Torsional Moment Research Articles

Impact of shell structure stiffness on aero-structural coupling in wind turbine rotor blades

Wind turbine rotor blades are heavily loaded composite structures that experience a mixture of aerodynamic, inertial, gravitational, and gyroscopic forces during their operation life. Due to the high loads, the cross-sections of the blades are subjected to in-plane and out-of-plane deformations. The out-of-plane deformations are referred to as shear warping while the in-plane deformations are also called blade breathing. Blade breathing depends on the magnitude of the mechanical loads, which are expressed by means of internal forces and moments, and the stiffness of the blade shell.In this work, the relationships between in-plane cross-sectional deformations and internal loads are investigated. For the quantification of the deformation, a reference blade is studied via 3D finite shell element simulations for different loading scenarios. The cross-section of interest is located at the radial position of maximum chord. To compare the shape of the cross-sections in the undeformed and the deformed configurations, a procedure is proposed to relate the positions of nodes associated with the cross-section of interest in both configurations to a joint coordinate system. The shape of the deformed cross-section is then extracted and compared with the undeformed configuration. The comparison is executed for the individual internal forces and moments, namely flapwise and edgewise bending moments, normal force, shear forces, and torsion moment, respectively. The deformation patterns are discussed and it is addressed how these may influence the aerodynamic behavior of the cross-section under consideration.

Engineering Review of Wind-Induced Torsional Moment and Response of Buildings

Engineering Review of Wind-Induced Torsional Moment and Response of Buildings

Implementation of Data from Wind Tunnel Tests in the Design of a Tall Building with an Elliptic Ground Plan

The design of a 69 m tall multipurpose building was investigated in this paper. The shape of the structure above the ground was an elliptical cylinder. Under the ground, the building was extended into a cuboid shape (for car parking). External wind pressure coefficients were determined using three methods: wind tunnel tests, CFD, and “the simplification of the shape” (using information defined in building standards). From the obtained results, it was evident that the simplification did not provide results with sufficient accuracy. The external wind pressure coefficients presented in this paper should be used for the design of a similar structure. The shape of the elliptical cylinder is very sensitive to applied wind. Positive pressures only occur on a small area of the windward side. The rest of the windward side is loaded with negative pressures. Therefore, torsional effects can occur, and these can be dangerous for the structure. The leeward side is completely loaded with negative pressures. In our case, this information was necessary for a follow-on static and dynamic analysis of the building. Various subsoil stiffness coefficients were considered. The calculated horizontal displacement was compared with the limit value. A measured wind direction of 20° caused the maximum obtained torsional moment, and a wind direction of 90° induced the maximum obtained force. The commercial program Ansys Fluent 2022 was used for the CFD simulation. The SCIA ENGINEER 21 program was used for follow-on analysis. This paper presents brief information on the selected turbulence model and details the settings used for the CFD simulation. Also, a description of the wind tunnel laboratory utilized in this study is provided, along with a description of the measuring devices used and the methodologies of the tests carried out. The main purpose of this paper is to show how important it is to consider the wind load for the static analysis of a structure like this.

Biomechanical comparison of fixation methods on third-generation femoral composite bone models in Pauwels type 3 femoral neck fractures: Contribution of the medial buttress plate to fixation.

To compare the use of cannulated screws in an inverted triangular configuration, medial buttress plates, and the combination of these 2 fixation methods in the treatment of Pauwels type 3 femoral neck fractures. Twenty-eight anatomical composite third-generation femoral bone models were divided into 4 groups. The control group (group 1) was formed with 7 third-generation intact bone models. The fracture model was created with a 70° cutting block to fit 21 Pauwels type 3 fracture configurations. Seven models were fixed with an isolated 3.5 mm one-third semi-tubular medial buttress plate (group 2), 7 were fixed in an inverted triangular configuration with 6.5 mm cannulated screws (group 3), and 7 were fixed using a combination of 6.5 mm cannulated screws and a medial buttress plate (group 4). Cyclic loading was applied using axial forces ranging from 60 N to 600 N and moments ranging from 0.7 Nm to 7.0 Nm for 500 cycles. Once the cyclic loading stage was completed, the loads were removed from the system, and the quasi-static loading stage was employed to determine the stiffness and failure forces of the system under both axial and torsional forces. Quasi-static tests were performed with an axial speed of 1.8 mm/min and a torsional speed of 4.5°/min. The biomechanical properties of all groups were examined in terms of axial stiffness, torsional stiffness, and maximum axial force parameters. The stiffness values of groups 1, 2, 3, and 4 were 303 ± 35.8 N/mm, 159.6 ± 25 N/mm, 232 ± 35.9 N/mm, and 366.9 ± 58 N/mm, respectively, under axial forces (P < .01); 2172.7 ± 252.1 Nmm/°, 1225.3 ± 238.6 Nmm/°, 2123 ± 359.4 Nmm/°, and 2721.85 ± 304 Nmm/°, respectively, under torsional moments (P < .01); and 2072.1 ± 256.1 N, 1379.9 ± 290.6 N, 2099.1 ± 454.2 N, and 2648.4 ± 364.6 N, respectively, under the maximum force (P < .01). This study showed that in the fixation of Pauwels type 3 fractures formed on third-generation bone models, the utilization of half-thread cannulated screws in an inverted triangle configuration, along with a medial buttress plate, provided stronger fixation compared to the remaining implant groups and the control group. According to the evaluation of the parameters, the isolated application of a medial buttress plate had poorer biomechanical properties than other fixation methods.

Loading of the Hip and Knee During Swimming: An in Vivo Load Study.

Swimming is commonly recommended as postoperative rehabilitation following total hip arthroplasty (THA) and total knee arthroplasty (TKA). So far, in vivo hip and knee joint loads during swimming remain undescribed. In vivo hip and knee joint loads were measured in 6 patients who underwent THA and 5 patients who underwent TKA with instrumented joint implants. Joint loads, including the resultant joint contact force (F Res ), torsional moment around the femoral shaft axis or the tibial axis (M Tors ), bending moment at the middle of the femoral neck (M Bend ), torsional moment around the femoral neck axis (M Tne ), and medial force ratio (MFR) in the knee, were measured during breaststroke swimming at 0.5, 0.6, and 0.7 m/s and the breaststroke and crawl kicks at 0.5 and 1.0 m/s. The ranges of the median maximal F Res were 157% to 193% of body weight for the hip and 93% to 145% of body weight for the knee during breaststroke swimming. Greater maxima of F Res (hip and knee), M Tors (hip and knee), M Bend (hip), and M Tne (hip) were observed with higher breaststroke swimming velocities, but significance was only identified between 0.5 and 0.6 m/s in F Res (p = 0.028), M Tors (p = 0.028), and M Bend (p = 0.028) and between 0.5 and 0.7 m/s in F Res (p = 0.045) in hips. No difference was found in maximal MFR between different breaststroke swimming velocities. The maximal F Res was significantly positively correlated with the breaststroke swimming velocity (hip: r = 0.541; p < 0.05; and knee: r = 0.414; p < 0.001). The maximal F Res (hip and knee) and moments (hip) were higher in the crawl kick than in the breaststroke kick, and a significant difference was recognized in F Res Max for the hip: median, 179% versus 118% of body weight (p = 0.028) for 0.5 m/s and 166% versus 133% of body weight (p = 0.028) for 1.0 m/s. Swimming is a safe and low-impact activity, particularly recommended for patients who undergo THA or TKA. Hip and knee joint loads are greater with higher swimming velocities and can be influenced by swimming styles. Nevertheless, concrete suggestions to patients who undergo arthroplasty on swimming should involve individual considerations. Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Torsional Modeling of Reinforced Concrete Beam–Column Joint Retrofitted by Aramid Fiber—Experimental and Numerical Analysis

The performance of structural composites during loading has always been a concern for the designers and construction industry since the reinforced concrete structure was discovered. In this study, lateral load–displacement behavior of beam–column joints wrapped with aramid fiber is evaluated using both experimental and numerical analysis subjected to torsional moment (beam-eccentric loading). Three categories of reinforcement concepts are adopted for the preparation of the beam–column joints, where members are wrapped with aramid fiber at the joints, and others are not fortified with aramid fibers. Prior to testing, the structural composites are cured for maximum 28 days into water. The beam–column joints are subjected to lateral load at a point near the column end of the beam–column connection, and the corresponding deflections are measured until the member fails. Based on the test results, ductility and energy absorption capacity are evaluated. The findings of the numerical investigation of beam–column joint show there is not much variation in the experimental and numerical analysis; it is clearly found that aramid fiber wrapping provided large rigidity in the joint, and it is also prolonged the final failure of the joints. This study shows that in addition to the conventional reinforcement, providing the hanger reinforcement and the diagonal reinforcement improves the rigidity of the beam–column joints during severe loadings, as this study described.

Lower-limb internal loading and potential consequences for fracture healing.

Introduction: Mechanical loading is known to determine the course of bone fracture healing. We hypothesise that lower limb long bone loading differs with knee flexion angle during walking and frontal knee alignment, which affects fracture healing success. Materials and methods: Using our musculoskeletal in silico modelling constrained against in vivo data from patients with instrumented knee implants allowed us to assess internal loads in femur and tibia. These internal forces were associated with the clinical outcome of fracture healing in a relevant cohort of 178 extra-articular femur and tibia fractures in patients using a retrospective approach. Results: Mean peak forces differed with femoral compression (1,330-1,936N at mid-shaft) amounting to about half of tibial compression (2,299-5,224N). Mean peak bending moments in the frontal plane were greater in the femur (71-130Nm) than in the tibia (from 26 to 43Nm), each increasing proximally. Bending in the sagittal plane showed smaller mean peak bending moments in the femur (-38 to 43Nm) reaching substantially higher values in the tibia (-63 to -175Nm) with a peak proximally. Peak torsional moments had opposite directions for the femur (-13 to -40Nm) versus tibia (15-48Nm) with an increase towards the proximal end in both. Femoral fractures showed significantly lower scores in the modified Radiological Union Scale for Tibia (mRUST) at last follow-up (p < 0.001) compared to tibial fractures. Specifically, compression (r = 0.304), sagittal bending (r = 0.259), and frontal bending (r = -0.318) showed strong associations (p < 0.001) to mRUST at last follow-up. This was not the case for age, body weight, or localisation alone. Discussion: This study showed that moments in femur and tibia tend to decrease towards their distal ends. Tibial load components were influenced by knee flexion angle, especially at push-off, while static frontal alignment played a smaller role. Our results indicate that femur and tibia are loaded differently and thus require adapted fracture fixation considering load components rather than just overall load level.

Experimental Torsional Capacity of Plain Concrete Beams Made from Crushed Clay Brick and Recycled Brick Concrete as Coarse Aggregate

Concrete was made with four different types of coarse aggregate, i.e., natural stone aggregate concrete (NSAC), crushed virgin clay brick aggregate concrete (VBAC), crushed recycled brick concrete aggregate concrete (RBAC), and crushed recycled stone concrete aggregate concrete (RSAC). Beam specimens prepared from these four types of concrete were subjected to pure torsional moment up to failure. From this experimental procedure, ultimate torque at failure along with twisting angle were observed. From the torque vs. twisting angle curves, torsional stiffness and torsional toughness were also evaluated for these four types of concrete. It was observed that ultimate torque of VBAC and RBAC was 95% and 90% of that of NSAC, respectively. The torsional toughness of VBAC was found to be 68%–72% of that of NSAC. In addition, experimental torques were compared with predictions of torsional strength as per five commonly used models. For VBAC, the ultimate torque prediction made by skew bending theory was found to be the closest to the experimental findings.

Experimental investigation of rotational behavior of pseudo-ductile adhesive angle joints exhibiting variable strain rate

Pseudo-ductile behavior in composite structural frames can be achieved by enabling their beam-column joints to exhibit nonlinear structural response due to progressive damage, by using pseudo-ductile adhesives. This study investigates the static behavior of a novel pseudo-ductile bonded-bolted angle joint with a bolt at the geometric centroid of the joint. A pseudo-ductile elastomer adhesive is used which is notably sensitive to the strain rate. The bolt ensures structural integrity and produces pure torsional moments in the adhesive planes. This configuration induces nonuniform strain rates in the adhesive layers in the radial direction, i.e., from the center outwards. The experimental results reveal that under the nonuniform shear strain distribution, the initial stiffness, yield rotation, and maximum torsion exhibit an increasing trend with strain rate, while maximum rotation decreases. An analytical model was developed using stress-strain relations obtained from single-lap joints with uniform stress distribution to predict the angle joint responses. The analytical model overestimates the initial joint stiffness due to the nonuniform stress distribution but shows good agreement for strength and post-yield behavior. Lastly, the angle joint exhibits the lowest ductility ratios compared to linear lap joints, showing that the pseudo-ductile adhesive capacity may not be fully utilized in the angle configuration.

Flexural-torsional analysis of steel beam structures using ANSYS

The theories for uniform torsion and non-uniform torsion are studied. The aim of the paper is to study the behaviour of the beams of different sections for combined bending and torsion under various loadings and support conditions. The comparative study of the finite element for beams with different geometry sections of solid and hollow circular sections, rectangular section and symmetric I sections subjected to concentric and eccentric loading conditions with simply supported and cantilever end conditions is presented using ANSYS 18.1 workbench. The length of the beam is kept constant as 4 m. The transverse and axial deformation, the equivalent stresses and strains of beams were studied along with the mode of failure and effect of bending and torsion. It was observed that concentric loading resulted in transverse deflections while the torsional moment loading causes in-plane deformation in form of twisting of the cross-section with maximum stress generation and the eccentric loading results in combined transverse and in-plane axial deformation. From the result obtained it can be said that open sections has lesser efficiency for torsional and eccentric type loading as higher stresses and axial deflections were observed as compared to the hollow circular and rectangular sections.

Flexural–torsional vibration of thin-walled beams with open cross sections considering the additional torsional moment

Flexural–torsional vibration of thin-walled beams with open cross sections considering the additional torsional moment

Safety and environmental impact control of cross passage construction in soft soil strata using tunnel boring machine method

The construction of cross passages using the tunnel boring machine (TBM) method represents an emerging construction technique with numerous advantages. However, owing to the scarcity of application instances, the safety control methodologies and the regulatory patterns concerning environmental impacts remain inconclusive. In this study, a cross passage excavated using the TBM method—the first of its kind in the Tianjin area—was investigated. We identified the key risk control measures for the construction and analysed the TBM operating parameters, monitored ground and building settlements, and monitored mainline tunnel deformations and mechanical responses, revealing the ground and tunnel structure deformation patterns. The following conclusions are drawn. (1) The ground surrounding the cross-passage break-out opening was stabilised by performing secondary grouting and small-range freezing, and the break-in opening was excavated using a completely enclosed steel sleeve. These measures prevented water and sand inflows during the excavation of the break-out and break-in openings in the silt and silty sand strata. (2) The torsional moment of the cutter disc was large during the break-out phase. Break-out mainline tunnel displacement monitoring data indicated that the thrust had a significant effect on the mainline tunnel during the break-out phase. (3) The TBM tunnelling caused ground loss. The ground settlement exhibited a U-shaped distribution along the cross-passage axis, with the maximum settlement being 10 mm. (4) During the break-out phase, the deformation of the break-out mainline tunnel exhibited a duck-egg-shaped distribution. The clearance convergence of the break-out mainline tunnel was within ± 4, and the clearance convergence of the break-in mainline tunnel was controlled within ± 1 mm.

Effectiveness of flange plates on torsional behaviors of ultra-high-performance fiber-reinforced concrete hollow beams

This study investigates the effectiveness of flanges with various types of stirrup and cross-sectional dimensions on the torsional behaviors of ultra-high-performance fiber-reinforced concrete (UHPFRC) hollow beams. A finite element model was developed and validated for simulating the torsional behavior. The impact of the essential parameters of flanges was investigated through experimental and numerical methodologies. The results showed that the inclusion of flanges substantially influenced the torsional strength of UHPFRC hollow beams, attributed to the section torsional plastic resistance moment and UHPFRC tensile capacity in flanges. The effectiveness of flange plates was considerably influenced by the web wall thickness. The stirrup type and the increase in flange reinforcement ratio, flange width, and thickness had a favorable effect on the torsional behaviors of thick-walled UHPFRC beams but minimal effect on thin-walled UHPFRC beams. The failure of thin-walled beams was determined by the web thickness and web reinforcements.

Algorithm for the plastic analysis of arbitrary steel cross sections based on finite element formulations

AbstractIn structural engineering verifications, the plastic capacity of steel members may be utilized for cross sections of class 1 and 2. In literature, algorithms for the primary torsional capacity considering different types of numerical procedures, such as finite element methods, have mainly been addressed. However, there is a lack of explicit illustration of algorithms for cross sections considering combined loading, i.e. procedures for bending and torsional analysis. This paper therefore presents an algorithm for the plastic analysis connected to a cross‐sectional finite element approach. The algorithm considers the description of bilinear material laws, accounting for ideal‐plastic behavior as well as effects of isotropic hardening. Cross sections are discretized by isoparametric two‐dimensional nine‐node elements with curvilinear boundaries, which allow describing any geometry with high accuracy. The study proves that the plastic algorithm combined with the isoparametric elements accurately represents the behavior of cross sections. In addition, precise cross‐sectional capacities of hot‐rolled U‐sections gained by the methodology, i.e. plastic torsional moments and plastic bending moments, are presented. In future research, this methodology will be combined with finite element formulations for beams.

Lateral torsional buckling of hot rolled channel sections – Numerical simulations and design proposal

AbstractThis paper describes a parametric study addressing the resistance of U‐profiles (channel profiles) subject to bending and torsion to lateral torsional buckling. In case of U‐sections, the torsional moment results, in the majority of cases, from an unavoidable eccentricity of the applied load from the shear centre. The behavior and resistance of the studied members is addressed through a parametric study based on a numerical model validated with laboratory tests. This study is divided into two parts. First, U‐sections subject to bending only are studied in order to provide a method for this reference load case. In particular, the non symmetric stability behaviour of this type of section will be highlighted. Based on the numerical results an adaption of the European buckling curves is proposed. Then, the members are studied under combined bending and torsion. Existing design methods applicable to I sections are extended in order to account for the specific behaviour of U sections.

Unexpected flange crippling of a newly built cyclist bridge

AbstractEncouragement of cycling is an effective way to reduce energy consumption by traffic. Cycling lanes will, to the greatest extent practicable, be built close to currently used traffic roads in order to establish new, swift lanes that require little space. Building near railroads appears acceptable for the latter, preferably by cantilevered structures atop existing bridges. In the event that this is not acceptable, separate bicycle bridges may be constructed next to the railroad bridges. On the Brussels Ring Highway, close to the Zaventem Airport, the latter was the situation. The oblique bearing points at the extremities of the straight‐ended sections, used to construct this bicycle bridge experienced torsional moments during installation. This resulted in distinct folds in the bottom flange of the closed cross‐section of one of the six bridge decks. Both global FE‐models and more detailed models were created to explain this. None could adequately account for the observed flange crippling. The crippling can only be explained by an unintentionally increased torsion, which may have occurred during the manipulation of the bridge's component elements. Additional thin metal strips have been added to this section of the bicycle bridge to restore its bearing capacity.

Investigation on the Aerodynamic Parameters of the Triangle Shape of Tall Buildings by Using of CFD Method

Wind loading in large buildings has always been a major challenge for civilian engineers. For this purpose, presenting the optimum exterior forms of a building exposed to the wind flow and analyzing aerodynamic forces, including resistance force, bending, and twisting moments, are challenging issues for designers. Nowadays, by combining various numerical calculation methods, like neural networks, genetic algorithms, and other methods, by changing some parameters, they optimize the external form of the building based on aerodynamic parameters. In this research, three optimized triangular models will be investigated using the computational fluid dynamics method. For wind flow, a velocity profile is used in the three simulations, and Reynolds’ Navier–Stokes average equations are used to solve momentum relationships. Additionally, the κ-ε method was used to calculate Reynolds stresses. The results show that the optimized N3 model is in the most optimal condition possible in terms of aerodynamic parameters such as drag, torsion moment, and vortices behind the building. Nowadays, the neural network algorithm is one of the most famous numerical methods for optimizing hull shapes. However, this approach cannot improve aerodynamic parameters either. Hence, computational fluid dynamics is used to deeply analyze. This research is one step forward to assess the optimized hull shapes of tall buildings. All tests are conducted using STAR CCM+.

Effect of the integral length scales of turbulent inflows on wind turbine loads

As wind turbines become larger, the fluctuations in the inflow become increasingly influential in the turbine structural loading. These fluctuations are characterized by the integral length scale, which represents the average size of the largest energy-containing turbulent eddies. Current design standards neglect the varying integral length scales that characterize inflows of wind turbines in operation. Using large-eddy simulations, we generate turbulent inflows of varying integral length scales and quantify the loads of the IEA 15-MW reference wind turbine. Results illustrate that the impact of turbulence on rotor and tower loads is up to 10 times greater than the impact of the mean shear profile. Increasing integral length scales from 0.3x to 0.5x the rotor diameter reduces blade root flapwise moments and rotor and tower loads. Increasing integral length scales from 0.5x to 1.7x the rotor diameter increases the rotor aerodynamic thrust force and the blade root flapwise shear loads and decreases the tower base torsional moment and the tilting and yawing rotor aerodynamic moments. Additionally, turbulence intensity has a greater impact on wind turbine loads than integral length scales. Findings indicate that design standards should consider varying integral length scales for accurate wind turbine loading characterization in turbulent inflow conditions.

Creep-Fatigue Life Property of P91 Welded Piping Subjected to Bending and Torsional Moments at High Temperature

Abstract In recent years, the role of thermal power plants has shifted from providing a baseload to providing supplemental supply to compensate for fluctuations in the output of renewable energy sources. Thus, the operation of these plants involves frequent startup and shutdown cycles, which lead to extensive damage caused by creep and fatigue interactions. In addition, the piping utilized in thermal plants is subjected to a combined stress state composed of bending and torsional moments. In this study, a high-temperature fatigue testing machine capable of generating such a bending-torsional loading was developed. Creep-fatigue tests were conducted on P91 steel piping with weldment. The results clarified that the creep-fatigue life was reduced by the superposition of the torsional and bending moments and that it was further reduced by a holding load. It was shown that the creep-fatigue life of piping with weldment can be estimated accurately using the equivalent bending moment, which is composed of the torsional and bending moments. It was also confirmed that crack occurred in the heat-affected zone (HAZ) of the welded part, which has been often observed in actual thermal power equipment. From the finite element analysis, it was identified that cracking was initiated in the HAZ due to the accumulation of creep strain and increase in the hydrostatic pressure component during a holding load.

Damage identification in steel plate structures considering bending and torsion moments using estimated seismic responses

This paper proposes a model-free damage identification method and suggests an effective index for damage diagnosis in steel plate-like structures considering both the torsion and bending moments using only acceleration data, with no need for geometric characteristics. The basis for damage detection is the difference between healthy and damaged structural responses to different ground accelerations. In doing so, two Peak Ground Acceleration (PGA) scales, 0.05 (g), and 0.5 (g), labeled for the Loma Prieta ground motion, are considered. Four-node meshes are applied to reflect the torsion moments in the steel plate behavior. A multi-objective function, Fisher Information Matrix, is utilized, and four sensor locations are optimized to identify the locations most sensitive to damage. AutoRegressive Moving Average with exogenous input (ARMAX) system identification method is employed to obtain the structural displacement from the acceleration data and, subsequently, the displacement state equations of the nodes. With the aid of the structural displacement and its derivatives obtained through the central finite difference approximation method, damage to the plate structure is detected at PGA = 0.05 (g) and PGA = 0.50 (g) considering thickness changes based on the peak values manifested in the proposed damage detection index. Furthermore, the recorded structural acceleration responses at the desired scales of PGAs are fed into the 2D wavelet transform to detect damage imposed on the plate structure using the diagonal component of the wavelet transform. The results confirm that the proposed nonmodel-based approach successfully detects the single and multiple damage scenarios and can be used for a quick and judicious assessment of the steel plate behavior immediately after damage.