Torsional Torque Research Articles

Large-torque and fast-response electrothermal-motivated liquid crystal elastomer twisted yarn actuators

Analogous to biological muscles, twisted yarns with the capacity to output torsional torque and reversible rotation are of significant value in the development of soft robotic systems. However, how to achieve large torque while efficiently integrating electrical control elements to the soft actuators remains scientific and engineering challenges. Here, by concentric twisting a flexible silver-plated polyamide strand (SPS) with multi-layer liquid crystal elastomer fibers (LCEFs), a twisted yarn actuator with the skin-core structure that exhibits outstanding rotational motion under the electrical current control is fabricated. It has been proved that this multi-layered twisting structure efficiently improves the actuating performance. The yarn actuator can produce a peak torque of 33.4 N m kg−1 which outperforms reported commercial rotating motors and a specific power density of 21.2 W kg−1 that is comparable to the human skeletal muscle. As conceptual applications, electrical soft rotors and a novel flexible lifter have been successfully constructed based on the twisted yarn actuator, demonstrating precise torque responsiveness and controllability. Furthermore, a smart crawling fabric embedded with the twisted yarn actuators has been weaving fabricated which can crawl forward continuously and achieve the crawling stroke of 19.9 mm in 55 s and a maximum speed of 1.1 mm s−1. The research provides insights for designing soft robots employing fabric structures.

A Novel PI-Based Control Structure with Additional Feedback from Torsional Torque and Its Derivative for Damping Torsional Vibrations

This paper presents issues related to the damping of torsional vibrations in a system with elastic coupling. A novel PI-based control structure with additional feedback from torsional torque and its derivative is proposed. For the estimation of the required variables, the integral observer is proposed. Analytical expressions are presented to enable the selection of parameters of the control system. The relationship between the considered system and popular structures with a PI controller and one additional feedback from torsional torque and the derivative of torsional torque is pointed out. The proposed control structure is tested under simulation and experimental studies.

Design of Anti-Eccentric Load Sensor for Engineering Operation Early Warning Based on Particle Swarm Optimization.

The accuracy of aerial work platform weighing is essential for safety. However, in practice, the same weight placed at different locations on the platform can yield varying readings, which is a phenomenon known as eccentric load. Measurement errors caused by eccentric loads can lead to missed detections and false alarms in the vehicle safety system, seriously affecting the safety of aerial work. To overcome the influence of eccentric load, the current engineering practice relies on multiple measurements at multiple points and averaging the results to eliminate the eccentric load, which greatly increases the work intensity of workers. To address the aforementioned issues, this paper proposes a three-dimensional force/torque shear force compensation scheme based on bending torque and torsional torque for pressure. The goal is to ensure that the sensor on the aerial work vehicle platform can accurately measure the anti-eccentric load under single-point measurement conditions. A three-box structure anti-eccentric load-weighing sensor for the aerial work platform was designed. Its structure has the advantages of high mechanical strength and no radial effect, ensuring the safety of aerial work, improvement of measurement sensitivity, and enabling of real-time and accurate acquisition of force/torque in three directions. In order to further improve the measurement accuracy of 3D force/torque compensation, a particle swarm optimization algorithm was adopted to optimize the 3D force/torque shear force compensation, thereby improving the safety of engineering operations. Through the verification of a self-made testing platform, the anti-eccentric load sensor designed in this study can ensure that the measurement error of objects at any position on the platform is less than 1.5%, effectively improving the safety of high-altitude platform engineering operations.

Nonlinear characteristics of torsional stiffness of a coilable mast with triangular section

With numerous applications coilable masts in high-precision astronomical observations, such as X-ray source observations, it is important to investigate mast stiffness. To date, there have been many studies on the bending stiffness of coilable masts, but few studies on their torsional stiffness, especially regarding the nonlinear characteristics of torsional stiffness of coilable masts under large torsional deformation. In this paper, a nonlinear analysis method is presented to examine the torsional stiffness of coilable masts with triangular sections. Based on the second-order bending buckling hypothesis of battens under large torsion deformation, the nonlinear relationship between torsional torque and torsional angle is obtained by analyzing torsional deformation and force of coilable masts. This method is used to analyze the torsional stiffness nonlinearity of a certain type of coilable mast which will be used in a practical application in the future and the results are verified by simulation and testing. The comparison results show that the error is within the acceptable range, which proves the effectiveness of the proposed method.

Model Prediction and Optimization of Belt Drive System Vibration Suppression Based on Industrial Robot Joints

Addressing the vibration issues caused by torsional angle changes in the belt transmission systems of industrial robots during practical applications, this paper introduces a control strategy that integrates a Model Predictive Control (MPC) compensation mechanism. By applying the Lagrangian method, a dynamic mathematical model correlating torsional angle and torque was established, and an algorithm design combining MPC with its compensatory controller was developed. This strategy was validated in a MATLAB simulation environment. Simulation results demonstrate that, compared to traditional sliding mode control, the newly proposed controller significantly improved response speed in tracking the torsional angle's position and angular velocity, achieving enhancements of approximately 2 seconds and 1 second, respectively. This led to higher tracking accuracy and faster convergence speed, effectively enhancing the vibration suppression performance of industrial robot joint belt transmission systems.

Research on modified lumped parameter method in torsional vibration analysis of reciprocating compressor shaft

Abnormal vibrations often occur during the operation of reciprocating compressors under different load conditions. To efficiently and accurately calculate the torsional vibration response of the shafting under various working conditions, a modified lumped parameter method (MLPM) based on finite element mode modification is proposed. MLPM is derived from the lumped parameter method (LPM) and incorporates corrections to the stiffness matrix based on the multi-degree-of-freedom modal calculation using a finite element model. This allows MLPM to combine the high accuracy of finite element method (FEM) with the fast computing speed of LPM. To demonstrate the effectiveness of MLPM, an abnormal vibration compressor equipped with a stepless capacity control system is considered. MLPM is utilized to calculate the torsional natural frequency (TNF) and torsional torque response of the compressor’s shafting. The computed 1st-order TNF error between MLPM and FEM is only 0.20%. In the time domain, the torque response error of MLPM is less than 3.07%, while in the frequency domain, it is less than 0.57%. Moreover, MLPM exhibits a significantly increased calculation speed of more than 95% compared to FEM. By comparing MLPM results with torsional vibration test data, the 1st-order TNF error is found to be less than 0.50%, and the frequency-domain torque response error is no more than 8.91%. Furthermore, MLPM is effectively applied to solve the abnormal vibration problem of the compressor. It proposes a modification plan for the shafting, which successfully avoids torsional resonance and reduces the peak value of the torque response by 54.77%. These results demonstrate that MLPM is highly suitable for practical engineering applications due to its combination of high accuracy and fast computing speed.

Experimental Study on Torsional Friction of Stringing Blocks on Conductor in Tension Stringing Construction

An experimental study was conducted to analyze the torsional friction effect of stringing blocks on the conductor during tension stringing construction. By analyzing the torsional friction force of stringing blocks on the conductor, the torsional friction experimental device of the stringing blocks on the conductor was designed. The torsional friction torque of the JL/G1A-630/45-45/7 Aluminum Conductor Steel Reinforced (ACSR) under the different tensions and wrap angles passing through the stringing blocks was measured, and then the friction coefficient was obtained. The experimental results show that the torsional friction coefficient of the stringing blocks to the conductor μ decreases with the increase of the tension of the conductor and the wrap angle passing through the stringing blocks. The relationship between the coefficient of friction and the wrap angle and tension of the conductor passing through the stringing blocks is obtained by fitting, and the formula for calculating the torsional frictional torque is obtained.

Torsional actuation and vari-stiffness characteristics of SMA/basalt hybrid braided composite tubes

Shape memory alloy hybrid composite (SMAHC) tubes have the potential to actively control the torsional stiffness of structures. In this work, shape memory alloy (SMA) wires orthogonally braided with basalt fiber were heated by electricity to generate the torsional torque of the SMAHC tube, and then the torsional stiffness of the tube was measured. The macroscopic finite element model of the SMAHC tube was established to assist in the analysis of the torsional stiffness variation before and after heating. According to the experimental results, the actuating torsional ability was affected by the phase transformation recovery force of SMA. The active control of torsional stiffness depends on the change of SMA modulus, the magnitude and direction of SMA wires’ recovery force, and the thermodynamic properties of matrix at different temperatures. Then an evaluation model for the torsional stiffness control effect was proposed. These research results can be used for the adaptive control of the stiffness and vibration characteristics of rotating composite structures, and provide a novel and effective method for the control of structural torsional characteristics with lightweight effects.

Two-DoFs active deflection control of MSW based on fractional-order integral SMC method

The active deflection of the rotor shaft in the magnetically suspended wheel (MSW) could generate three-dimensional torques to realize the attitude control of spacecraft, but the torsional torque and nonlinear torque could affect the control precision of active deflection. Therefore, a fractional-order integral sliding mode control (SMC) method is designed to improve the control precision and robustness of active deflection. Firstly, the electromagnetic (EM) torques generated by the three degrees of freedom (DoFs) axial magnetic bearing (MB) are analyzed, and the torsional torques of two-DoFs MB are developed during the active deflection process of the flywheel rotor. Results show that the active deflection is affected by the nonlinear EM torques and torsional torques. Furthermore, the fractional-order integral SMC law is designed to improve the control performance of active deflection, and the closed-loop stability of active deflection with the fractional-order integral SMC method. Finally, the simulations and experiments are conducted to verify the control performances of the proposed method, and experiment results indicate that the angle obviation of active deflection is reduced by 50% compared to the general PID control with the cross-feedback model.

An efficient power control strategy for active mitigation of blade in‐plane fatigue loading in PMSG‐based wind turbines

AbstractThis paper assesses the dynamic performance of permanent magnet synchronous generator‐based wind turbine (WT) regarding the blade in‐plane fatigue loads once the WT is controlled in power control mode. Blade in‐plane oscillations, associated with the poorly blade in‐plane modes, can be excited by turbulent winds or grid disturbances that may lead to damage of the blades and reduce the drive‐train reliability. To overcome this drawback, at first, a model with three degrees of freedom is extracted for the drive‐train system, and then, an active mitigation approach is proposed to mitigate the blade in‐plane oscillations. The proposed method can effectively suppress the blade in‐plane vibrations by adding a supplementary term into the power control loop that is proportional to the speed difference between the blade and generator. The speed difference between the blade and generator is obtained by estimation of the blade‐hub and hub‐generator shaft torsional torques. Next, the performance of the proposed active mitigation approach is examined by the modal and frequency response analyses and time‐domain simulations. Finally, it is shown that the proposed approach has superior performance over the conventional approaches based on the simplified drive‐train model and crossing the measured generator speed through a band‐pass filter.

Account of additional factors for damping torsional oscillations

Some parameters are influenced by the turbine unit's torsional oscillations. The fundamental comes from damping these oscillations, which are brought on by a departure in the turbine blades' speed from the device's prediction of the steam volume, and attenuation of fluctuations due to the distribution of energy in the turbine's productive components. The usual single-machine infinite bus system is used for the analysis. For various turbine-generator shafts and various generator operating situations, rotating mass mechanical system evaluations for small-signal stability and large disturbance are conducted. It is demonstrated that the shaft's “structural' damping (H) and “steam' damping (Kn) coefficients have a considerable impact on the damping of torsional modes. The goal of this work is to determine the effect of changing the damping factors in the mathematical model of the steam turbine shaft on the system's static stability, as well as the extent to which these variables' limits on damping rotational oscillations on the maximum torsional torques generated in the shaft masses. The mathematical model of the steam turbine shaft with a single machine and transmission line to an infinite bus system was simulated using Dymola software, and the static and dynamic effects of damping factors (H) and (Kn) on system stability were demonstrated. By evaluating the best case for parameters with the least influence on the system's stability, the results were obtained by changing the factors (Kn) from 0.005 to 0.5 and (H) from 0.005 to 0.2 and the extent of its effect on the maximum torque of the steam turbine masses and reducing it by 8.4 %, as well as by reducing the settling time of the system after disturbances occur and reaching to Steady state by about 90 %.

Evaluation of torsional strength and torque presentation of coated rectangular stainless steel archwires, an in vitro study.

An in vitro experimental study was performed to evaluate the torsional strength and torque released by esthetic coated archwires. A total of 52coated (study group) and 52stainless steel (control group) rectangular archwires from two manufacturers (brandI: Gestenco International AB, Gothenburg, Sweden and brandII: Ortho Technology, Lutz, FL, USA) in two sizes (0.019 × 0.025 and 0.017 × 0.0250-inch) were evaluated. The straight parts on both ends of each preformed archwire were cut in 30 mm segments. Aspecially designed experimental device was attached to the universal testing machine (Model Z020, Zwick Roell, Ulm, Germany) to measure torsional strength and to calculate the clinically significant torque interval. The groups were compared based on their brand, presence of coating and size using three-way analysis of variance (ANOVA) test at asignificance level of 5%. The results revealed that coating of the wires of brand1 resulted in asignificant reduction of torsional strength in both wire sizes (P-value = 0.0001). For the wires of brand2, coating of the 0.017 × 0.025-in wire resulted in asignificant reduction in torsional strength. However, for the 0.019 × 0.025 in wire size, the presence of coating significantly increased the torsional strength (P-value = 0.0001). Coating did not affect the measured clinical torque interval of the analyzed wires when atorque between 5and 20 Nmm was applied (P-value = 0.062). Mechanical behavior of coated archwires depends mainly on the thickness of their inner core alloy. Reduction in the diameter of the inner alloy resulted in reduced torsional strength. Despite lower mean torsional strength, in the settings of this study, coated and conventional wires demonstrated comparable torque angles if loaded in the typical range of activation.

Steerable and Agile Light‐Fueled Rolling Locomotors by Curvature‐Engineered Torsional Torque (Adv. Sci. 30/2023)

Steerable and Agile Light‐Fueled Rolling Locomotors by Curvature‐Engineered Torsional Torque (Adv. Sci. 30/2023)

Steerable and Agile Light-Fueled Rolling Locomotors by Curvature-Engineered Torsional Torque.

On-demand photo-steerable amphibious rolling motions are generated by the structural engineering of monolithic soft locomotors. Photo-morphogenesis of azobenzene-functionalized liquid crystal polymer networks (azo-LCNs) is designed from spiral ribbon to helicoid helices, employing a 270° super-twisted nematic molecular geometry with aspect ratio variations of azo-LCN strips. Unlike the intermittent and biased rolling of spiral ribbon azo-LCNs with center-of-mass shifting, the axial torsional torque of helicoid azo-LCNs enables continuous and straight rolling at high rotation rates (≈720rpm). Furthermore, center-tapered helicoid structures with wide edges are introduced for effectively accelerating photo-motilities while maintaining directional controllability. Irrespective of surface conditions, the photo-induced rotational torque of center-tapered helicoid azo-LCNs can be transferred to interacting surfaces, as manifested by steep slope climbing and paddle-like swimming multimodal motilities. Finally, the authors demonstrate continuous curvilinear guidance of soft locomotors, bypassing obstacles and reaching desired destinations through real-time on-demand photo-steering.

Twistocaloric Modeling of Elastomer Fibers and Experimental Validation.

The twistocaloric effect is attributed to the change in entropy of the material driven by torsional stress. It is responsible for the torsional refrigeration of fiber materials that has been widely exploited as one of the solid-state cooling techniques with high efficiency and low volume change rate. The lack of theories and mathematical models of twistocaloric effect, however, limits broad applications of torsional refrigeration. In this work, a twistocaloric model is established to capture the relationship between twist density and temperature variation of natural rubber fibers and thermoplastic elastomer yarns. An experimental setup consisting torsion actuator and torque sensor coupled with a temperature measurement system is built to validate the model. Using the Maxwell relationship, twistocaloric coefficient is measured by quantifying the thermal effect induced by torsion under shear strain. The experimental characterization of the twistocaloric effect in natural rubber fiber and thermoplastic elastomer yarn are consistent with the theoretical predictions.

Mechanical properties and biocompatibility of a novel miniscrew made of Zr70Ni16Cu6Al8 bulk metallic glass for orthodontic anchorage

The purpose of the present study was to fabricate a miniscrew possible for clinical application using Zr70Ni16Cu6Al8 bulk metallic glass (BMG), which has high mechanical strength, low elastic modulus, and high biocompatibility. First, the elastic moduli of Zr-based metallic glass rods made of Zr55Ni5Cu30Al10, Zr60Ni10Cu20Al10, Zr65Ni10Cu17.5Al7.5, Zr68Ni12Cu12Al8, and Zr70Ni16Cu6Al8 were measured. Zr70Ni16Cu6Al8 had the lowest elastic modulus among them. Then, we fabricated Zr70Ni16Cu6Al8 BMG miniscrews with diameters from 0.9 to 1.3 mm, conducted a torsion test, and implanted them into the alveolar bone of beagle dogs to compare insertion torque, removal torque, Periotest, new bone formation around the miniscrew, and failure rate compared with 1.3 mm diameter Ti-6Al-4 V miniscrew. The Zr70Ni16Cu6Al8 BMG miniscrew exhibited a high torsion torque even if the miniscrew had a small diameter. Zr70Ni16Cu6Al8 BMG miniscrews with a diameter of 1.1 mm or less had higher stability and lower failure rate than 1.3 mm diameter Ti-6Al-4 V miniscrews. Furthermore, the smaller diameter Zr70Ni16Cu6Al8 BMG miniscrew was shown, for the first time, to have a higher success rate and to form more new bone around the miniscrew. These findings suggested the usefulness of our novel small miniscrew made of Zr70Ni16Cu6Al8 BMG for orthodontic anchorage.

Dual-Motor Coordination for High-Quality Servo With Transmission Backlash

The dual-motor drive is common in many heavy-duty swinging arm servo systems. A well-tuned dual-motor drive can provide better stability and durability than the regular single motor servo. However, the backlash is usually unavoidable in the heavy transmission chains. In this article, the issues provoked by the backlash are resolved by a virtual average motor model and a simple anti-backlash torsion torque. The transient performance is guaranteed by the dual-motor synchronous drive, and the anti-backlash strategy is only enabled when the load is approaching the reference position. The challenge is that the motion system structure is transforming during this transition. The model predictive control combined with the extended state observer is applied to get adaptive in this scenario. The expected effect is that the servo can track the desired position with high precision and high response. The scheme is comprehensively validated and evaluated in an experimental servo setup with a dual-motor drive.

Torsional oscillation suppression-oriented torque compensate control for regenerative braking of electric powertrain based on mixed logic dynamic model

This paper presents a novel torsional oscillation suppression-oriented torque compensate control for regenerative braking (TS-RTC) of electric powertrain, which is based on the gear-pair backlash and half-shaft flexibility-considered dynamic model of regenerative braking in electric powertrain (REP). According to the characteristics of transition from driving mode to regenerative braking mode (DM-to-RM), the dynamic models under different stages are transmitted into an equivalent mixed-logical dynamical (MLD) hybrid model. MLD-based hybrid braking system model and hybrid model predictive control are adopted to design the TS-RTC strategy, in which the torsional oscillation suppression-oriented cost function proved efficient in improving the regenerative braking performance during DM-to-RM process. Simulations and REP hardware in the loop test show that the fluctuation of half shaft torque are efficiently suppressed and the vehicle drivability is improved.

Fused Deposition Modeling and Characterization of Heat Shape Memory Poly(lactic) Acid-Based Porous Vascular Scaffold.

Shape memory polymers have received widespread attention from researchers because of their low density, shape variety, responsiveness to the environment, and transparency. This study deals with heat-shape memory polymers (SMPs) based on polylactic acid (PLA) for designing and fabricating a novel porous vascular scaffold to treat vascular restenosis. The solid isotropic material penalization method (SIMP) was applied to optimize the vascular scaffolds. Based on the torsional torque loading of Hyperworks Optistruct and the boundary conditions, the topological optimization model of a vascular scaffold unit was established. Forward and reverse hybrid modeling technology was applied to complete the final stent structure's assembly. The glass transition temperature for the present SMPs is 42.15 °C. With the increase in temperature, the ultimate tensile strength of the SMPs is reduced from 29.5 MPa to 11.6 MPa. The maximum modulus at room temperature was around 34 MPa. Stress relaxation curves show that the material classification is a "thermoset" polymer. The superb mechanical properties, the transition temperature of the SMPs, and the recovery ratio made it a feasible candidate for a vascular scaffold. A circular tube based on the shape memory polymers was presented as an example for analyzing the recovery ratio in an unfolding state. A higher recovery ratio was obtained at a temperature of 65 °C with a tube thickness of 2 mm. Finally, the proposed porous vascular scaffold was successfully fabricated, assessed, and compared with the original and previously developed vascular scaffolds. The proposed scaffold structure regains its initial shape with a recovery ratio of 98% (recovery temperature of 47 °C) in 16 s. The tensile strength, Young's modulus, and bending strength of the proposed scaffold were 29.5 MPa, 695.4 MPa, and 6.02 MPa, respectively. The results showed that the proposed scaffold could be regarded as a potential candidate for a vascular implantation.

The Impact of Non-constant Inertia and Nonlinear Damping on the Torsional Vibration Characteristics of Internal Combustion Engine Including External Forces

Failures of the crankshaft-slider mechanism are the most reasons that affect the durability and operational reliability of the internal combustion engine. An accurate and sophisticated nonlinear dynamic model overcomes the obvious simulation errors of linearized models. The present work studies the effect of the non-conservative forces and nonlinear damping on the torsional vibration of single-cylinder internal combustion engines. Comprehensive dynamic modeling based on a developed expression for the instantaneous kinetic energy of the reciprocating parts and a general model of the overall kinetic energy of the system in terms of the inertia parameters were derived. The effect of variable inertia and nonlinear damping on the damped forced response of slider-crank assembly of the engine was investigated using the numerical integration method. The numerical results show that the phenomenon of secondary rolling excitation torque is well activated and gives arises to variation of frequencies and their corresponding amplitudes. Also, the amplitude of the external excitation torque is strengthened by the secondary excitation inertia torque and introduces multi resonance amplitudes phenomenon and widening the critical range of engine speed which results in producing of dangerous vibrational stress amplitudes. Also, the damped forced results indicate that the presents of damping lead to a vital reduction in the amplitude of torsional displacement and excitation torques. The present work aims to enhance nonlinear dynamic modeling and introduces more reliable design for reciprocating engine crankshaft assembly.