Torsion Of Shaft Research Articles

A new ornithopod from the Upper Cretaceous (Huincul Formation) of northwestern Patagonia, Argentina: Implications on elasmarian postcranial anatomy

The aim of the present contribution is to describe the first ornithischian species from the Huincul Formation (Cenomanian-Turonian, Upper Cretaceous) at the Pueblo Blanco Natural Reserve, Río Negro province, Argentina. The new species, named Chakisaurus nekul gen. et sp. nov., can be comfortably included among elasmarian ornithopods. The new species shows humeral anatomy that is congruent with smaller members of the clade (e.g. Anabisetia, Notohypsilophodon), and differs from larger taxa (e.g. Talenkauen, Mahuidacursor) which show humeral features probably related with graviportal habits, such as lack of shaft torsion and a distally located deltopectoral crest. This indicates that graviportal habits were probably acquired independently in elasmarians from other large-sized taxa, such as hadrosauroids. Caudal vertebrae of the new species also show a unique combination of characters shared with other elasmarians, which are absent in previously known ornithopods. These features indicate that some elasmarians had a protonic tail posture, which is unknown in other ornithischians and was previously considered unique to derived titanosaurian sauropods. The shape of transverse processes and neural spines of caudal vertebrae indicate that at least some elasmarians had improved cursorial habilities, that were convergently acquired by selected theropod clades.

Distal femoral torsion is correlated with higher-grade trochlear dysplasia and shorter anterior condyles in patients with patellar dislocation and increased femoral torsion.

To describe the characteristics of femoral torsion in patients with different segmental torsion types and to evaluate the correlations between segmental torsion and the morphology of the femoral condyles and trochlea in patients with patellar dislocation and increased femoral torsion. Between January 2021 and March 2023, 69 patients were included and classified into two groups according to the femoral segment contributing the most to total torsion: 32 patients in Group A (femoral neck and shaft torsion) and 37 patients in Group B (distal torsion). Trochlear dysplasia was evaluated using Dejour's classification and sulcus angle. The morphology of the femoral condyles was evaluated using the lengths and ratios of the medial and lateral condyles. Correlations between femoral torsion and morphology were evaluated. Total torsion was significantly correlated with femoral neck and shaft torsion (r = 0.882, P < 0.001) and distal torsion (r = 0.262, P = 0.030). Femoral neck and shaft torsion was significantly increased with increasing total torsion. The trochlear sulcus was flatter and more dysplastic, and the anterior condyles were shorter in Group B. Distal torsion was significantly correlated with the lengths of the medial and lateral anterior condyles (r = - 0.567, P < 0.001; r = -0.701, P < 0.001), sulcus angle (r = 0.611, P < 0.001) and Dejour trochlea type (r = 0.512, P = 0.001), while femoral neck and shaft torsion showed no correlations. Femoral torsion is a complex of femoral neck and shaft torsion and distal torsion, especially femoral neck and shaft torsion. Distal torsion was significantly correlated with a flatter trochlear sulcus, higher-grade trochlear dysplasia, and shorter anterior condyles. The new findings highlighted the importance of the segmental evaluation of femoral torsion, which would facilitate understanding of the anatomical characteristics of femoral torsion in patients with patellar dislocation and increased femoral torsion and may lead to improvement in the surgical options regarding femoral torsion. Level III.

Torsion of the Truncated Hollow Orthotropic Elastic Body of Rotation

This paper deals with the torsion of the body of rotation. The meridian section of the body is bounded by two ellipses and two straight lines which are perpendicular to the axis of rotation of the body. The material of the body is elastic and cylindrical orthotropic. To solve the torsion problem, the theory of the torsion of shafts of varying circular cross-sections is used, which was developed by Mitchell and Töppl. An analytical solution is given for the shearing stresses and circumferential displacement. A numerical example illustrates the application of the presented analytical solution. The results of this paper can be used as a benchmark solution to verify the accuracy of the results computed by finite element simulations and finite different methods.

Modal characteristics of a flexible dual-rotor coupling system with blade crack

Rotating blade is highly susceptible to cracking in harsh conditions, which seriously affects the dynamic characteristics of the power equipment. Existing research focuses primarily on the blade crack in a single blade or bladed disk, ignoring the flexibility and coupling factors of the shaft. This paper aims to present a theoretical framework for modeling a whole flexible dual-rotor system and investigate the effects of blade crack on the modal characteristics of the coupling system. The finite element and assumed modes (FE-AM) hybrid method is adopted to model the dual-rotor system. The crack-caused stiffness loss is determined based on the released strain energy. The accuracy of the developed model is verified by comparing it with the finite model and experimental results. After that, the influences of the rotating speed and crack parameters on the coupling system are systematically investigated. The results indicate that frequency veering and mode shift occur with increasing rotating speed due to the rotational effects affecting each flexible component differently. Blade bending and shaft torsion are coupled, and each affects the mode predominated by the other. The blade crack causes mode localization and mistuned distribution phenomenon in the disk. The shaft’s bending and torsion modes are coupled into the coupling modes associated with blade bending due to the blade crack as well. It is also demonstrated that the crack-caused disk’s localized mode is gradually transformed from the 2-nodal diameter mode. Furthermore, the natural frequencies associated with the disk’s low-nodal diameter and the mode shapes associated with the high-nodal diameter are sensitive to the blade crack. The proposed model can provide a theoretical foundation for fault diagnosis of blade crack in the rotating machine.

Detection of Torque Security Problems Based on the Torsion of Side Shafts in Electrified Vehicles

In the case of electric vehicle drives, faults in the drive system or in the traction inverter, which controls the vehicle drive unit, could lead to abrupt and unpredictable motion as well as acceleration of the vehicle. In terms of functional safety, the typically existing, permanent mechanical connection of the drive machine with the drive wheels poses a high safety risk. In particular, unintended motion of the vehicle from a standstill is especially critical due to the high risk of injury to traffic participants. To reduce this risk, appropriate monitoring algorithms can be applied for the rapid detection of faulty operation. A corresponding algorithm for fault detection in the electric drive of a vehicle is presented in this paper. In addition to the description of the algorithms, various driving maneuvers of an electric single-wheel drivetrain are simulated in fault-free and faulty operation on a hardware-in-the-loop test bench. The focus here is on the consideration of driving-off operations.

Geometric variation of the human tibia-fibula: a public dataset of tibia-fibula surface meshes and statistical shape model.

Variation in tibia geometry is a risk factor for tibial stress fractures. Geometric variability in bones is often quantified using statistical shape modelling. Statistical shape models (SSM) offer a method to assess three-dimensional variation of structures and identify the source of variation. Although SSM have been used widely to assess long bones, there is limited open-source datasets of this kind. Overall, the creation of SSM can be an expensive process, that requires advanced skills. A publicly available tibia shape model would be beneficial as it enables researchers to improve skills. Further, it could benefit health, sport and medicine with the potential to assess geometries suitable for medical equipment, and aid in clinical diagnosis. This study aimed to: (i) quantify tibial geometry using a SSM; and (ii) provide the SSM and associated code as an open-source dataset. Lower limb computed tomography (CT) scans from the right tibia-fibula of 30 cadavers (male n = 20, female n = 10) were obtained from the New Mexico Decedent Image Database. Tibias were segmented and reconstructed into both cortical and trabecular sections. Fibulas were segmented as a singular surface. The segmented bones were used to develop three SSM of the: (i) tibia; (ii) tibia-fibula; and (iii) cortical-trabecular. Principal component analysis was applied to obtain the three SSM, with the principal components that explained 95% of geometric variation retained. Overall size was the main source of variation in all three models accounting for 90.31%, 84.24% and 85.06%. Other sources of geometric variation in the tibia surface models included overall and midshaft thickness; prominence and size of the condyle plateau, tibial tuberosity, and anterior crest; and axial torsion of the tibial shaft. Further variations in the tibia-fibula model included midshaft thickness of the fibula; fibula head position relative to the tibia; tibia and fibula anterior-posterior curvature; fibula posterior curvature; tibia plateau rotation; and interosseous width. The main sources of variation in the cortical-trabecular model other than general size included variation in the medulla cavity diameter; cortical thickness; anterior-posterior shaft curvature; and the volume of trabecular bone in the proximal and distal ends of the bone. Variations that could increase the risk of tibial stress injury were observed, these included general tibial thickness, midshaft thickness, tibial length and medulla cavity diameter (indicative of cortical thickness). Further research is needed to better understand the effect of these tibial-fibula shape characteristics on tibial stress and injury risk. This SSM, the associated code, and three use examples for the SSM have been provided in an open-source dataset. The developed tibial surface models and statistical shape model will be made available for use at: https://simtk.org/projects/ssm_tibia.

Analysis of Torsional Vibration of Diesel Shaft System using Hard Coupling with Working Machine

The model is built to analyze and calculate the torsional vibration of the internal combustion engine shaft system and the generator connected by hard coupling to assess the response to the free and forced vibration of the shaft system, thereby serving as a basis for devising a suitable plan to reduce or avoid the problem of shaft torsion vibration. The results of the research include: modeling and building a separate calculation program for shaft torsion vibrations using MATLAB software; free vibration response analysis including calculating the vibration mode frequency and corresponding vibration forms; analyzing the forced vibration response including the amplitude of vibration of the degrees of freedom and the torsion stress of each element.

Load Distribution and Dynamic Response in Torque Split Applications

This study consists of constructing and analyzing gear mathematical models of torque split systems for contact pressure distribution and dynamic transmission error at different gear positions concerning phase angles. According to the method specified in the AGMA 927 standard, load distribution is calculated by considering shaft torsion and bending deformations. Partial contact loss may occur as a result of shaft bending with asymmetric gear positioning on a long shaft. The contact separation can be decreased by reaction force balancing if the driven gears are in the opposite position with respect to the drive gear. In the calculation of the dynamic transmission error of the torque split model, a parametric phase difference for the gear positions is proposed using gear geometry parameters. The variation of the dynamic response according to the change in the parametric phase angle in the torque split system is analyzed for the same values of each gear. Small changes in the phase values change the system response significantly. To obtain lower dynamic transmission error amplitude, the phase difference and gear positions are examined. The contact pressure distribution is validated by the finite element method, and the dynamic transmission error is compared with the experimental study in the literature.

Analytical interpretation and numerical simulation on the dynamic coupling of a flexible cyclic blades-disk-shaft system

This paper focuses on the influence mechanism of cyclic blades on the dynamic coupling of a flexible shaft-disk-blade (FSDB) system through mathematical analysis and numerical simulation. Firstly, a coupling mechanism model of an FSDB unit is developed through a Lagrange method and the assumed mode method (AMM), after considering the coupling behavior among shaft bending, shaft torsion, disk vibration, and blade bending. The modal comparison results between the proposed model and FEM affirm the validity of the model. Then the analytical interpretation is explored by decomposing and discussing the diagonal coupling and cross-coupling matrices of the FSDB system. The mechanism discussion reveals that the coupling matrices originate from the rigid and elastic motions of flexible disk and cyclic blades, indicating that the motions of cyclic blades play an important role in dynamic coupling. Therefore, the motions of cyclic blades are classified and analyzed, and their effects on natural frequencies (NFs) and critical speeds (CSs) are applied to further interpret and validate the dynamic coupling through numerical simulation. The numerical results indicate that motions of cyclic blades can increase, decrease, and eliminate the magnitude of dynamic coupling significantly.

전력계통 저주파수 진동억제를 위한 회전형 변압기 속도제어에 관한 연구

Recently, an energy transition is taking place around the world in the direction of increasing the proportion of renewable energy in order to reduce carbon emission. Accordingly, the problem of unbalanced distribution of power resources and loads has been raised, and the studies on asynchronous grid connection and AC-DC hybrid grid connection based on long distance large capacity power transmission technologies such as HVDC and HVAC are in the spotlight. Such a complex system structure may threaten the stability of the system so consideration of system operation is essential. In particular, Low Frequency Oscillation (LFO) is considered to be a factor that adversely affects power system stability, such as a torsion of a generator shaft or a decrease in generator output. LFO occurring under certain conditions in the power system are characterized by slow attenuation or gradually amplification. As a solution to suppress such LFO, there are PSS (Power System Stabilizer) of a generator system, FLC (Frequency Limit Control) of DC power system, and FACTs (Flexible AC Transmission system) facilities. However, these conventional studies have problems such as control difficulties and high investment costs. In this paper, a LFO suppression method using Variable Frequency.

On the restrained torsional warping of thin‐walled elastic shafts

AbstractThis paper studies the torsion of thin‐walled shafts when warping is restrained. It focuses on the treatment of the warping–twist constraint (whereby the twisting of the shaft is constrained to control the warping of its cross sections) by different formulations of warping torsion. This constraint underlies the kinematics of the classical TWKV formulation of Timoshenko‐Wagner‐Kappus‐Vlasov, whereas it is relaxed in the widely‐used RBV formulation of Reissner‐Benscoter‐Vlasov and the new mixed formulation recently proposed by the author. These two unconstrained formulations are still able to enforce the constraint in a penalty‐type limit process depending on specific combinations of the section's torsional constants, some new to the literature. Here we obtain rigorous estimates of these torsional constants and penalty parameters in the thin‐wall limit, thus providing an alternative understanding of the physical response of these sections. In particular, we prove that the constrained limit is attained in the thin‐wall limit for open sections but not for closed (multiply‐connected) cross sections. These analyses also provide an understanding of how those three formulations model the torsion of elastic shafts. To this purpose, we also undertake a detailed numerical evaluation of these considerations. The results presented here show the improved performance gained by the new mixed formulation of warping torsion, avoiding the anomalies observed for the TWKV formulation and the incorrect (not in equilibrium) RBV stresses.

A physics-, SCADA-based remaining useful life calculation approach for wind turbine drivetrains

This paper describes the development of a physics-, SCADA-based model able to predict the expected lifetime for wind turbine drivetrains. A real-time coupled torsional gearbox-generator model is developed using the bond graph approach in the software 20SIM. The model uses SCADA data with a sampling frequency of one hertz to impose a load reference on the wind turbine for the simulation model. From the SCADA measurements, rotor torque is estimated and used as input load to the wind turbine rotor, while generator speed is used as reference in the control loop for maximum power point tracking. Shaft torsion is used to predict highspeed shaft radial and axial bearing loads from static equilibrium. The load amplitude and the number of stress cycles are calculated using the load duration distribution method and damage is calculated using Miner’s rule. Expected lifetime is predicted by linear extrapolation of the accumulated fatigue damage to the fatigue limit. Results show that the model can capture the torsional and electrical dynamics and that the model results agree with the reference input. The radial bearing loads match well with literature where additional sensors are used to determine the loads.

Aeroservoelastic stability of a floating wind turbine

The problem of negative damping undermines the aeroservoelastic stability of floating offshore wind turbines. The negative damping problem is most prevalent around rated wind speed, where the sensitivity of thrust to wind speed is the largest. This paper investigates the implementation of peak shaving, a controller feature that limits the rated thrust by pitching the blades before rated wind speed is reached. Two controller designs are investigated: a de-tuned controller and a nacelle-feedback controller. A time-domain metric is defined, inspired by Lyapunov theory, in order to compute and assess the stability of floating offshore wind turbines. The model of the International Energy Agency 15-MW reference wind turbine mounted on the University of Maine VolturnUS-S floater is simulated in HAWC2 with the National Renewable Energy Laboratory reference open-source controller. Peak shaving is applied to the two controller designs and stability is assessed. According to the chosen metric, peak shaving does not improve the stability of the system. This is due to the trade-off between loads and error tracking: although the loads and displacements in the fore-aft direction of the turbine are reduced, the rotor-speed tracking is poorer, which increases the shaft torsion fatigue load.

Rancang Bangun Mesin Press Karet Dari Lateks Menjadi Sheet Skala Home Industry

Abstract&#x0D; Rubber press machine is a tool used to press rubberfrom lumps into sheets or sheets that have been determined in thickness. This machine works with three pairs of rolls and after calculating the planning of the rubber press machine, the roll size is obtained: length 500 mm, Roll Diameter 76.2 mm, with 3 inch pipe iron material. Rubber press machine power 0.09628 kW, speed 0.204653 m/second. Motor power 0.17035 kW. Shaft, Diameter of shaft 20 mm, Material of shaft carbon steel, Moment of torsion of shaft 2736,7635 kg/mm2, Shaft shear stress 361,74468 kg/mm2. Frame, Frame length 150 cm, Frame height 110 cm, frame width 60 cm. Pegs, 7 mm width of the key, 30 mm of key length, 7 mm of key thickness, 4 mm of keyway depth on the shaft, Shear stress on the key, 1,303 kg/mm2, Allowable shear stress on the post 3,055 kg/mm2. Pully, pulley ratio A : 4, pulley belt speed 3.88 m/s, pully diameter 203.2 mm, pully rotation 365 rpm, shaft axis distance 320 mm. Comparison of pully B: 2.6667, speed of belt pully 1.455 m/sec, length of belt 1118,048 mm, diameter of pully 203.2 mm, rotation of pully 136.87 rpm, axle distance of 240 mm. Comparison of pully C: 2.6669, speed of pully belt 0.545 m/sec, belt length 1118,048 mm, pully diameter 203.2 mm, pully rotation 51.32 rpm, shaft axis distance 240 mm. Comparison of pulleys D and E: 1, pulley belt speed 0,545 m/sec, belt length 1318,048 mm, pully diameter 203.2 mm, pully rotation 51.32 rpm, shaft axis distance 340 mm. Bearing, Bearing number 6004, Inner diameter 20 mm, Outside diameter 42 mm, Bearing width 12 mm, Dynamic nominal capacity 735 kg, Static nominal capacity 465 kg, Axial load 51.15 kg, Radial load 170.5 kg, Dynamic equivalent load 169.6475 kg, Static equivalent radial load 196.675 kg.

Fretting fatigue of multiaxially loaded shrink-fit connections – the effect of material sensitivity on fatigue strength

An accurate method for estimating high-cycle fatigue for shaft–hub connections is desired for safe machine design. Especially in drive-train applications, different multiaxial loads act on the joined parts. The resulting multiaxial stress state near the contact edge as well as the corresponding tribological state influence the fatigue strength in high-cycle fatigue regime. Investigating different load parameters, staircase fatigue experiments were performed under conditions of combined rotating bending and dynamic torsion of shrink-fitted shaft–hub connections with pairings of like materials. The comparison of normalized C45+N steel with quenched and tempered 42CrMo4+QT steel in particular revealed a difference in sensitivity to tribological stress. Where material strength is greater, greater loads lead to greater relative motion between shaft and hub, as well as more variation in contact pressure due to bending. This greater tribological stress leads to more extensive surface degradation and crack initiation occurs at lower loads compared to the higher material strength. To consider these effects in the fatigue calculation, integral fatigue criteria are used to determine the critical distance where the equivalent stress should be evaluated (Fig. 1). Due to crack-closing compressive loads caused by the contact pressure, greater critical distances (point method) were determined than are known for free surface cracks in the literature using the finite element method. The empirically determined material sensitivity could not be reproduced by adaptating the critical distance for the quenched and tempered steel.

Dynamics of Electromechanical Systems Containing Long Elastic Couplings and Safety of Their Operation

The electromechanical systems under analysis include electric drives, working machines that perform specific tasks in the technological process, and working mechanisms that transmit mechanical power between the electric drive and the working machine. The vast majority of electric motors included in drive systems require rotational speed control. This task is most often performed with the use of closed-loop control structures based on speed controllers. A step or overly rapid change in the speed reference causes a temporary lock of the speed controller due to the applied limitations at its output. Particularly, unfavorable effects of such a lock can be observed in drive systems in which there is a long elastic coupling (transmission shaft) between the electric motor and the working machine. As a consequence, shaft torsion and accompanying twisting moments of considerable amplitudes appear. This article proposes an uncomplicated active torque limiter structure, which enables the uninterrupted operation of the speed controller thanks to the automatic adaptation of the rate of the speed reference change to any moment of inertia of the rotor and attached rotating masses. The results of the investigations confirm the effectiveness of the proposed structure.

Determination of material properties of a linearly elastic peridynamic material

We investigate the properties of an isotropic linear elastic peridynamic material in the context of a three-dimensional state-based peridynamic theory, which considers both length and relative angle changes, and is based on a free energy function proposed in previous work that contains four material constants. To this end, we consider a class of equilibrium problems in mechanics to show that, in interior points of the body where deformations are smooth, the corresponding solutions in classical linear elasticity are also equilibrium solutions in peridynamics. More generally, we show that the equations of equilibrium are satisfied even when two of the four peridynamic constants are arbitrary. Pure torsion of a cylindrical shaft and pure bending of a cylindrical beam are particular cases of this class of problems and are used together with a correspondence argument proposed elsewhere to determine these two constants in terms of the elasticity constants of an isotropic material from the classical linear elasticity. One of the constants has a singularity in the Poisson ratio, which needs further investigation. Two additional experiments concerning bending of cylindrical beam by terminal load and anti-plane shear of a hollow cylinder, which do not belong to the previous class of problems, are used to validate these results.

The Importance of Wake Meandering on Wind Turbine Fatigue Loads in Wake

Considering loads when optimizing wind-farm layouts or designing farm-control strategies is important, but the computational cost of using high-fidelity wake models in the loop can be prohibitively high. Using simpler models that consider only the spatial variation of turbulence statistics is a tempting alternative, but the accuracy of these models with respect to the aeroelastic response is not well understood. This paper therefore highlights the effect of replacing wake meandering with spatially varying statistics (“profile functions”) in the inflow to a downstream turbine. Profile functions at different downstream and lateral locations are extracted from a large-eddy simulation with an upstream turbine and compared with two lower-fidelity models: one that prescribes both the mean and standard deviation of the turbulence and one that prescribes only the mean. The aeroelastic response of an NREL 5 MW wind turbine is simulated with the three different wake-model fidelities, and various quantities of interest are compared. The mean values for the power and rotor speed for the medium-and low-fidelity model match well, but the accuracy of the fatigue loads varies greatly depending on the load channel. Prescribing the profile function for the standard deviation is only beneficial for the tower-base fore-aft moment; all other DELs had similar accuracies for both the medium- and low-fidelity models. The paper concludes that blade DELs can be estimated using these simple models with some accuracy, but care should be taken with the load channels related to the shaft torsion and tower-base fore-aft bending moment.

Torsion of Truncated Hollow Spherical Elastic Body

This paper deals with the torsion of a body of rotation whose shape is a truncated hollow sphere. The material of the truncated hollow sphere is isotropic, homogeneous and linearly elastic. To solve the torsion problem, the theory of torsion of shafts of varying circular cross section is used, which is introduced by Michell and Föppl. Analytical solution is given for the shearing stresses and displacements. A numerical example illustrates the application of the presented solution. The results of the presented numerical example can be used as a benchmark problem to verify the accuracy of the results computed by finite element simulations.

Dynamic coupling vibration of rotating shaft–disc–blade system — Modeling, mechanism analysis and numerical study

This study aims at revealing the coupling vibration mechanism of RSDB system. First, a comprehensive coupling dynamic model of RSDB system including the shaft bending, shaft torsion, blade bending, and blade radial deformation is formulated based on continuum beam theory and Lagrange equation. The validity of the proposed dynamic model is verified through a comparison with FEM and experimental results. Second, the general coupling mechanism of RSDB system is theoretically interpreted based on the proposed analytical coupling vibration model, which indicates that the blade vibration and shaft vibration, especially the shaft torsion vibration and blade bending vibration, may affects each other significantly. At last, the steady-state coupling vibration responses and the effects of structure parameters on the coupling vibration of RSDB system are comparatively investigated through numerical investigations. The comparative results suggest that the blade setting angle, blade–blade coupling stiffness, and the disc location on shaft will greatly affect the coupling vibrations. It worth more attention that the general coupling vibration mechanism obtained by analytical analysis and the results obtained by numerical study can be cross-verified by each other.