture criterion can be successfully used to predict fracture in PMMA flat specimens, regardless of the notch root radius, type of load or element thickness.

Omnidirectional simulation analysis of thermo-mechanical coupling mechanism in inertia friction welding of Ni-based superalloy

The coupling between heat and pressure is the kernel of inertia friction welding (IFW) and is still not fully understood. A novel 3D fully coupled finite element model based on a plastic friction pair was developed to simulate the IFW process of a Ni-based superalloy and reveal the omnidirectional thermo-mechanical coupling mechanism of the friction interface. The numerical model successfully simulated the deceleration, deformation processes, and peak torsional moments in IFW and captured the evolution of temperature, contact pressure, and stress. The simulated results were validated through measured thermal history, optical macrography, and axial shortening. The results indicated that interfacial friction heat was the primary heat source, and plastic deformation energy only accounted for 4% of the total. The increase in initial rotational speed and friction pressure elevated the peak temperature, reaching a maximum of 1525.5 K at an initial rotational speed of 2000 r/min and friction pressure of 400 MPa. The interface heat generation could form an axial temperature gradient exceeding 320 K/mm. The radial inhomogeneities of heat generation and temperature were manifested in a concentric ring distribution with maximum heat flux and temperature ranging from 2/5 to 2/3 radius. The radial inhomogeneities were caused by increasing linear velocity along the radius and an opposite distribution of contact pressure, which could reach 1.7 times the set pressure at the center. The circumferential inhomogeneity of thermo-mechanical distribution during rotary friction welding was revealed for the first time, benefiting from the 3D model. The deflection and transformation of distribution in contact pressure and Mises stress were indicators of plastic deformation and transition of quasi-steady state welding. The critical Mises stress was 0.5 times the friction pressure in this study. The presented modeling provides a reliable insight into the thermo-mechanical coupling mechanism of IFW and lays a solid foundation for predicting the microstructures and mechanical properties of inertia friction welded joints.