Preload Torque Research Articles

Assembly and operation optimization of proton exchange membrane water electrolyzer for performance enhancement

Abstract Proton exchange membrane water electrolysis (PEMWE) for hydrogen production possesses wide-ranging and rapid dynamic response capabilities, offering promising applications in the consumption of new energy sources and the dynamic balancing of power grids with a high proportion of renewable energy. The assembly and operating conditions of PEMWE significantly affect its performance. Therefore, thoroughly studying and understanding the influence of PEMWE’s assembly and operating conditions on water electrolysis performance are crucial for enhancing PEMWE’s performance and promoting its applications. In this research, the influence of installation preload torque, feedwater flow rate, and operating temperature on the performance of the electrolyzer, including the electrochemical active specific surface area (ECSA), high-frequency resistance (HFR) and various types of polarizations (including activation polarization, ohmic polarization, and mass transfer polarization) during the operation of the electrolyzer, were detailedly investigated. The results showed that the optimal preload torque and operating temperature for the electrolyzer were 3 Nm and 80°C. Under these conditions, an optimized PEMWE performance would be achieved by ensuring that the feedwater flow rate exceeded the water consumption during electrolysis.

Shedding Light on the Failure Factors of Subsea Critical Fastener Bolts

Offshore facilities, such as oil and gas rigs, wind turbines, and related subsea equipment, typically use flanges fastened using bolts and nuts as the main connectors. In this study, multidisciplinary parameters, namely the preload torque used to tighten bolts, simulated subsea water currents, water temperature, and impressed current cathodic protection, were applied to ASTM A193 B7 bolts. An experimental supervisory control and data acquisition system was designed to obtain measurements every 5 min throughout a 21-day experiment. Finite element analysis was performed to predict the structurally vulnerable areas of the bolts. A strong correlation was found between the reference electrode readings and the measured electrical current, tightening torque, and water temperature. As the water temperature rises during the day, the reference electrode reading becomes less negative and the electrical current decreases. Subsea water currents cause about a four-time increase in the bolt corrosion rate, with unprotected bolts suffering a nine-time-higher corrosion rate than protected bolts. A unique supply–demand interaction is observed; less protection is supplied to areas with lower corrosion rates (lower demand for protection). Finally, scanning electron microscopy examination reveals new insights into the failure mechanisms of subsea bolts.

Bidirectional motion characteristics of resonant inertial impact rotating piezoelectric motor based on self-clamping structure

A new working principle for multimodal excitation of a resonant bidirectional rotary inertial impact piezoelectric motor with a self-clamping structure was developed based on previous research on piezoelectric motors. Unlike previous piezoelectric motors that relied on single harmonic waves for unidirectional rotation, in this motor, we can simply change the driving signal characteristics of the motor without changing the structure of the piezoelectric motor to excite multiple vibration modes, thereby achieving rotation in both directions. Compared with other bidirectional resonant motors, the structure and control signal are simpler. The finite element simulation software COMSOL5.5 was used to simulate the working mode of the motor, and the results were in good agreement with the final experiment. During the experiments, the optimal operating frequency of the motor prototype was 900 Hz. The maximum output speed of the motor prototype was 3.9 rad/s, the maximum output torque was 15 N mm, and the maximum resolution was 0.248° under the conditions of 240 Vp-p voltage, 900 Hz frequency, and 7.8 N mm preload torque.

Pull-out behavior of torque-controlled expansion anchors in HPSFRC under different installation conditions

To study the pull-out behavior of torque-controlled expansion(TCE) anchors on high-performance concrete(HPC) and high-performance fiber-reinforced concrete(HPSFRC) substrates, 28 pull-out tests are set up. Different installation conditions of anchors, including the embedment depth(Hef) and the preload torque(Tinst), and the types of substrates, including no-fiber HPC and HPSFRC with 1% fiber content, are considered in the test. The split tensile(ft) and compressive strengths(fcu) of concrete are measured to evaluate the influences of fibers on the properties of concrete. Pull-out tests are conducted TCE anchors installed in C70 HPC/HPSFRC cylinder specimens by the displacement-control loading method. From test results, the relationship between failure mode, load-displacement behavior, pullout load-bearing capacity(Nu) and installation factors (Hef, Tinst, etc.) are analyzed. The preload loss law of the fastener system within 24 h is monitored. It is found that the larger Tinst leads to a larger preload loss rate, and the loss in Tinst tends to be stable within 5–7 h. A modified model of Nu of TCE anchors in HPSFRC is proposed. The prediction accuracy of the modified model and the existing models (CCD model, Toth et al's model) is compared; both CCD and Toth et al's model underestimate Nu, which would lead to uneconomical over-design, and the prediction results of the modified model are in a good agreement with the experimental results.

Effect of Preload on Tensile Fracture of Variable Cross-Section Bolts: Experiment and Simulation

High-strength bolts are widely used in structural connections, and the preload affects the failure behavior of bolts. In this paper, a variable cross-section bolt (VCSB) with weakened strength to induce fracture is designed. Quasi-static tensile experiments with different preload torque values were performed on the VCSB. The preload torques of 0, 430, 610, and 820 N·m were applied to the VCSB connection structures before the test. The load–displacement curves obtained by the test could be divided into three stages: the initial elastic phase, the yield phase, and the rapidly necking phase. As the preload increased, the stiffness of the initial elastic phase increased from 101.21 kN/mm to 270.64 kN/mm and the fracture displacement DC decreased from 10.54 mm to 8.42 mm. Finite element models were developed to simulate the failure process of VCSB under tensile loads. The difference between the FB and DC values in the simulation results and the test is within 2%. The simulations were carried out by adjusting the prestress from 0 to 650 MPa. The results show that the value of preload force has no effect on the FB of VCSB, but greatly influences the DC and FC of the connection.

A resonant inertial impact rotary piezoelectric motor based on a self-clamping structure

A resonant inertial impact rotary piezoelectric motor based on a self-clamping structure is designed, assembled, and tested. The designed piezoelectric motor mainly includes a rotor (two vibrators, preload mechanism, and intermediate connection mechanism), a clamping mechanism, and another auxiliary mechanism. The piezoelectric ceramic sheet on the rotor drives the vibrator to swing under the excitation of a single harmonic wave. Because there is a clamping mechanism formed by the combination of clamp baffle and fixed clamp ring, thus the half-cycle resonant rotation of the rotor can be effectively completed, and repeated harmonic excitation can realize the unidirectional continuous rotation and swing of the rotor. The whole excitation process of the motor is in a resonance state, which has significant advantages, such as low friction and simple structure, compared with the traditional quasi-static piezoelectric motor. The structure of the piezoelectric motor is designed and analyzed using COMSOL5.5 software and then the motor performance is tested and analyzed by building an experimental platform to verify the feasibility of the motor design. The final experimental results show that the optimal working frequency of the piezoelectric motor is 150 Hz, which is consistent with the characteristic frequency of the simulation. When the motor prototype is under the conditions of optimal operating frequency 150 Hz, voltage 240 Vp-p, and preload torque 7.8 N.mm, the maximum angular speed can reach 2.4 rad/s, the maximum load can reach 27.8 N mm and the maximum resolution of the movement angle can reach 0.941°.

Vibration Energy Coupling Behavior of Rolling Mills under Double Disturbance Conditions

The operation of the world’s first multimode continuous casting and rolling F3 (3rd finishing mill stand) finishing mill was hampered by frequent vibrations. Mill vibrations were found to be caused by the transmission and coupling of vibration energy flow. In this study, an overall finite element model of the F3 stand is established based on the structural sound intensity method and harmonic response analysis method, and then, the intrinsic energy flow modes and energy flow harmonic response of the F3 stand are obtained. Further, the effects of the steady-state rolling force variation, preload torque variation, rolling force fluctuation, torque fluctuation, and its phase angle difference on the vibration energy flow of the mill are analyzed. Finally, the effects of the mill damping ratio, strip width, and strip modulus on the vibration energy flow under double dynamic load are discussed to reveal the inherent characteristics of the mill vibration energy flow. The results show that the vibration energy flow of the mill increases with the increase of strip modulus, rolling force, and moment fluctuation; the phase angle difference of rolling moment shows a “V” trend change on the vibration energy flow; the change of strip width has a greater effect on the vibration energy flow of the vertical system; and for the damping ratio of 0.01–0.1, the reduction of the vibration energy flow at all excitation frequencies is obvious.

Resonant-type rotating piezoelectric motor with inchworm-inertia composite impact.

A resonant-type rotating piezoelectric motor with inchworm-inertia composite impact was designed and manufactured. It mainly comprises a stator, rotor, support shaft, and frame. The motor stator includes a clamp, driver, central connecting block, preload structure, and other auxiliary mechanisms. The clamp and driver of the motor work in a resonant state. The motor structure was optimized by using the finite element software COMSOL 5.2. Through the finite element simulation analysis, the first-order bending vibration of the clamp and the driver was selected as the working mode, and the consistency of the resonance frequency coupling was optimized and adjusted. By coordinating the bending vibration of the clamp and driver in the vertical staggered direction, the clamping foot drives the rotor to realize the unidirectional continuous rotation. The motor prototype was designed and processed, while the experimental device platform was established to verify the working principle of the motor, and the comprehensive performance of the motor was analyzed and tested. When the input driving voltage was 240VP-P, the driving frequency was 161Hz, and the preload torque of the motor was 6.9 N mm, the maximum no-load speed of the motor reached 3.23 rad/s and the maximum load torque reached 10.35 N mm. Under the same conditions, the maximum resolution of the motor rotation angle was 0.69°.

Effects of abutment screw preload and preload simulation techniques on dental implant lifetime

BackgroundThis study aimed to investigate how the predicted implant fatigue lifetime is affected by the loss of connector screw preload and the finite element analysis method used to simulate preload. MethodsA dental implant assembly (DI1, Biomet-3i external hex; Zimmer Biomet) was scanned using microcomputed tomography and measured using Mimics software (Materialise) and an optical microscope. Digital replicas were constructed using SolidWorks software (Dassault Systèmes). The material properties were assigned in Abaqus (Dassault Systèmes). An external load was applied at 30° off-axial loading. Eight levels of connector screw preload (range, 0-32 Ncm) were simulated for DI1. This assembly and an additional model (DI2) having a longer and narrower screw were compared regarding their fatigue limits (using fe-safe software [Dassault Systèmes]) for 2 preloading methods: (1) adding preload torque or (2) adding bolt axial tension. ResultsThe maximum von Mises stresses of DI1 (on the connector screw threads) with and without preload were 439.90 MPa and 587.90 MPa. The predicted fatigue limit was the same for preloads from 100% through 80% of the manufacturer’s recommendation and dropped precipitously between 80% and 70% preload. Adding a preload torque on the screw resulted in a more uniform stress distribution on the screw compared with bolt axial tension, especially for DI2, which had a longer and narrower screw than DI1. ConclusionsA substantial loss of preload can be accommodated without compromising the fatigue resistance of this dental implant. Computer models should be constructed using torque instead of a bolt axial tension.

Resonant-type inertial impact piezoelectric motor based on a cam locking mechanism.

A new resonant-type inertial impact piezoelectric motor based on a cam locking mechanism was designed, assembled, and tested. The motor is composed of a stator, a rotor, and other auxiliary components. The cam clamping foot of the stator in contact with the inner surface of the rotor forms a cam locking mechanism, which can make the resonant vibration of the stator effective in a half cycle. By receiving sinusoidal signals, the stator generates bending deformation due to the regular deformation of the piezoelectric plate, which drives the cam clamping foot to move and subsequently causes the rotor to rotate. COMSOL5.4 finite element analysis software was used to design the structure of the piezoelectric motor, and an experimental device was built to evaluate and verify the performance of the motor. The maximum no-load speed of the prototype reached 21.61 rpm and the maximum load torque of the motor was 84 N mm under a driving voltage of 360Vp-p and a driving frequency of 388Hz. The motor achieved a net efficiency of 5.6% under a preload torque of 2 N mm with the same condition. The maximum resolution of the motion angle of the new motor prototype was 0.0748° with a driving voltage of 160Vp-p and the same frequency.

Finite Element Analysis of Stress in Bone and Abutment-Implant Interface under Static and Cyclic Loadings.

Objectives:The success of implant treatment depends on many factors affecting the bone-implant, implant-abutment, and abutment-prosthesis interfaces. Stress distribution in bone plays a major role in success/failure of dental implants. This study aimed to assess the pattern of stress distribution in bone and abutment-implant interface under static and cyclic loadings using finite element analysis (FEA).Materials and Methods:In this study, ITI implants (4.1×12 mm) placed at the second premolar site with Synocta abutments and metal-ceramic crowns were simulated using SolidWorks 2007 and ABAQUS software. The bone-implant contact was assumed to be 100%. The abutments were tightened with 35 Ncm preload torque according to the manufacturer’s instructions. Static and cyclic loads were applied in axial (116 Ncm), lingual (18 Ncm), and mesiodistal (24 Ncm) directions. The maximum von Mises stress and strain values were recorded.Results:The maximum stress concentration was at the abutment neck during both static and cyclic loadings. Also, maximum stress concentration was observed in the cortical bone. The loading stress was higher in cyclic than static loading.Conclusion:Within the limitations of this study, it can be concluded that the level of stress in single-unit implant restorations is within the tolerable range by bone.

Novel piezoelectric rotary motor on the basis of synchronized switching control.

A novel piezoelectric rotary motor (PRM) on the basis of synchronized switching control was designed, fabricated, and tested to achieve high speed, high efficiency, and high torque. The new motor mainly consists of a vibrator working in the resonance state as the driving element of the PRM and a clutch working in the quasi-static state to control the shaft for unidirectional rotation. The finite element method software COMSOL Multiphysics 5.4 was used to design the structure of the motor and determine the feasibility of the design mechanism of the PRM. Moreover, an experimental setup was built to validate the working principles and evaluate the performance of the PRM. The prototype motor outputted a no-load speed of 7.21 rpm and a maximum torque of 54.4 N mm at a vibrator driving voltage of 120 Vp-p and a clutch driving voltage of 200 Vp-p. The motor achieved a net efficiency of 15.6% under the preload torque of 3 N mm. The average stepping angle of the motor with no-load was 0.068°, when the voltages applied to the clutch and the vibrator were 200 Vp-p and 120 Vp-p, respectively, with the frequency of 512 Hz.

Abutment screw torque changes with straight and angled screw-access channels

Statement of problemAngle-correcting options allow the use of screw-retained implant prostheses in situations where an implant has been placed with a facial inclination. However, manufacturers have different recommended torque values, and it is unclear whether the performance of these designs is equivalent to that of the traditional screw-retained crowns (SRCs) when subjected to cyclic loading forces. PurposeThe purpose of this in vitro study was to compare torque differences between conventional straight-line screw access and angulated access SRCs before and after simulated functional loading. Material and methodsFive groups consisting of 10 SRCs and implants were formed: Nobel Biocare zirconia crowns with 20-degree access channels (NB-20); Dynamic Abutment Solution zirconia crowns (DA-20) with 20-degree access channels; Core3dcentre angle correction zirconia crowns with 20-degree access channels (C3D-20); Nobel Biocare zirconia crowns with 0-degree access channels (NB-0); and gold alloy crowns cast to Nobel Biocare Gold-Adapt abutments (GA-0). Each specimen underwent thermocycling before cyclic loading. A preload torque based on the manufacturer’s recommendation was applied to each crown placed on an implant. Reverse torque measurements were obtained for each specimen before cyclic loading. Each implant-abutment assembly was then cyclic loaded at 0 to 100 N at 10 Hz for 1 million cycles. Reverse torque measurements were obtained after cyclic loading and the percentage difference calculated. ResultsNo significant percentage torque loss differences were observed between the 0-degree and 20-degree SRCs after cyclic loading. No significant differences were seen among the angulated access channel crowns. DA-20 and C3D-20 specimens had significantly higher torque loss compared with the NB-0 group. The C3D-20 group reported the largest percentage torque loss (34.5%) among the angulated access screw channel groups. The GA-0 group reported the largest percentage torque loss of all the groups (35.9%). No crown mobility or other complications were observed in any of the groups after cyclic loading. ConclusionsAngulated access channel crowns performed comparably with conventional straight-line screw access SRCs with regard to percentage torque values after cyclic loading. Angulated access channel crowns with lower manufacturer recommended torque values had higher percentage torque differences.

Parametric Study of Bolt Clamping Effect on Resonance Characteristics of Langevin Transducers with Lumped Circuit Models.

We recently proposed a numerical model using equivalent circuit models to analyze the resonance characteristics of Langevin transducers and design them in a systematic manner. However, no pre-load torque biased by a metal bolt was considered in the model. Here, a parametric study is, therefore, carried out to reveal how model parameters are adapted to incorporate the pre-compression effect into our existing model. Analytical results are compared with corresponding experimental data, particularly regarding the input electrical impedance and effective electromechanical coupling coefficient for the transducer at resonance modes. The frequency response of input impedance is presented as a function of torque, both theoretically and experimentally. For 10.0 N·m bias, for instance, both resonance and anti-resonance frequencies are calculated as 38.64 kHz and 39.78 kHz, while these are measured as 38.62 kHz and 39.77 kHz by the impedance analyzer. The impedance difference between these cases is 14 Ω at resonance and 9 kΩ at anti-resonance, while the coupling coefficients in both cases become 0.238 and 0.239, respectively. Hence, these test results are closely matched with their theoretical values. Consequently, this study provides a quantitative guideline that specifies the pre-loading condition of bolt clamps with proper parameter settings to predict the intended resonance characteristics of Langevin transducers.

Studying the Effects of Mechanical Loads and Environmental Conditions on the Drive-Axle Performance

The paper discusses the problem of achieving the required output parameters of a truck drive under various operating conditions. The authors enumerate the final-drive and differential mechanical efficiency, the pre-load torque in the final-drive bearing assembly, the friction coefficient, and the differential locking factor as the most significant technical parameters of the drive axle and its components. The main factors that affect these parameters during operation are: (i) mechanical loads that transmission is exposed to when transmitting the torque from the engine to the drive wheels; (ii) the effects of external thermal and dynamic loads when driving on an uneven surface or in cold / hot climates. The paper describes the main dependences between the final-drive processes and the inter-wheel differential processes; it also demonstrates how the aforementioned factors affect the output parameters of the component. The assumptions hereof are based on the results of bench and field truck tests, including adverse-climate tests. We herein propose a method for estimating the drive-axle load, which is based on the weighted values of the aforementioned factors. We prove it feasible to use auto-adjusted heating of the drive-axle components. The degree of thermal exposure shall be determined with due account of environmental conditions, surface conditions, engine and transmission parameters. The control algorithm is supposed to automatically take into account any change in one or more factors. This approach to controlling the output parameters helps improve the efficiency and the longevity of the drive axle and truck as a whole.

Experiment research on static and dynamic performance of precision cable-drum drive

The elastic slip and extension of a cable are important problems for a precision cable-drum drive system. Adjusting the design parameters (preload force, payload and so on) is an effective way of improving transmission performance. At present, most researchers focus on sliding mechanisms, Euler’s equation improvement and engineering applications. The effect of design parameters on the transmission performance has not been deeply investigated. In this paper, the static and dynamic performance of a cable-drum drive system was explored for improving precision and response, and the effect of preload force and payload on the static and dynamic performance was analyzed. The static performance was evaluated by the transmission error, which was determined by measuring the rotational angle of input and output drum using SCANCON encodes. The dynamic performance was evaluated by the response bandwidth, which was determined by measuring the amplitude-frequency and phase-frequency curve of cable-drum drive system using TIRA GmbH vibration test system. The results show that the maximum transmission error is 0.75 mrad at a rotational range of 180° when the external torque is 0.19 N×m. The transmission error increases with the increase of the drum rotation angle. The transmission error increases with the increase of the preload force and external torque. The response bandwidth can reach 56 Hz when the payload inertia is 0.0145 kg×m2, which decreases with increase of payload inertia. However, the preload force has little obvious influence on the response bandwidth when the preload force is changed from 99.85 N to 496.99 N. These results are helpful for the design improvement and theory research of precision cable-drum drive system in future.

Nonlinear response of a flanged fastened joint due to acoustical sine sweep excitation

Fastened joints can significantly complicate the prediction of damping and resonance frequencies of built-up systems. This complexity often leads to over-designing for safety, which drives up manufacturing and operational costs. To improve understanding of the dynamic response of fastened joints, impact hammer and acoustically driven excitation of fastened plates at a flange have been measured. These findings add experimental data that are not well represented in the literature for such joints. The structure was excited acoustically, and acceleration was measured at multiple locations on the flange and plate. Backbone curves were generated with sinusoidal sweeps of acoustic input energy. These curves highlight the nonlinearity of the system, which varies according to fastener preload. Generally, as preload torque values decrease, nonlinearity increases with shifts observed in damping, stiffness, and resonance frequency. Data presented will be used to create a model for better predicting the global dynamic properties of built-up structures.

A method for monitoring bolt torque in a composite connection using an embedded fiber Bragg grating sensor

This work presents a new method for monitoring the preload torque in a composite bolted connection using an embedded fiber Bragg grating sensor. A unique washer was designed to impose a specified nonuniform strain field across the grating, causing distortion in the reflected optical spectrum. Using the full-width at half maximum bandwidth of the Bragg reflection spectrum as the preload-sensitive feature, it is shown that this feature increases monotonically—and quite linearly—with increasing applied bolt torque. It is also demonstrated that, although distorted, the spectral structure of the sensor is maintained such that it is simultaneously able to function in its typical use as a uniaxial strain sensor, thus essentially creating a dual-purpose sensor. The computational design approach is validated with a prototype experiment.

Experimental Analysis of Dynamic Characteristic for Automatic Tensioner

Experimental method and parameters to investigate the dynamic performances of an automatic tensioner are discussed. Parameters to evaluate the dynamic performances of a tensioner include dynamic stiffness, loss angle and equivalent viscous coefficient. Dynamic stiffness and loss angle can be measured directly, and the equivalent viscous coefficient can be calculated by torque-angular displacement loop which identified with the parameters including dynamic stiffness, loss angle, pre-load torque, pre-load angular displacement, excitation amplitude and excitation frequency. In this paper, the influences of excitation amplitude, excitation frequency and pre-load torque on the dynamic characteristics of tensioner are measured and investigated.

Pre-Load Torque Responses for Flexibility in Single Link Manipulator

The Research article includes Model Torque Responses for flexibility of single link manipulators using Linearization Technique named as a LCQ. Manipulators are nothing but one type robotic arms commonly used in the industry .Here the controller design technique used for controlling manipulator was Linear Quadratic Controller Design. Generally the robotic arms are non-linear in nature. In order to control the non-linearity of manipulator and angular displacement, state space technique is used. The topology explains dynamic characteristics occurring in abnormal working condition torque responses are modified by using Linear Quadratic Controller Design Technique. The design method approach in state space control strategy. The dynamic torque responses of single link manipulator in abnormal condition and also using LCQ Technique are shown by M-File Controlling block of Simulink Library in Mat Lab Control tool box.