Torsional Analysis Research Articles

Derotational distal femoral osteotomy yields better outcomes in patellar subluxation with proximal femoral torsion compared with distal femoral torsion: A retrospective comparative study.

Controversy exists regarding the origin of femoral torsion, and specific treatment rules regarding the optimal position of femoral osteotomy in patients with recurrent patellar subluxation and excessive femoral torsion are scarce. To establish a novel classification system for such patients, and to compare clinical and radiological outcomes after distal derotational femoral osteotomy (DDFO) between femoral torsion at proximal (neck and shaft) and distal levels. Between January 2014 and June 2019, patients who underwent DDFO were retrospectively reviewed. The segmental torsion analysis was performed to establish a novel classification system, and classify included patients into two groups: 35 patients in proximal torsion group and 38 patients in distal torsion group. These patients were followed-up for at least 3years. Clinical evaluations included functional outcomes, physical examinations, quality of life, activity level, satisfaction, and complications. Radiological outcomes included patellofemoral osteoarthritis, congruence, and alignment. Type I was defined as the proximal torsion. Type II was defined as the distal torsion. Proximal torsion group had lower postoperative femoral torsion (12.6 ± 2.6° vs. 14.8 ± 3.6°; P = .004) and higher surgical correction angle (21.6 ± 5.0° vs. 19.1 ± 3.0°; P = .009). All clinical and radiological outcomes improved significantly in both groups, but proximal torsion group had significantly higher quality of life (EQ-5D-5L: 0.96 ± 0.06 vs. 0.91 ± 0.07; P = .003. 92.0 ± 6.0 vs. 88.7 ± 5.8; P = .021) and Tegner activity score (5.2 ± 1.5 vs. 4.5 ± 1.4; P = .040), and fewer patellofemoral osteoarthritis (8.6% vs. 26.3%; P = .048). Two patients in the distal torsion group had subjective patellar instability. The percentage of patients with anterior knee pain was higher in the distal torsion group. A novel classification system for patients with recurrent patellar subluxation and excessive femoral torsion based on segmental femoral torsion analysis was established. DDFO was more appropriate for patients with proximal torsion, yielding higher surgical correction angle, and better clinical and radiological outcomes. Cohort study; Level of evidence, 3.

Torsion Analysis of Functionally Graded Iso/Orthotropic Sections Using Differential Quadrature and pb2-Rayleigh Ritz Methods

Torsion Analysis of Functionally Graded Iso/Orthotropic Sections Using Differential Quadrature and pb2-Rayleigh Ritz Methods

Dynamic Characteristics Analysis of the DI-SO Cylindrical Spur Gear System Based on Meshing Conditions

The dual-input single-output (DI-SO) cylindrical spur gear system possesses advantages such as high load-carrying capacity, precise transmission, and low energy loss. It is increasingly becoming a core component of power transmission systems in maritime vessels, aerospace, marine engineering, and construction machinery. In practical operation, the stability of the DI-SO cylindrical spur gear system is influenced by complex excitations. These excitations lead to nonlinear vibration, meshing instability, and noise, which affect the performance and reliability of the entire equipment. Hence, the dynamic performance of the DI-SO cylindrical spur gear system is thoroughly investigated in this research. The impact of excitations and nonlinear factors on the dynamic characteristics was investigated comprehensively. A comparative analysis of the gear system was conducted by establishing a bending–torsional coupling vibration analysis model under synchronous and asynchronous meshing conditions. Nonlinear factors such as periodic time-varying meshing stiffness, meshing damping, friction coefficient, friction arms, load sharing ratio, comprehensive transmission error, and backlash were considered in the proposed model. Then, the effect laws of excitations and nonlinear factors such as meshing frequency, driving load fluctuation, backlash, and comprehensive transmission error were analyzed. The results indicate that the dynamic characteristics exhibited staged stable and unstable states under different meshing frequencies and meshing conditions. At the medium-frequency meshing stage (0.96 × 104~1.78 × 104 Hz), alternating phenomena of multi-periodic, quasi-periodic, and chaotic motion states were observed. Moreover, the root mean square value (RMS) of the dynamic transmission error (DTE) in the asynchronized gear system was generally higher than that in the synchronized gear system. It was found that selecting the appropriate meshing condition could effectively reduce the amplitude of the DTE. Additionally, the dynamic performance could be significantly improved by adjusting control parameters such as driving load fluctuation (0~179 N), backlash (0.8 × 10−4~0.9 × 10−4 m), and comprehensive transmission error (7.9 × 10−4~9.4 × 10−4 m). The research results provide a theoretical guidance for the design and optimization of the DI-SO cylindrical spur gear system.

Torsional vibration analysis and fuzzy adaptive PID control optimization of underwater vector propulsion shaft systems

To examine the torsional vibration of vector propulsion shaft system (VPSS), a four-degree-of-freedom vibration model of the VPSS is established by concentrated mass approach, and the torsional vibration differential equation of the VPSS is deduced based on the Lagrange approach. The vibration differential equations is addressed numerically applying the Runge-Kutta algorithm to investigate the effect of various working shaft angles β on the free and forced vibration of the VPSS under the excitation conditions. To further reduce the torsional vibration amplitude and avoid fatigue damage of the system, and considering the nonlinear relationship within the system, this study develops a fuzzy adaptive PID approach to control the VPSS. The results show that the maximum torsional vibration amplitude of the VPSS is reduced by more than 70% and the transient response time is shortened by more than 90% with this control approach, which effectively reduces the torsional vibration amplitude of the VPSS and thereby significantly improves the safety performance of the underwater vehicle. This may provide technical references for the vibration control theory of the VPSS as well as engineering applications.

Torsional Vibration Analysis and Suppression of Interior Permanent Magnet Synchronous Motor With Staggered Segmented Rotor for Electric Vehicles

Torsional Vibration Analysis and Suppression of Interior Permanent Magnet Synchronous Motor With Staggered Segmented Rotor for Electric Vehicles

Torsional Vibration Analysis and Optimization Design of the Surface PM Synchronous Machine With Reduced Torque Ripple

Torsional Vibration Analysis and Optimization Design of the Surface PM Synchronous Machine With Reduced Torque Ripple

A new finite element formulation for the lateral torsional buckling analyses of orthotropic FRP-externally bonded steel beams

Abstract The present study develops a new finite element (FE) formulation for the lateral torsional buckling (LTB) analyses of steel beams exteriorly bonded with orthotropic fiber-reinforced polymer (FRP) layers. The formulation considers shear deformations, partial material interaction, local and global warping deformations, and orthotropic FRP properties. The buckling responses of multispan FRP-bonded steel beams predicted by the present solutions are excellently validated against experiment and numerical solutions. As observed, the FRP strengthening is highly effective for the LTB resistance of steel beams. However, the LTB responses are strongly dependent on the orthotropic properties and strengthening lengths of FRP layers. The effects of shear deformations, span ratios, and loading conditions on the LTB responses are also quantified in the present study.

Pure distortion of symmetric box beams with hinged walls

This paper is concerned with the analysis of the pure torsion and distortion of straight box beams with trapezial cross-sections and hinged walls. A one-dimensional mechanical model for this kind of system subjected to anti-symmetric loads on the end cross-sections and no warping constraints is developed. The distortional stiffness of the system is provided by the torsional rigidity of the wall panels. The cross-sectional kinematic condition for which torsion and distortion are uncoupled has been determined. Novel explicit expressions of the internal and external distortional moments, the distortion constant, and the distortional warping pattern have been deduced; they can be directly translated to the classical distortion theory. Results of representative test cases with different section shapes and loads show excellent agreement with finite element models using shell elements. The model is a first step to analyse bridge decks with a distortionable central cell for wind engineering applications. Finally, an extension of the model, including the distortional stiffness provided by the frame bending stiffness of the cross-section walls, is presented. The extended model is applicable to assess the large-scale torsional–distortional effects in long beams with closed cross sections.

Research on engine dynamic torque modeling for torsional vibration analysis of vehicle powertrain

In order to improve the accuracy of dynamic torque model of engine, a simulation model of quasi-transient engine dynamic torque under all operating conditions was established considering the influence of throttle opening. Firstly, the calculation model of engine output torque and cylinder pressure is established according to the kinematic relation of crank linkage mechanism. Secondly, BP neural network is used to establish the mapping relationship model of throttle opening, rotational speed, and cylinder pressure ratio data. In order to solve the contradiction between calculation accuracy and efficiency of engine cylinder pressure interpolation, a quadratic interpolation method is proposed, which refines data to improve interpolation accuracy, and improves calculation efficiency by online adjacent interpolation, and completes the construction of dynamic torque simulation model of engine in all working conditions. Finally, the experimental data of dynamic torque characteristics of the engine at different speeds are used to verify the accuracy of the model calculation. By using the verified engine model, the dynamic operating characteristics of variable valve opening and variable speed are simulated and analyzed. The results show that the model established in this paper can effectively reflect the dynamic characteristics of the engine, and the model is suitable for the simulation of the torsional vibration of the vehicle powertrain under steady and unsteady conditions.

Effect of AVL-based time-domain analysis on torsional vibration of engine shafting

The torsional vibration of the shaft system in hybrid car engines has a significant impact on the overall performance of the vehicle, and it is more complex in hybrid cars compared to traditional cars. Traditional methods for torsional vibration analysis of shaft systems have significant limitations and cannot handle nonlinear and transient problems. To explore the torsional vibration characteristics of hybrid vehicle shaft systems, a simplified engine shaft system torsional vibration equivalent model is innovatively constructed. In addition, a method for quickly determining the confidence level of the torsional vibration equivalent model is proposed. Additionally, the transient dynamic characteristics of a multi-body dynamics model containing a dual mass flywheel are analyzed in depth using the time-domain solver of AVL-exact PU. The results demonstrated that the simulation of 4th and 6th harmonics resonated at critical speeds of 4,195 rpm and 2,771 rpm, respectively, with angular displacement amplitudes of 0.141 deg and 0.047 deg. In fact, resonance was measured at 4,250 rpm and 3,040 rpm, with amplitudes of 0.14 deg and 0.052 deg. These two were basically consistent in key parameters. When the shaft model was started under operating conditions, the amplitudes of harmonics 1, 2, and 4 were basically consistent below 750 rpm, and there were slight differences after 750 rpm. Therefore, the AVL-based engine torsional vibration simulation model constructed has high credibility.

Patellofemoral instability in children and adolescents

Patellofemoral instability is acommon and clinically relevant disorder of multifactorial causes. Several concomitant problems such as genua valga, hyperlaxity, injuries or sports-related overuse may contribute to the development of instability and recurrent patellar dislocations. Athorough diagnosis is of paramount importance to delineate every contributing factor. This includes radiographic modalities and advanced imaging such as magnetic resonance imaging or torsional analyses. The authors recommend non-operative management (including physiotherapy, gait and proprioceptive training, orthoses) and, whenever non-operative measures fail, surgical patellar stabilization using, e.g. MPFL reconstruction.

An inspection of the metal-foam beam considering torsional dynamic responses

Metal foam is a multifunctional material with a lower specific weight, high stiffness and compressive strength, and high energy absorption. These remarkable properties make metal foams a promising candidate for conventional materials in different industrial fields. Despite numerous researches on mechanical behavior either static or dynamic of structures made of metal foams, torsional vibration analysis of metal foam structures is still uninvestigated. In this investigation, the influence of various imperfection distribution patterns on the torsional dynamic response of metal foam beams is examined within the framework of Timoshenko-Gere's theory. Two common materials i.e. SUS304 and Aluminum foams are considered the constructive materials of structure. Moreover, three imperfection distribution patterns are taken into account. The virtual work's principle has been employed to derive the torsional governing equation of metal foam beams. Then, the derived governing equation has been solved via an analytical method. The accuracy of the employed methodology has been compared with the findings of former research in the literature. Finally, the influences of different notable parameters on the variation of natural torsional frequency have been examined and demonstrated in a group of tables and diagrams.

Torsional effect analysis of high-rise reinforced concrete space grid cassette multi-tube structure system

The manuscript introduces a new structural system called the reinforced concrete (RC) space grid cassette multi-tube structure for high-rise buildings. A case study building is analyzed using this system and compared to a conventional RC frame-core tube structure. Through modal analysis in the software “Midas Gen”, the torsional effect and control indices like inter-story displacement ratio, maximum displacement, etc. are compared between the two structural systems. The results show that the space grid cassette system has smaller displacement ratios, displacements, inter-story torsion angles, and thus better torsional resistance compared to the conventional frame-core tube system. Based on these analyses, the manuscript concludes that the RC space grid cassette multi-tube structural system has superior seismic performance and is more suitable for irregularly shaped high-rise residential buildings.

Torsional vibration characteristics analysis and vibration suppression research of compressor flexible rotor system considering fit clearance

Torsional vibration characteristics analysis and vibration suppression research of compressor flexible rotor system considering fit clearance

Nonlinear modeling and torsional vibration analysis of heavy-duty vehicle powertrain system during acceleration

Nonlinear modeling and torsional vibration analysis of heavy-duty vehicle powertrain system during acceleration

Evaluating the safety of the redesigned shafting system following the propeller redesign aimed at enhancing CII and EEXI

In July 2023, the International Maritime Organization (IMO) set a target to achieve net-zero greenhouse gas emissions by 2050, introducing key measures such as the Energy Efficiency Design Index (EEDI), the Energy Efficiency Existing Ship Index (EEXI), and the Carbon Intensity Indicator (CII). The maritime industry explored adaptations, including engine de-rating, energy-efficient technologies, and propeller modifications, and beyond. This study assessed the safety implication of a redesigned shafting system, resulting in a propeller redesign to enhance the CII and EEXI on a 6500 TEU container ship built in 2006. Through an analysis of annual output per TEU from 2000 to 2015, the study focused on container ships built from 2005 to 2007 with high-output engines (9.4–9.5 kW/TEU). After selecting a sample ship, the study determined engine power limits according to the EEXI regulations and assessed their impact on the CII. Subsequently, the study redesigned the shafting system, performing torsional vibration calculations and shaft alignment analyses to ensure the safety of the modified system. While an enhanced CII rating was predicted, the tightening CII regulations imply this benefit may be short-lived, lasting approximately two years. Thus, additional measures are essential to prolong the improved CII rating.

Melting and crystallization temperatures, foaming, and fluid-induced crystallization of poly (ε-caprolactone) in compressed CO2 and N2

Melting and crystallization temperatures of poly(ε-caprolactone)(PCL) exposed to CO2 and N2 have been evaluated at pressures up to 125 bar using High Pressure Torsional Braid Analysis. It is shown that in contrast to CO2, exposure to high pressure N2 does not lead to a significant depression of Tm or Tc. Instead, these transition temperatures tend to increase in nitrogen, reflecting more of a hydrostatic pressure rather than a solvent effect. Another factor that may play a role is the fluid-induced crystallization which tends to increase the melting temperature. By conducting foaming at properly selected temperatures along the rigidity reduction paths which are scaled with respect to the melting temperatures in CO2 or N2, foams with low bulk foam densities of about 0.2 g/cm3 could be generated in CO2 at 100 bar and in N2 at 200 bar.

Numerical method for the primary torsional capacity of arbitrary steel cross sections considering nonlinear plastic behaviour

In structural design, plastic capacities of cross sections are of great importance for evaluating the capacity of steel members. Moreover, when it comes to problems of member stability, states of partial plasticisation are of interest as well. Depending on the cross section geometry and the material law to be considered, the determination can be challenging. This particularly applies to load conditions characterised by shear stress states, as for instance in the case of primary torsion (St. Venant's torsion). Simplifications are therefore often made with regard to the cross section geometry and engineering models are applied if the plastic limit moment of primary torsion Mpl,xp is to be determined. However, numerical methods allow a precise determination of properties and stress distributions of arbitrary cross section. In the present study, corresponding finite element formulations are combined with a plasticity algorithm for torsional analysis considering effects of nonlinear isotropic hardening. The approach approximates the nonlinear material law by a multilinear curve, which is stepwise evaluated based on linear hardening formulations. It allows determining states of partial cross section plasticisation for any strain or deformation state as well as the identification of the plastic limit capacity of the cross section. Results of the implemented algorithm are presented and verified for different common steel profiles showing excellent agreement to comparative studies.

Torsional vibration analysis and active anti-disturbance decoupling control of duplex trident universal joints

Torsional vibration analysis and active anti-disturbance decoupling control of duplex trident universal joints

Torsional and lateral vibration analysis of wind turbine generator bearing outer ring fault considering unbalanced magnetic pull

Rolling bearings play a critical role in wind turbine generators, operating continuously in an electromagnetic excitation environment. Their fault vibration characteristics are affected by unbalanced magnetic pull (UMP), which has received little attention in previous studies. Moreover, torsional vibration can provide advantages in bearing fault diagnosis, since it has a good signal-to-noise ratio (SNR) and it can be easily measured by the encoder. However, torsional vibration is rarely considered in the existing model of wind turbine generator. Accordingly, this paper proposes a dynamic model with 8 degrees of freedom to analyze the bearing outer ring fault characteristics of wind turbine generator under the influence of UMP, while also taking into account the torsional vibration in the model. The validity of the model is verified through experiments conducted on a test rig. The results displays modulation of the ball pass frequency outer (BPFO) harmonics with both UMP frequency and rotation frequency in lateral vibration, and this phenomenon can also be observed in instantaneous angular speed (IAS) and instantaneous angular acceleration (IAA) signals that represent torsional vibration. Besides, the lateral vibration spectrum reveals two distinct resonance bands, and simulation analysis suggested that the rotor and bearings give rise to low-frequency and high-frequency resonance, respectively. This study provides a reference for bearing faults diagnosis in wind turbine generator.