Search Results (87)

This study aims to address the problem that traditional helical gears generate significant axial forces during transmission and innovatively proposes a design scheme of double helical face gears (DHFG). An accurate mathematical model of the tooth surface is established using spatial meshing theory and coordinate transformation. A systematic investigation using the orthogonal test method is then conducted to analyze the influence of key parameters, such as the pinion tooth number, transmission ratio, and helix angle, on gear performance. The finite element analysis results show that the overlap degree of this double helical tooth surface gear pair in actual transmission can reach 2–3, demonstrating excellent transmission smoothness. More importantly, its unique symmetrical tooth surface structure successfully achieves the self-balancing effect of axial force. Simulation verification shows that the axial force is reduced by approximately 70% compared to traditional helical tooth surface gears, significantly reducing the load on the bearing. Finally, the prototype gear is successfully trial-produced through a five-axis machining center. Experimental tests confirmed that the contact impressions are highly consistent with the simulation results, verifying the feasibility of the design theory and manufacturing process. Full article

We present a case of unexpected proximal displacement of an intramedullary pin (IMP) during plate–rod repair of a femoral fracture caused by minimally invasive plate osteosynthesis (MIPO), requiring immediate revision. Implant retrieval analysis and ex vivo modelling were performed to characterise the technique failure mode. The case details are reported. Implant retrieval analysis consisted of stereo zoom microscopic examination of the retrieved IMP. Wear patterns formed by conflict with a 2.8 mm, two-fluted surgical drill bit and a 3.5 mm AO locking screw were replicated using a simple paper impression model. The mechanism of pin movement was replicated in a benchtop laminated polyurethane foam block model, and wear patterns produced during drilling and screw insertion were characterised using stereo zoom. The wear pattern visible on the retrieved IMP suggested axial displacement caused by a rack-and-pinion-like mechanism, enacted by contact with either the drill bit or locking screws during placement of the repair construct. Significant axial displacement of the IMP due to conflict with screws during construct placement is possible during the placement of plate–rod fixation. Surgeons should confirm implant positioning if implant conflict is recognised intra-operatively. Full article

To extend the time between the overhauls of helicopters, a novel collaborative methodology that takes into account uncertain misalignment errors by considering the shape and performance of the gear is built. Firstly, the digital characteristics of contact patterns, such as the reference point and direction angle, are extracted. Secondly, an optimization model calculates the equivalent misalignment by minimizing deviations in the reference point and direction angle between two contact patterns. This equivalent misalignment accounts for uncertainty misalignment errors introduced by complex gear support deformation. Thirdly, the ease-off is utilized to derive the pinion target surface that can sustain meshing performance under an equivalent misalignment, similar to the original gear in real conditions. This way it integrates with the optimization theory for flank reconstruction to redesign the pinion surface. Simulations reveal that the critical digital characteristics of the contact path on the original gear under the equivalent misalignment mirror those of the original gear in real conditions. Moreover, the surface parameters of the redesigned pinion result in an identical surface under a different equivalent misalignment, maintaining similar contact and dynamic performance. This proposed collaborative design approach, considering the shape and performance while accounting for uncertain misalignment errors through ease-off, greatly improves the gear transmission behavior. Full article

Polymer worm gears are increasingly utilized in electric power steering (EPS) systems due to their favorable manufacturing features and performance. Ensuring consistent mechanical properties under various operating conditions is critical for steering reliability throughout a vehicle’s lifespan. This study investigates the durability of injection-molded polyamide 66 worm gears within a Pinion-EPS configuration, where torque from the assist motor is transmitted through a worm–worm gear set to the rack and ultimately to the vehicle wheels. Given the complexity of steering maneuvers and the absence of mechanical integrity in steer-by-wire systems, durability testing becomes essential to understand if the considered worm gear for a certain steering system application provides safety and the needed performance within a specified product service life. This paper compares multiple testing methodologies. Traditional approaches, such as maximum torque and rotational speed, prove insufficient for comprehensive durability assessment, especially considering the thermal sensitivity of polymer materials. The findings highlight the limitations of conventional testing methods and emphasize the need for application-specific testing methods that reflect real-world boundary conditions. This research contributes to the development of more accurate and reliable evaluation techniques for polymer gear components in modern EPS systems, with implications for both conventional and autonomous vehicle platforms. Full article

To rapidly evaluate the meshing performance of manufactured face-gear drives, this study proposes an efficiency-optimized tooth contact analysis (TCA) method for measured gear flanks based on Ease-off surface. Initially, mathematical models of the pinion and face-gear tooth flanks are established. A TCA framework leveraging conjugate relationships and Ease-off surfaces is then developed. Subsequently, measured flank data are fitted into continuous error surfaces through Bicubic spline fitting, enabling full-tooth flank error mapping. These error distributions are integrated into the Ease-off surface model to simulate realistic meshing behavior, extracting critical performance metrics including contact paths and transmission errors. Validation through computational TCA, finite element analysis (FEA), and rolling tests confirm the method’s accuracy and computational efficiency. Full article

Wireless power transfer (WPT) technology offers a convenient, efficient, and environmentally robust power supply solution for rack-and-pinion modules. For WPT systems in such modules where the transmitter coil is a long rail, increasing the transmitter coil turns to enhance mutual inductance leads to issues like high cost, low efficiency, and installation difficulties. This paper introduces a relay resonator to strengthen system coupling and proposes a three-coil design scheme employing a single-turn long rail as the transmitter coil. The proposed all-detuned LCC-S-S topology exhibits constant output voltage (CV) and zero phase angle (ZPA) input characteristics while accounting for all cross-mutual inductances and coil resistances. The frequency detuning level of the relay resonator critically governs the system’s power transfer efficiency and directly determines the operational mode of the rectifier—either continuous conduction mode (CCM) or discontinuous conduction mode (DCM). To maximize system efficiency, the optimal detuning frequency of the relay coil is selected under CCM operation. Through optimized design of the three-coil parameters, the final prototype achieves an output power of 106.743 W and an efficiency of 90.865% when integrated with a 1200 mm single-turn long-rail transmitter coil. Full article

Digital Twins (DTs) have become essential tools for the design, diagnostics, and prognostics of mechanical systems. In gearbox applications, DTs are often built using physics-based simulations guided by ISO standards. However, standards-based approaches may suffer from complexity, licensing limitations, and computational costs. The concept of symmetry is inherent in gear mechanisms, both in geometry and in operational conditions, yet practical applications often face asymmetric load distributions, misalignments, and asymmetric and symmetric nonlinear behaviors. In this study, we propose a hybrid method that integrates data-driven modeling with standard-based simulation to develop efficient and accurate digital twins for gear transmission systems. A digital twin of a spur gear transmission is generated using KISSsoft^®, employing ISO standards to compute safety factors across varied geometries and load conditions. An automated MATLAB-KISSsoft^® (COM-interface) enables large-scale data generation by systematically varying key input parameters such as torque, pinion speed, and center distance. This dataset is then used to train a neural network (NN) capable of predicting safety factors, with hyperparameter optimization improving the model’s predictive accuracy. Among the tested NN architectures, the model with a single hidden layer yielded the best performance, achieving maximum prediction errors below 0.01 for root and flank safety factors. More complex failure modes such as scuffing and micropitting exhibited higher maximum errors of 0.0833 and 0.0596, respectively, indicating areas for potential model refinement. Comparative analysis shows strong agreement between the NN outputs and KISSsoft^® results, especially for root and flank safety factors. Performance is further validated through sensitivity analyses across seven cases, confirming the NN’s reliability as a surrogate model. This approach reduces simulation time while preserving accuracy, demonstrating the potential of neural networks to support real-time condition monitoring and predictive maintenance in gearbox systems. Full article

This paper presents a high-order model-based robust control strategy for a dual-motor road wheel actuating system in a steer-by-wire (SbW) architecture. The system consists of a belt-driven and a pinion-driven motor collaboratively actuating the road wheels through mechanically coupled dynamics. To accurately capture the interaction between actuators, structural compliance, and road disturbances, a four-degree-of-freedom (4DOF) lumped-parameter model is developed. Leveraging this high-order dynamic model, a composite control framework is proposed, integrating feedforward model inversion, pole-zero feedback compensation, and a disturbance observer (DOB) to ensure precise trajectory tracking and disturbance rejection. High-fidelity co-simulations in MATLAB/Simulink and Siemens Amesim validate the effectiveness of the proposed control under various steering scenarios, including step and sine-sweep inputs. Compared to conventional low-order control methods, the proposed approach significantly reduces tracking error and demonstrates enhanced robustness and disturbance attenuation. These results highlight the critical role of high-order modeling in the precision control of dual-motor SbW systems and suggest its applicability in real-time, safety-critical vehicle steering applications. Full article

Optimizing manufacturing processes to reduce scrap and enhance process stability presents significant challenges, particularly when multiple conflicting objectives must be addressed concurrently. As the number of objectives increases, the complexity of the optimization task escalates. This difficulty is further intensified in online optimization scenarios, where optimal parameter settings must be delivered in real time within active production environments. In this work, we propose a reinforcement learning-based framework for the multi-objective optimization of manufacturing parameters, demonstrated through a case study on pinion gear manufacturing. The framework utilizes the Multi-Objective Maximum a Posteriori Optimization (MO-MPO) algorithm to train a reinforcement learning agent. A high-fidelity simulation of the pinion manufacturing process is constructed in Simufact, serving both data generation and validation purposes. The agent’s performance is assessed using a hold-out test set along with additional simulations of the physical process. To ensure the generalizability of the approach, further validation is performed using open-source manufacturing datasets and synthetically generated data. The results demonstrate the feasibility of the proposed method for real-time industrial deployment. Moreover, Pareto-optimality is verified via half-space analysis, emphasizing the framework’s effectiveness in managing trade-offs among competing objectives. Full article

This study presents the design and experimental testing of a two-degrees-of-freedom (2DOF) elbow prosthesis prototype designed to replicate the movement patterns of a native or normal human elbow. Two methods of the control of the prosthesis, namely, the proportional–integral–derivative method (PID; a well-established method) and a combination of sliding mode control with a time base generator strategy (SMC + TBG; an advanced method), were compared on the basis of various performance metrics of the prosthesis, as obtained in laboratory tests. Among these metrics were the angular displacement and velocity as a function of time. The mechanical design combined 3D-printed components with custom-designed joints, featuring a worm gear transmission with a crown gear for flexion–extension, enhanced by torsional springs, and a pinion gear with a crown gear for pronation–supination and control. Sensors for voltage and current data acquisition enabled real-time monitoring and control. The prosthesis was tested in the laboratory with a range of motion of 100–120° for flexion–extension, 50° for supination, and 75° for pronation, demonstrating the adaptability of the actuators and validating their autonomy through battery-powered operation. The results showed that control using SMC + TBG resulted in biomimetic patterns for angular displacement and angular velocity of the prosthesis, whereas control using PID did not. Thus, the prosthesis with control provided using an SMC + TBG strategy may have been promised for use by people who have undergone transhumeral amputation. Full article

With frequent interactions between social media platforms, the dissemination of information and the interaction of opinions on the internet have become increasingly complex and diverse. This increase in information complexity not only affects the formation of public opinion but may also exacerbate the spread of diseases. Based on multilayer complex networks and combined with the Deffuant-I model, this paper explores the dual impact of information complexity and individual characteristics on both information and disease propagation. Through systematic simulation experiments, this paper analyzes the mechanisms of information complexity, individual compromise, and cognitive ability in the evolution of propagation. This study shows that the interactive effects of individual characteristics and information complexity have a significant impact on disease spread. This research not only provides a new theoretical perspective for understanding complex information dissemination but also offers valuable insights for public policymakers in promoting social harmony and addressing public health emergencies. Full article

Gear condition monitoring is predominantly executed through the utilization of acceleration sensors positioned on the housing. However, recent advancements have identified measuring the instantaneous angular speed as a compelling alternative as it shortens the transmission path and therefore provides high-quality rotational angle information that can be used to increase damage prediction accuracy, particularly under transient operating conditions. Additionally, there are a variety of methodologies for integrating sensors into gears, which underscores the necessity for high-quality condition data. However, it should be noted that a significant amount of effort is required to successfully integrate these sensors into the rotating system. This publication uses a gear wheel sensor that employs the gear itself as a material measure to acquire rotational angle data and to deduce the damage condition. A magnetoresistive sensor is integrated into the gearbox housing radially facing a ferromagnetic gear and measures the rotational angle by the gear teeth. Various artificial tooth flank damages are applied to the pinion. The rotational angle is measured with the gear sensor, and the damage state is classified with a random forest classifier using established evaluations in the time and frequency domains. The tests are conducted under stationary operating conditions at an array of speed and torque levels. Additionally, they are performed under transient operating conditions, employing speed ramps at constant torque. The results of the classification are evaluated by means of classification accuracy and confusion matrices and compared with those obtained via a classic encoder at the pinion shaft and an acceleration sensor at the gearbox housing. Full article

This study proposes a novel expandable spinal cage to maximize the effectiveness of spinal fusion surgery in the treatment of lumbar disk disorders and aims to verify its mechanical stability through finite element method (FEM) analysis and mechanical testing. To address the limitations of existing cages, which do not provide sufficient height and angle expansion and have constraints in independently adjusting height and angle with continuous fine-tuning, this study introduces a new linkage mechanism. This design enables precise spinal alignment restoration tailored to the individual anatomical characteristics of patients, even in minimally invasive surgical environments, distinguishing itself from traditional rack-and-pinion or wedge-based designs. The results of FEM analysis and static load testing demonstrated a high correlation between the predicted yield locations in FEM analysis and actual test results. Furthermore, the compression and compression–shear load tests confirmed that the proposed cage achieved an ultimate load exceeding the lowest fifth percentile of FDA-approved products, meeting clinical requirements. The proposed expandable spinal cage offers significant improvements over existing products and has the potential to evolve into a safer and more effective spinal fusion device through further dynamic fatigue testing and clinical studies to assess long-term durability and practical applicability. Full article

Skiving is an efficient method for manufacturing face gears, but theoretical machining errors may occur when face gears designed for shaping or grinding are processed by skiving. This study presents a face gear directly designed for the skiving process, eliminating theoretical machining errors. Additionally, a new design approach for the cylindrical gear is proposed to pair with this face gear. The tooth surface models of both the cylindrical pinion and face gear are established. For the pinion, surface modifications are applied in both profile and longitudinal directions, while the face gear’s tooth surface model is tailored for the skiving process to avoid theoretical machining errors. The contact performance, including transmission error, contact stress, and contact pattern, is evaluated through Tooth Contact Analysis (TCA). An optimization model is developed to identify the optimal cylindrical gear tooth surface parameters, targeting improved contact performance. The proposed method is validated by a case study, which shows that the optimized face gear transmission results in lower maximum contact stress and reduced transmission error amplitude. Full article

This paper investigates the geometric interchangeability and dimensional precision of parts fabricated using Fused Deposition Modeling (FDM), with a focus on gear manufacturing. By employing a substrate and two spur gears as test components, critical process parameters, including layer thickness, extrusion speed, and print temperature, were optimized to achieve enhanced accuracy. Geometric and dimensional tolerances such as straightness, roundness, and surface roughness were systematically evaluated using advanced metrological techniques. The results indicate that larger components demonstrate higher precision, with deviations for large and pinion gears ranging between −0.045 and 0.060 mm, and −0.150 and 0.078 mm, respectively. Analysis reveals that the anisotropic nature of the FDM process and thermal shrinkage significantly impact accuracy, particularly in smaller features. Residual stress analysis reveals that smaller components formed via FDM exhibit higher stress concentrations and dimensional deviations due to voids and uneven thermal contraction, whereas larger components and flat substrates achieve better stress distribution and precision. The findings suggest that reducing material shrinkage coefficients and optimizing process parameters can enhance part quality, achieving dimensional tolerances within ±0.1 mm and geometric consistency suitable for practical applications. This research highlights the potential of FDM for precision manufacturing and provides insights into improving its performance for high-demand industrial applications. Full article