Rotational Torque Research Articles

Insight into drilling performance parameters for in-situ detection of lithological transition

In order to examine the rock dependence on drilling performance parameters, such as torque and rate of penetration (ROP), we conducted laboratory drilling experiments using mafic and ultramafic rocks from the Oman ophiolite and the Horoman Complex. Serpentinized peridotite shows approximately twice the ROP (dry conditions: 2.95 ~ 3.85, wet conditions: 8.25 ~ 10.3 × 10−5 m/min) compared to that of peridotite and mafic samples (dry conditions: 4.75 ~ 6.90, wet conditions: 14.5 ~ 18.3 × 10−5 m/min) under both dry and wet conditions. This result is likely due to the reduction in fracture strength associated with serpentinization. We compared the laboratory results of drilling parameters with in situ data obtained from IODP Expedition 360 drilling of gabbro and Expedition 399 drilling of serpentinized peridotite, using the equivalent strength method to normalize ROP to the given rotation rate and torque. The calculation results show that the normalized ROP for the serpentinized peridotite formation was systematically higher than that for the gabbro layer, which is in agreement with our experimental results. We propose that the in situ drilling performance parameters can be used to detect the lithological transitions, such as serpentinite.

Experimental and Simulation Investigation of J-Shaped and Kammtail Virtual Airfoils in Small-Scale Horizontal Axis Wind Turbines

Abstract In this work, the performance of new wind blade designs for small-scale horizontal axis wind turbines (HAWTs) was studied and compared with the performance of a baseline design. Three J-shaped pressure-side truncation ratios (1/3, 1/2, and 2/3) and two Kammtail Virtual Foil (KVF) truncation ratios (1/8 and 1/4) were studied. The baseline design was experimentally investigated. Output power was measured using a digital rotary torque sensor at three different wind speeds. Tip speed ratio (TSR) was calculated after measuring each wind speed's free-rotating revolutions per minute (RPM). Three wind speeds and experimental TSRs were used in three-dimensional simulations to capture the performances of the proposed cases and compare them with the baseline. The simulation investigation was carried out for lab-scale and scaled cases. The three-dimensional study found that the J-shaped blades enhanced the performance of the HAWTs for both lab-scale and scaled cases. J-shaped blades with a 1/3 opening ratio yielded an average power coefficient enhancement of around 1.56% and 4.16% for lab-scale and scaled cases, respectively. J-shaped blades with a 1/2 opening ratio yielded an average power coefficient enhancement of around 1.15% and 4.23% for lab-scale and scaled cases, respectively. On the other hand, J-shaped blades with a 2/3 opening ratio yielded an average power coefficient enhancement of around −0.12% and 2.54% for lab-scale and scaled cases, respectively. Furthermore, it was found that the KVF blades diminished the performance for both lab-scale and scaled cases.

Finite element analysis and experimental verifications of low-speed rotor torque of magnetic-geared motor with permanent magnets only in stator

We propose a magnetic-geared motor with controllable step-out torque. The operational principle which controls the step-out torque using DC currents is described. The controllable step-out torque characteristics are computed using finite element method. In addition, the load characteristics under vector control are also computed using finite element method. Two inherent characteristics are observed in this analysis result. One is that this magnetic-geared motor can generate the torque more than the step-out torque. The other is that the phase angle difference between the rotors when both rotors step out is around 30 deg. In this paper, the mechanism of these inherent characteristics is investigated by finite element method, and these inherent characteristics are verified by carrying out measurements on a prototype.

Peak hip external rotation torque and single-rater reliability is influenced by measurement position in the ISOMED2000

Measurement of hip external rotation strength (ERS) is important for preventive and rehabilitative purposes. ERS can be measured in 3 different positions in the isokinetic dynamometer ISOMED2000. However, it is not clear whether these measurement positions effect ERS nor if these positions are reliable in the ISOMED2000. Hence, the purpose of this study was to compare ERS in these positions, the reliability and the agreement. A cross-sectional design was conducted to compare measurement positions and a test–retest design to assess intra-rater reliability and agreement. Twenty-four healthy, physically active athletes participated in the study. Peak isometric torque was measured in the ISOMED in prone, supine, and side-lying position across two sessions on one day. Differences between positions were evaluated with the Wilcoxon-signed-rank test and cliff’s delta. Reliability was assessed via intraclass correlation. Agreement was determined using the standard error of measurement (SEM), minimal detectable change (MDC), and Bland-Altman analysis (BAA). Results indicated a significant influence of measurement position on ERS (p < 0.001) with high effect sizes (>0.74). Reliability and agreement were high in all positions, but highest for the side-lying position (ICC = 0.90 [0.78, 0.96]; SEM = 0.08; MDC = 0.23; BAA_bias = 3.4 %, BAA_loA = 37 %). There were only poor to moderate correlations between measurement positions. These findings suggest that measurement position significantly affects ERS. Furthermore, the effect varies across individuals indicating that normative values cannot be used interchangeably or be adapted across positions. In diagnostic testing ERS should be measured in the same position, but preferably in the side-lying position.

Compressive force and valgus torque are the predominant applied loads during the pivot shift exam: An in vitro study.

Despite the clinical utility of the pivot shift exam, the requisite applied forces and torques to elicit a pivot shift remain unclear. The purposes of this study are (1) to identify the greatest forces and torques applied to the knee during the pivot shift exam and (2) to evaluate if the applied loads differ among experienced surgeons. Three cadaveric hemipelvis-to-toe specimens (ages 53, 36 and 31 years; two males and one female) with no history of knee or hip injury were utilized. The experimental setup consisted of securing the hemipelvis to a mounting frame via an external fixator to simulate patient positioning during the clinical exam. The hemipelvis, femur, and tibia were spatially tracked by motion capture and the applied loads were measured using a 6-axis force-torque sensor. After sectioning the anterior cruciate ligament (ACL), three board-certified sports medicine surgeons then performed the pivot shift exam on each specimen utilizing their preferred technique. Forces (compression-distraction, anterior-posterior, and medial-lateral) and torques (varus-valgus, internal-external rotation, and flexion-extension) applied to the knee joint immediately preceding the reduction of the proximal lateral tibia during each pivot shift exam were calculated. Compression was the largest applied force averaging 95 N ± 15 N for all surgeons and knees, which was at least 4.5 times greater, on average, than the applied anterior and applied medial tibial forces (p < 0.0001). Valgus was the largest of the three applied torques, averaging 8.5 ± 2.1 Nm. Internal rotation torque was 3.7 times less, on average, than the applied valgus torque (p < 0.0001). Each surgeon applied compressive force. However, anterior force was more variable among surgeons, with one of the three surgeons applying minimal anterior force (p ≤ 0.024). The magnitude of applied torques was similar among examiners (n.s). Compressive force and valgus torque were the predominant applied loads during the pivot shift exam. A lower magnitude of internal rotation torque was also applied. The anterior force was not consistently applied among examiners. These data can better inform clinical, cadaveric, and computational studies utilizing the pivot shift exam to assess knee biomechanics and can be used to educate trainees in conducting this complex manoeuvre. An in vitro biomechanic study.

Effect of Acetabular Labral Tear Orientation on Hip Joint Kinematics: A Comparison of Radial Tears, Chondrolabral Junction Tears and Complex Tears in Cadaveric Hips.

Acetabular labral tear morphology or orientation may influence hip stability. A radial tear of the acetabular labrum would result in greater rotational and translational motion compared with a chondrolabral separation. Controlled laboratory study. Included were 12 unpaired nonarthritic hip specimens, none of which had capsular laxity (8 male; mean age, 34.5 years). The specimens were stripped of all soft tissue except the hip capsule and labrum and, then potted using a custom jig. In 6 specimens, a 1-cm anterosuperior separation of the labrum from the acetabular rim (chondrolabral junction tear; CLJT) was created. In the other 6 specimens, a radial tear was created at the anterosuperior acetabulum. Subsequently, a complex labral tear was created in all specimens by adding a radial tear to the CLJT specimens and vice versa. The specimens were mounted on a load frame, and the femoral head displacement in the neutral and hyperextended positions was recorded at 5 N·m of internal/external rotation (IR/ER) torque and at 50 N of superior-inferior (S-I), anterior-posterior (A-P), and medial-lateral (M-L) force. Testing occurred at 0° extension and at maximal extension both before and after initial labral tear creation and again after creation of the complex labral tear. Before testing (intact state), the joint was vented to remove the effect of intra-articular pressure difference between the intact capsule and after capsulotomy for labral tear creation. The t test was used to calculate group differences by each range of motion measure (IR/ER and S-I, A-P, and M-L translations) for neutral and hyperextension. Neither the radial labral injury nor the CLJT produced differences from the vented state in any combination of hip position or plane of motion. The complex labral tear showed increased IR/ER rotation at maximal hip extension. There was no difference between CLJT and radial labral tear in any combination of hip position or plane of motion. A simple labral tear did not affect hip joint stability when the capsule was intact, and no capsular laxity was present. A complex labral tear caused increased rotational laxity at maximal extension. Capsular laxity or a complex labral tear may be a prerequisite for labral injury to cause increased hip joint motion and/or translation. Study findings suggest that labral tears in the absence of capsular laxity may not play a role in producing microinstability by increasing motion or translation.

Lateralization has minimal biomechanical impact on tuberosity fixation with the use of a stem-based repair and a 135o humeral implant in reverse shoulder arthroplasty for four-part proximal humerus fracture

IntroductionLateralization in reverse shoulder arthroplasty (RSA) has many proven and potential benefits. Concern over the increase in tension on the tuberosities imparted by glenoid lateralization and the subsequent effect on tuberosity healing may limit its use in the setting of RSA performed for fracture. This study evaluated whether glenoid lateralization increased tuberosity fracture gapping in a biomechanical model of a 4-part proximal humerus fracture with a stem-based tuberosity repair. We hypothesized that increased lateralization would increase fracture gapping. Materials and MethodsEight cadaveric shoulders (mean age, 62 +/- 2.4 years; range 52-70 years) were tested with a custom testing system that permits loading of rotator cuff muscles and humerothoracic muscles. A four-part proximal humerus fracture was simulated and then repaired with a stem-based tuberosity repair. The repaired tuberosities were cycled in internal and external rotation with 1.1Nm torque at 2 mm and 6 mm of glenoid lateralization. For the 6mm lateralization RSA, the torque was then increased to reach the range of motion values achieved with the 2mm lateralized RSA and cycled 10 times, followed by doubling the torque values for 10 cycles. Range of motion, muscle length and fracture gapping were assessed at 2 mm and 6 mm of glenoid lateralization. ResultsInternal rotation and total ROM demonstrated a significant decrease in the 6 mm RSA when compared to the 2 mm RSA (p < 0.05). The 6 mm lateralized RSA significantly increased rotator cuff muscle lengths when compared to the 2 mm lateralized RSA condition except for infraspinatus by an average of 2.7 ± 1.9mm (p < 0.05). There was no significant gapping of the proximal fracture for any condition. There was a significant increase in the gapping of the distal fracture gap in the 6 mm lateralized component condition only after 10 cycles of doubled rotational torque, which measured 1.9 ± 1.5mm (p = .031). DiscussionWe hypothesized that lateralization would increase fracture gapping. Fracture gapping did not occur proximally and only occurred at a slight amount distally after 10 cycles of doubled rotational torque. This may have implications on the choice of glenoid components when performing a RSA for fracture.

Design and Stability Analysis of Six-Degree-of-Freedom Hydro-Pneumatic Spring Wheel-Leg

Traditional hydro-pneumatic spring suspensions are limited to a single vertical degree of freedom, which cannot accommodate the significant technological changes introduced by the new in-wheel motor drive mode. Integrating the motor into the vehicle’s hub creates a direct motor drive mode, replacing the traditional engine–transmission–drive shaft configuration. Together with the dual in-wheel motor wheelset structure, this setup can achieve both drive and differential steering functions. In this study, we designed a six-arm suspension wheel-leg device based on hydro-pneumatic springs, and its structural composition and functional characteristics are presented herein. The external single-chamber hydro-pneumatic springs used in the six-arm structure suspension were analyzed and mathematically modeled, and the nonlinear characteristic curves of the springs were derived. To overcome the instability caused by inconsistent extension lengths of the hydro-pneumatic springs during horizontal steering, the spring correction force, horizontal rotational torque, consistency, and stiffness of the six-degree-of-freedom hydro-pneumatic spring wheel-leg device were analyzed. Finally, with the auxiliary action of tension springs, the rotational torque of the hydro-pneumatic springs and the tension resistance torque of the tension spring counterbalanced each other, keeping the resultant torque on the wheelset at approximately 0 N∙m. The results suggest that the proposed device has excellent self-stabilizing performance and meets the requirements for straight-line driving and differential steering applications. This device provides a new approach for the drive mode and suspension design of the dual in-wheel motor wheelset.

Design and optimization of squeeze-shear mode MR brake with multi-fluid flow channels based on multi-objective sooty tern optimization algorithm

Abstract Aiming at the deficiency of magnetic field utilization rate and the mass–torque ratio of magnetorheological fluid brake (MRB), a novel MRB is proposed in this paper. Initially, a squeeze-shear mode MRB with multi-fluid flow channels (S-MRB) is designed and its structure and working principle are described. Based on the analysis of the magnetic circuit, mathematical models are established to describe the rotary torque of the S-MRB. Furthermore, COMSOL software is carried out to model and simulate the electromagnetic field of the S-MRB, which verified the rationality of structure design. Then, with the braking torque and mass of the S-MRB as objective function, multi-objective optimization algorithm is adopted to optimize the structural parameters of the S-MRB. The optimization results show that the braking torque is increased by 25.34% and the mass of the MRB is decreased by 2.7%. Finally, a MRB braking performance test platform is established, and the effectiveness and superiority of the S-MRB are verified by braking torque dynamic response characteristic experiments.

Enhancing machinability in free-cutting duplex brass alloys: Isotropic blocky α phase formation via optimized hot extrusion processing

Despite the active utilization of duplex brass alloys in the electronics and automotive industries, optimizing thermomechanical treatment conditions for achieving excellent machinability remains a subject of ongoing debate. In this study, to establish a strategy to achieve enhanced machinability via industrial-scale direct hot extrusion processing, we systematically investigated the effect of hot extrusion processing conditions on microstructural evolution, mechanical properties, and machinability of duplex brass alloys. In particular, the yield strength was effectively interpreted through the extended Hall-Petch relationship, and the machinability was further elucidated through the evaluation of rotational torque during the drilling test as well as the precise analysis of segmented chips produced in the drilling test. As a result, our microstructural analysis of the as-cast Cu58Zn39Pb3 alloy revealed that the cooling process during industrial-scale casting inevitably results in the formation of the Widmanstätten structured α phase and the heterogeneous dispersion of Pb particles. In contrast, 670 ℃ extruded lower part and 730 ℃ extrudates, which were extruded in the single β region that caused complete dynamic recrystallization behavior, exhibited a uniform and isotropic blocky α structure and uniformly redistributed Pb particles, ultimately leading to superior mechanical properties and machinability. Notably, our findings suggest that achieving an isotropic blocky α structure can be attained at temperatures up to 100 ℃ below the β-transus temperature by optimizing extrusion pressure conditions. This approach offers an efficient methodology for minimizing defects caused by high-temperature extrusion, such as surface oxidation and hot shortness cracking, while simultaneously minimizing processing costs.

Numerical Analysis of A Two-Phase Turbine: A Comparative Study Between Barotropic and Mixture Models

Abstract Two-phase turbines offer the potential to significantly enhance the performance of power generation and refrigeration systems. However, their development has been hindered by comparatively lower efficiencies resulting from additional loss mechanisms absent in single-phase turbines. To date, most multiphase CFD studies on turbomachinery have focused on condensation in the final stages of steam turbines, and on cavitation in hydraulic pumps and turbines. These applications, however, are not representative of the conditions in two-phase turbines, where a liquid-dominated mixture undergoes a large expansion ratio, leading to a significant increase in the gas phase volume fraction throughout the entire flow. This paper aims to identify a suitable modeling methodology for two-phase turbines. Our evaluation is centered around two models: the mixture model and the barotropic model. The validity and accuracy of these two modeling approaches is assessed using existing experimental data from a single-stage impulse turbine operating with several mixtures of water and nitrogen as working fluid. The results indicate that both the mixture and barotropic models are consistent and accurately predict the nozzle mass flow rate, yet, both models systematically overpredict the nozzle exit velocity and rotor torque. Adding correction terms for windage and unsteady pumping losses significantly improves the torque predictions, bringing them within the uncertainty range of the experimental data. In addition, refining the models to account for the effect of slip presents a promising avenue to enhance the prediction of nozzle exit velocity and overall performance of two-phase turbines.

Effect of carbodiimides on the compatibility and hydrolytic behavior of PLA/PBAT blends

Blends of polylactic acid (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) have great potential to replace conventional polyolefin and polyester materials. However, poor compatibility and fast degradation rate limit its development. In this paper, the effects of two monomer-type carbodiimides and one polymerized carbodiimide on the crystalline, thermal stability, hydrolysis properties, and mechanical properties of PLA/PBAT blends are investigated by Fourier transform infrared spectroscopy, scanning electron microscope, differential scanning calorimetry, thermogravimetric analysis, gel permeation chromatography, melt mass-flow rate, terminal carboxyl content, tensile properties, and rotational torque. It is found that all the three carbodiimide additives can improve the compatibility and enhance the mechanical, processing, and thermal stability properties of PLA/PBAT blends except for their reduced crystallization performance. Moreover, regarding the hydrolysis properties, the two monomeric carbodiimides exhibit little effect on the hydrolysis of PLA/PBAT blends, even accelerating the degradation rate under alkaline conditions. However, the antihydrolysis effect of polycarbodiimide is remarkable, which effectively improves the compatibility and antihydrolysis properties of PLA/PBAT blends.

Enhancing Savonius Rotor Performance with Zigzag in Concave Surface-CFD Investigation

Savonius, a type of vertical-axis wind turbine (VAWT), is suitable as an appropriate small-scale energy conversion apparatus for regions with relatively low wind speeds, such as Indonesia; however, it exhibits sub-optimal efficiency. One potential approach to improving the efficiency of Savonius turbines is to increase the drag force on the concave surface of the blades. In this case, the dissimilarity in the forces experienced by the two blades can be increased, resulting in a corresponding increase in torque. This investigation aims to assess and compare the power coefficient (Cp), torque and drag coefficient (Cd) of the conventional Savonius rotor with the zigzag pattern implemented in the middle area of the concave surface of the blades at low wind speeds. The efficiency can be achieved by implementing the k-ω shear stress transfer (SST) turbulent model and 3D computational fluid dynamics simulation at tip speed ratio (λ) 0.4-1 with a velocity inlet of 4, 5, and 6 m/s. The study results show that using the zigzag pattern on the concave surface led to an 18.8% boosted in Cp of at λ = 0.8 and an inlet velocity (U) = 5 m/s compared to the standard Savonius rotor model. In this case, the efficiency of the Savonius wind turbine may be enhanced by incorporating a zigzag pattern in the middle of the concave surface of the Savonius rotor.

Influence of Continuous Rotation and Optimal Torque Reverse Kinematics on the Cyclic Fatigue Strength of Endodontic NiTi Clockwise Cutting Rotary Instruments.

Objectives: The objective of the present study was to evaluate the cyclic fatigue strength of clockwise cutting rotary endodontic instruments when subjected to two different kinematics: continuous clockwise rotation and clockwise reciprocation movement under optimum torque reverse (OTR) motion. Methods: New ProTaper Next X1 (n = 20) and X2 (n = 20) instruments were randomly divided into two subgroups (n = 10) based on kinematics (continuous rotation or OTR). The specimens were tested using a custom-made device with a non-tapered stainless-steel artificial canal measuring 19 mm in length, featuring a 6 mm radius and an 86-degree curvature. All instruments were tested with a lubricant at room temperature until a fracture occurred. The time to fracture and the length of the separated fragment were recorded. Subsequently, the fractured instruments were inspected under a scanning electron microscope for signs of cyclic fatigue failure, plastic deformation, and/or crack propagation. The subgroup comparisons for time to fracture and instrument length were performed using the independent samples t-test, with the level of statistical significance set at 0.05. Results: When using OTR movement, the ProTaper Next X1 increased the time to fracture from 52.9 to 125.8 s (p < 0.001), while the ProTaper Next X2 increased from 45.4 to 66.0 s (p < 0.001). No subgroup exhibited plastic deformations, but both showed dimpling marks indicative of cyclic fatigue as the primary mode of failure. Additionally, OTR movement resulted in more metal alloy microcracks. Conclusions: The use of OTR motion extended the lifespan of the tested instruments and resulted in a higher number of metal microcracks. This suggests that OTR motion helped to distribute the mechanical stress more evenly across the instrument, thereby relieving localized tension. As a result, it delayed the formation of a single catastrophic crack, enhancing the overall performance of the instruments during the experimental procedures.

Numerical simulation investigation on aerodynamic characteristics of rotor in plateau environment

To investigate the impact of high-altitude environments on helicopter rotor aerodynamic characteristics, this study developed a computational model that integrates CFD, BP neural networks, and the free wake method. The accuracy of the model was validated through wind tunnel experiments and comparisons with CFD results. Using this model, the effects of altitude and temperature at high altitudes on rotor aerodynamic characteristics during hover and forward flight were studied. The results indicate that with constant temperature, rotor thrust significantly decreases as altitude increases, primarily due to reduced air density. As altitude rises with unchanged temperature, the decrease in air density directly affects the lift and thrust generated by the rotor, leading to a decline in hover performance. Furthermore, the study found that rotor aerodynamic coefficients do not vary significantly across different altitudes. Further analysis suggests this stability is due to the high Reynolds number in the calculated state. In the high Reynolds number range, changes in Reynolds number have minimal impact on aerodynamic coefficients, resulting in relatively stable aerodynamic performance across varying altitudes. At a constant altitude, lower temperatures lead to slight increases in rotor thrust and torque, while the thrust coefficient and power coefficient remain almost unaffected. This phenomenon is attributed to changes in air density and viscosity caused by the lower temperatures. The increase in air density positively impacts thrust and torque, while the reduction in air viscosity decreases the rotor's surface frictional resistance. This partially offsets the increase in lift and drag caused by the higher air density, leading to negligible changes in thrust and power coefficients.

Performance improvement of Grid-Connected Wind Energy Conversion System through Definite Time Horizon Control and MPPT based on Adaptive Observers

This research work investigates the implementation of Definite Time Horizon Control (DTHC) through an observer in a grid-connected Wind Energy Conversion System (WECS) equipped with a Permanent Magnet Synchronous Generator (PMSG). The main objective is to achieve sensorless Maximum Power Point Tracking (MPPT). To achieve this goal, mechanical rotational speed and torque estimates are exploited from an adaptive nonlinear observer. In addition, this work explores how the DTHC improves on the MPPT technique, enabling faster and more accurate tracking of the maximum power point. The proposed controller, unlike traditional non-linear controllers, rapidly stabilizes the WECS, tracking reference trajectories in a short, pre-determined period of time. Indeed, it demonstrates robustness in the face of unpredictable WECS parameters, adapting to variations thanks to a robust control design. Mathematical demonstrations of the defined time horizon stability and the resilience of the suggested WECS controllers are detailed in this investigation. This DTHC method improves rotor speed control, enabling more efficient sensorless MPPT. It contributes to improved WECS performance for following dynamic references and enhances adaptability against unpredictable parameters. In addition, it provides sophisticated control capabilities for the grid connected converter, improving the smoothness and efficiency of electrical energy injection.

The Influence of Reduced Frequency on H-VAWT Aerodynamic Performance and Flow Field Near Blades

Studies demonstrate that the reduced frequency k is influenced by the incoming wind speed U0 and the rotor speed n. As a dimensionless parameter, k characterizes the stability of the flow field, which is a critical factor affecting the performance of vertical-axis wind turbines (VAWTs). This paper investigates the impact of k on the performance of straight-blade vertical-axis wind turbines (H-VAWT). The findings indicate that 0.05 is the critical value of k. The same k results in a similar flow field structure, yet the performance changes vary with different U0. A decrease in n or an increase in U0 leads to an increase in the average value and fluctuation of k, which subsequently reduces the rotor rotation torque Cm and decreases the maximum wind energy utilization rate Cpmax. This reduction in Cpmax weakens the stability of the flow field. Additionally, the high-speed area of the blade’s trailing edge velocity trajectory at θ=0°, θ=120°, and θ=240° expands with increasing range. Velocity dissipation in the high-speed area of the trailing edge affects the stability of the flow field within the rotor.

Research on the efficiency analysis method of 9AT transmission planetary gear system based on power loss

As the core element of power transmission in Automatic Transmission (AT), the planetary gear system has advantages in the gear ratio range, load carrying capacity and transmission efficiency, and its transmission efficiency analysis is an important link in the design of automatic transmission.This paper proposes a method to analyze the transmission efficiency of planetary gear system of 9AT transmission considering power losses. Firstly, based on the hypergraph theory to establish the power transmission roadmap of each gear of the transmission (9AT) and the triangular hypergraph of the four-row planetary gear system, as well as the power flow model of the four-row planetary gear system without considering the power losses, and then the rotational speed, torque, and power change of each gear of the gear system are analyzed through the power spectrum. Secondly, a power flow model considering power losses and circulating power was established to analyze the influence law of different operating parameters (speed, torque, viscosity, gear meshing friction coefficient), and structural parameters (characteristic coefficients of each planetary row) on the transmission efficiency of the system. Finally, the equivalent planetary gear system transmission efficiency experimental bench considering losses is established to measure the transmission efficiency of the two-row planetary gear system at different speeds and torques, and the results of the experimental tests have the same trend with the theoretical calculations, which provides an analytical method to improve the transmission efficiency of the planetary gear system of the 9AT transmission.

Imitating pangolin scale structure for reducing adhesion and resistance of rotary tillage in wet-adhesive soil

The bionic design of soil-engaging components has recently received much attention in conservation tillage and is extremely important for reducing tillage resistance and increasing implement passability in wet-adhesive rice paddy soil. In this paper, to reduce adhesion and resistance of rotary tillage in wet-adhesive soil, a novel imitating pangolin scale structure is first proposed, and the bionic non-smooth surface parameters affecting the soil adhesion effect is clarified. Afterwards, based on the JKR attached Bonding contact model, an accurate discrete element interaction model of the designed rotary tillage blade -wet adhesive soil is established, and the effect of spindle speed, bump size and bump distance on the tillage resistance and soil disturbance is analyzed using the proposed model. Finally, the proposed imitating pangolin scale structure is optimized to improve the anti-adhesive and drag reduction properties using response surface method, furthermore, the corresponding model validation experiments and field tests are also conducted. Results reveal that the relative errors between the simulated and experimental values of the bionic blade rotary torque and soil adhesion mass are only respectively 4.4 % and 8.3 %. In addition, the optimal parameter combinations of anti-adhesion and drag reduction are also determined: the spindle speed is 180 rpm, the bump width is 10.6 mm and the bump distance is 17.9 mm, respectively, at the time, the effect of soil breaking of the designed blade is reduced by 9.95 % compared to that of the traditional blades but the effect of anti-adhesion and drag reduction is improved by 18.81 %.

Does Sagittal Alignment Matter? A Biomechanical Look at Pinning Pediatric Supracondylar Humerus Fractures.

Closed manipulation and percutaneous pinning is standard of care for displaced supracondylar humerus fractures, yet the optimal pin configuration, particularly in the sagittal plane, is not well defined. This study evaluates how sagittal plane pin variations affect construct strength biomechanically. One hundred synthetic pediatric humerus models were used to emulate supracondylar humerus fracture. The models were pinned using 4 different configurations uniformly divergent in the coronal plane with variations in the sagittal plane: (1) 2 diverging pins with the lateral pin anterior (n = 25), (2) 2 diverging pins with the lateral pin posterior (n = 25), (3) 2 parallel pins (n = 25), and (4) 3 parallel pins (n = 25). The models were tested under bending (flexion, extension, and varus) and rotational (internal and external) forces, measuring stiffness and torque. Statistical analyses identified significant differences across configurations. The 2-pin parallel configuration (9.68N/mm in extension, 8.76N/mm in flexion, 0.14 N-m/deg in internal rotation, and 0.14 N-m/deg in external rotation) performed similarly to the 3-pin parallel setup (10.77N/mm in extension, 7.78N/mm in flexion, 0.16 N-m/deg in internal rotation, and 0.14 N-m/deg in external rotation), with no significant differences in stiffness. In contrast, both parallel configurations significantly outperformed the 2-pin anterior (5.22N/mm in extension, 5.7N/mm in flexion, 0.11 N-m/deg in internal rotation and 0.10 N-m/deg in external rotation) and posterior (9.86N/mm in extension, 8.31N/mm in flexion, 0.12N-m/deg in internal rotation, and 0.11 N-m/deg in external rotation) configurations in resisting deformation. No notable disparities were observed in varus loading among any configurations. This study illuminates the sagittal plane's role in construct stability. It suggests that, when utilizing 2-pins, parallel configurations in the sagittal plane improve biomechanical stability. In addition, it suggests avoiding the lateral anterior pin configuration due to its biomechanical inferiority. Further research should assess ultimate strength and compare various 3-pin configurations to better delineate differences between 2-pin and 3-pin configurations regarding sagittal plane alignment. Level III-biomechanical study.