Gear Design Research Articles

A Machine Learning Technique for Deriving the Optimal Mesh Size of a Gizzard Shad (Konosirus punctatus) Gillnet

Gizzard shads are facing a continual decline in population, necessitating the implementation of selective gear design for effective resource management. This study aims to prevent the bycatch of young gizzard shads, a non-target fish species, and to derive mesh sizes appropriate for fishery management. Experimental fishing (n = 11) was conducted by manufacturing gillnet fishing gear with different mesh sizes (50.5, 55.1, 60.6, and 67.3 mm) in the coastal waters of the southern Gyeongsang Province. Two methods were employed to estimate the appropriate mesh size of the shad gillnet as follows: firstly, by analyzing the selectivity curve based on body length data; secondly, by developing a complex machine learning model considering biological and economic factors. Model 1 was constructed using mesh variables to classify the score groups. As a result of this study, the total length with a 0.5 gillnet selection ratio. which was estimated to be 179.3, 195.6, 215.1, and 238.9 mm for the 50.5, 55.1, 60.6, and 67.3 mm mesh sizes, respectively. In Model 1, a mesh size of 57.85 mm or less was determined as the most appropriate mesh size. Therefore, considering both biological and economic aspects, shad gillnets should have a mesh size in the 50.5 to 55.1 mm range.

Tooth profile design and meshing characteristics analysis of internal meshing gears based on variable center meshing line

A design method of internal meshing gear based on variable center meshing line (VCML) is presented in this paper. The meshing line is an arc line connecting the intersection of the indexing circle connecting the inner and outer gears and the intersection of the tooth top circle, and the center of the line of engagement freely slides on the vertical bisection line of the line connecting the two intersection points. The top tooth profile equation of internal and external gears is derived by rack equation. According to the normal method of gear profile, the equation of gear root meshing line is derived by using the tooth top profile equation of the gear. According to the principle of plane meshing, the root profile equation of gear is derived by using the root meshing line equation of gear. The tooth profile of VCML gear can be deduced quickly by adjusting the center position of the meshing line. The stress, meshing stiffness, transmission error, contact ratio and sliding ratio of the VCML gears are analyzed by finite element method, and the area of significant performance improvement of the meshing line center of the VCML gears is found. The research results show that compared with involute gears, the maximum average stress of VCML gears is reduced by 64.99%, the meshing stiffness is increased by 193.67%, and the transmission error is reduced by 65.95%. This method improves the efficiency of new tooth profile design and transmission performance. By changing the center coordinates of the meshing line, the tooth profile of the VCML gear can be quickly redesigned, which greatly improves the efficiency of the new tooth profile design and transmission performance. This design method provides a new idea for the tooth profile design of internal meshing gear.

Flank fractures on spiral bevel gears—transfer of analytical methods for the estimation of residual stresses from cylindrical gears to bevel gears

The classic flank and root load capacity calculation on the component surface forms the basis for the design of power gears today. However, flank fractures also occur in practice, particularly with large-module gears and/or low case-hardening depths. It is a fatigue damage with crack initiation in the tooth interior, its prevention requires the calculation of the stresses below the surface. In addition to understanding the load stresses, the inhomogeneous load bearing capacity and the residual stress profile in case-hardened gears are also of great importance. There are various calculation approaches for this in the area of cylindrical gears, but these have not yet been transferred to the complex geometry of spiral bevel gears. The focus of this publication is on estimating the residual stresses in the tooth volume by generating a three-dimensional residual stress tensor field in the bevel gear tooth based on the two-dimensional calculation approaches used to date on cylindrical gears. In combination with the stress tensor-time curves from a tooth contact simulation with the LTCA tool BECAL, this can be fed into different failure hypotheses, which is illustrated using an example.

The Differentiated Creative Search (DCS): Leveraging differentiated knowledge-acquisition and creative realism to address complex optimization problems

This article introduces differentiated creative search (DCS), a groundbreaking optimization algorithm that revolutionizes traditional decision-making systems in complex environments. In contrast to conventional differential evolution methods, DCS integrates a unique knowledge-acquisition process with a creative realism paradigm, thereby transforming optimization strategies. The primary aim of DCS is to enhance decision-making efficacy by employing a newly proposed dual-strategy approach that balances divergent and convergent thinking within a team-based framework. High-performing members apply divergent thinking via the DCS/Xrand/Linnik(α,σ) strategy, which incorporates existing knowledge and Linnik flights. Conversely, the remaining team harnesses convergent thinking through the DCS/Xbest/Current-to-2rand strategy, which combines insights from both the team leader and fellow members. This division of labor, coupled with a strategy tailored to the performance levels of team members, allows for a dynamic and effective decision-making process. The methodology of DCS involves iterative cycles of divergent and convergent thinking, supported by a differentiated knowledge-acquisition process and retrospective assessments. The algorithm's novelty lies in its differentiated knowledge-acquisition, adjusted based on individual team member performance, fostering an environment of continuous learning and adaptation. The paper's contributions are demonstrated through rigorous testing of DCS on various benchmark functions, including CEC2017, classical, and sensor selection problems, as well as real-world applications such as car side impact design, gear train design, and FM sound wave parameter estimation. The results showcase the promising performance of DCS compared to that of existing algorithms, attributable to its innovative approach to problem solving and decision making in complex scenarios. The results and impact section highlights that DCS considerably outperforms traditional optimization algorithms, offering a robust and versatile tool for complex decision-making systems. Its impact is particularly notable in scenarios requiring a balance between innovative solutions and practical decision-making, making DCS a valuable asset in strategic planning and execution across various industries.

Improving the Load Carrying Capacity through Asymmetric Spur Gear using WC-Fe Metal Matrix Composite for Automobile Applications

Gears are the components that have been used for a century to transmit power from one place to another place. Symmetric spur gears are commonly used in the gearbox to transmit power between two parallel shafts. In order to increase the load carrying capacity of the spur gear with reduced noise and vibration, its profile can be modified. This can be achieved by changing the gear tooth design into asymmetric form. Asymmetrically toothed gears are used in power transmission for transmitting the power in one direction. These teeth help to improve the load carrying and power transmitting capacity of the gear. The strength can be further increased by changing the material used in gears. This can be made possible by using Metal Matrix Composite as a gear material. The metal matrix composites have high stiffness and strength to weight ratio compared to the Alloy Steel. The main objective of this project is to increase the load carrying capacity of the spur gear by using WC-Fe metal matrix composite material. The symmetric and asymmetric gear modeling has been done for existing car gear (Maruthi 800) using Ansys parametric design language software. The contact stress, bending stress and von Mises stress of the composite, as well as conventional gear material, is analyzed and the results are compared to find the percentage increase in strength of the gear.

Effect of the coefficient of friction on gear-tooth root fatigue for both dry and lubricated running polymer gears

Polymer gears are increasingly popular for a variety of applications due to their improved performance, light weight, ease of manufacture and low cost. However, the design of polymer gears and predictions of their useful operating lifetimes require refinements based on a better understanding of all the influential parameters. For example, do dry and lubricated running polymer gears operating with the same tooth-root temperature and under the same load/torque experience different fatigue lifetimes? To investigate this question, the fatigue lifetimes of dry and oil-lubricated polymer/steel gear pairs were experimentally evaluated under three different loads (0.8, 1.0 and 1.2 Nm) and two different tooth-root temperatures (25 and 80 °C). For all the experimental conditions, the finite-element method was employed to gain a better insight into the observed differences. Finally, the decomposition of the loads acting on the gears was used to understand the effect of friction, which is different for dry and lubricated conditions, and changes direction before and after the pitch point. The lower friction in the lubricated conditions results in up to 13% less maximum stress in the tooth-root, which can have a non-linear effect on the polymer’s lifetime, resulting in a 2–5.2-times-longer fatigue life compared to dry-running gears under the same load/torque and temperature.

Data-Driven Multi-Objective Optimization Approach to Loaded Meshing Transmission Performances for Aerospace Spiral Bevel Gears.

Loaded meshing transmission performance optimization has been an increasingly significant target for the design and manufacturing of aerospace spiral bevel gears with low noise and high strength. An innovative data-driven multi-objective optimization (MOO) method is proposed for the loaded meshing transmission performances of aerospace spiral bevel gears. Data-driven tooth surface modeling is first used to obtain a curvature analysis of loaded contact points. An innovative numerical loaded tooth contact analysis (NLTCA) is applied to develop the data-driven relationships of machine tool settings with respect to loaded meshing transmission performance evaluations. Moreover, the MOO function is solved by using an achievement function approach to accurate machine tool settings output, satisfying the prescribed requirements. Finally, numerical examples are given to verify the proposed methodology. The presented approach can serve as a powerful tool to optimize the loaded meshing transmission performances with higher computational accuracy and efficiency than the conventional methods.

FORGEABILITY OF 25%GRPOM ( CELCONR ) TOPRODUCE SPUR GEAR UNDER HOT CONDITIONSTHROUGH SLOW SPEED PRESS.

This research studied forgeability of preheated billet of 25%GRPOM plastic through closed die forging technique using spur gear design. The type of deformation was discussed as well. This process had done after heating the billet and die assembly at 100oC to achieve complete gear shape taking into consideration testing the product to insure no inside or outside defects with improvement in the mechanical properties. Cycle time to produce a complete shape was two minutes.

Design and tooth geometric trait analysis of helical noncircular gears based on a novel mathematical model

Design and tooth geometric trait analysis of helical noncircular gears based on a novel mathematical model

Meshing equation, tooth contact analysis, stress analysis and manufacture of a point-contact gear formed by double-arc milling cutter

The processing and design of point-contact gears have attracted the interest of many scholars. The point-contact gears are usually processed by specialized machines (face-milling and face-hobbing) or five-axes machines (forming milling). In this paper, a new type of point-contact gear formed by double-arc milling cutter on four-axes machine is proposed. Firstly, the meshing equation is proposed to obtain a pair of processing traces that satisfy the law of gearing, and the processing traces are also contact traces. Considering the important role of traces in obtaining the proposed gear, this gear is called as TG. Then, six pairs of contact traces for parallel-axes, crossing-axes, and skewing-axes TGs are solved. Furthermore, the tooth surface models are studied and the obtained models are used for tooth contact analysis and stress analysis, and then the instantaneous contact areas, the contact stresses, and transmission errors are obtained, respectively. Lastly, the TG pair with cross-axes is processed, and then, the measurement and rolling experiments are conducted. The obtained results indicate the meshing equation, tooth surface models, and milling method are feasible. The proposed milling method provides a new way for flexible and diversified manufacturing of point-contact gears.

Face gear drives: Nominal contact stress calculation for flank load carrying capacity evaluation

Face gear drives are angular gear units in which an involute pinion meshes with a face gear wheel. Spur and helical face gear drives are possible with or without center offset. Face gear drives can be manufactured on conventional gear cutting machines. Furthermore, the pinion is free to move axially and such displacements have no effect on the contact pattern. This makes them a promising gearing for various applications. Due to the lack of established calculation standards, the design of face gear drives is a challenge and often results in oversizing or early failures. This may also be why face gear drives have not yet established themselves in power transmissions. Instead, the main application can be found in kinematic/auxiliary drives. In this paper, two methods for contact stress calculation for face gear drives with any configuration between helix angle and center offset are developed. Calculation examples compare the two methods and confirm the applicability. Overall, this study provides a new standard-capable easy-to-program calculation method for the contact stress based on existing standards for cylindrical gears.

Experimental Study on High-Speed Aviation Gear Scuffing Based on Tooth Profile and Surface Treatment Improvements

Scuffing failure in high-speed aviation gears is a critical issue that hinders the improvement of operating performance and reliability in modern aviation equipment. The unclear failure mechanism limits the effective design of anti-scuffing measures. In this study, a scuffing test method was designed for high-speed aviation gears to investigate the effects of tooth profiles and surface treatment on the gear scuffing performance. The results indicate that both the pressure angle and surface treatment significantly affect gear scuffing behavior. Under different geometric treatment states, the range of the Ryder load stages at which gear scuffing initiated was between 5 and 13. The 25° pressure angle gear with barrel finishing treatment exhibited the optimal anti-scuffing performance. Compared to the ground state, barrel finishing increases gear scuffing loading capacity by 30% to 33%. Tooth profile optimization based on pressure angle changes improves gear loading capacity by 56.9%. This work provides an exploration of the anti-scuffing design of high-speed gears.

Effect of Rim and Web Thickness on Tooth Root Stress of Spur Gear

This study investigated the impact of spur gear rim and web thickness on root stress. A finite-element analysis model (FEM) was utilized and validated through a gear-bending test. Four gears with different rim and web specifications, including a solid gear, were designed and tested using strain gages to measure their root stress. The 3D FEM was validated by comparing the measured root stresses with that analyzed by the developed FEM. Using this model, a parametric study was conducted by varying the web position, pressure angle, and module to investigate the effect of the backup ratio on the root stress ratio of the gear. A stress-ratio map was generated based on the results. This stress-ratio map was compared with the rim thickness factor (YB\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${Y}_{B}$$\\end{document}) for external spur gears specified in ISO 6336-3. The comparison reveals that the rim thickness factor specified in ISO 6336 is overly conservative compared to values obtained in this study. Our results suggest that the thickness of both the rim and web should be considered to reduce the weight of spur gears. These findings can be applied to the design of lightweight spur gears.

Analysing Bevel Gears for Efficient Power Transmission: A Study on Design, Simulation and Performance Assessment

Bevel gears find application in transmitting motion between unequally aligned shafts, typically forming a 90° angle relative to each other. Some of the several types that are available commercially are the straight bevel, the Zerol bevel, the spiral bevel, and the hypoid. Stainless steel, gray cast iron, titanium alloy and structural steel were used for the behavioural assessment. The design and modelling of the straight bevel gears were carried out using SolidWorks 2015, while ANSYS 18.2 was employed simulating to simulate the gears' stress and deformation. The 3D solid model generated using SolidWorks was imported into ANSYS, where the analysis was conducted using the finite element software, ANSYS Workbench. Stress distribution plot, deformation plot, and equivalent strain plot were generated. The highest stress, measuring 73.536 MPa, became evident as the load concentrated near the base of the gear teeth. The finite element analysis revealed a minimal likelihood of gear failure, and the least deformation was observed in the structural steel configuration, resulting in a deformation of 8.2354 x 10^-3 mm. Consequently, the gear pair can successfully transmit 6 kW of power without experiencing any failures with a good safety factor

Research of the influence of element deformation and manufacturing errors of planetary gears on the load distribution among satellites

A technologically advanced multi-satellite design of a toothed planetary gear is studied, in which the carrier is made in the form of two cheeks, which are connected to each other by the axes of the satellites, which act as jumpers. The problem of the stress-strain state of mating elements is solved using differential equations of the curved axis of the satellite, represented by a beam on an elastic foundation. The distribution of the load across the satellites is determined taking into account the deformation of the gear segments and the non-adherence of the gear teeth caused by errors in its manufacture. Keywords:planetary gear, non-rigid carrier, compliance of segments, load distribution Alexandrsun4009@gmail.com

Geometric parameter design and contact characteristics of beveloid gear and involute cylindrical gear transmission with crossed axes

Geometric parameter design and contact characteristics of beveloid gear and involute cylindrical gear transmission with crossed axes

Multi-Objective Optimization Design of Cycloid-Pin Gears Based on RV Reducer Precision Transmission Performance

This paper aims to realize multi-objective optimization of cycloid-pin gears to improve the positioning accuracy and load-carrying capacity of the rotary vector (RV) reducer, via the consideration of backlash, transmission error, and torsional stiffness. Initially, the analytical models of the RV transmission backlash and transmission error are developed by using both purely geometrical and equivalent model methods individually. Based on the generalized Hooke’s law, a torsion angle model is established to characterize the torsional stiffness of the system, utilizing methods such as Hertzian contact theory and bearing stiffness models. Subsequently, employing the Monte Carlo method, extremum method, and quality loss function, mapping objective functions for dimensional accuracy (tolerance) and transmission performance (backlash, transmission error, and torsional stiffness) are constructed. The geometry dimensions, dimensional accuracy, and modification of the cycloid-pin gear are considered as design variables to create a multi-objective optimization model. The improved Parallel Adaptive Genetic Algorithm using Deferential Evolution (PAGA-DE) is used for multi-objective solutions. Through example calculations, the impact of cycloid-pin gear parameters on transmission performance before and after optimization is determined. The reliability of backlash after optimization within 1.5′ reaches 99.99%, showing an increase of 8.24%. The reliability of transmission error within 1′ reaches 98.52%, demonstrating an increase of 1.35%. The torsional angle is reduced by 8.9% before optimization. The results indicate that the proposed multi-objective optimization design method for cycloid-pin gears can achieve the goal of improving the transmission performance of the RV reducer.

Design and Manufacture Method of Aviation Face Gear With High Load-Bearing Based on Gear Skiving Process

Abstract Face gear drive has been widely investigated in the aviation field as a power split device on the helicopter main reducer. However, high-speed and heavy-load condition makes the face gear prone to tooth surface pitting, leading to deterioration of transmission performance. To improve the load-bearing capacity of face gear, this paper proposes a design and modification method based on gear skiving process for face gear drives. First, gear skiving mathematical models for a face gear pair are established, and a continuously profile-shifted modification method is presented based on these mathematical models. Then, the load-bearing capacity of the modified face gear pair is minutely analyzed and discussed through contact analysis. The contact stress of the modified face gear is reduced by 47.78% on the right side and 41.1% on the left side compared with an unmodified face gear. Finally, gear skiving experiments and meshing performance tests of face gear pairs are conducted. The measurement results show consistency with the calculation results. Thus, the proposed design and continuously profile-shifted modification method based on the gear skiving process is feasible and contributes to load-bearing capacity improvement.

Numerical modeling and experimental investigation on fatigue failure and contact fatigue life forecasting for 8620H gear

Surface integrity parameters exert an enormous function on contact fatigue performance of gears. In this paper, a gear contact fatigue life prediction model that incorporates surface integrity parameters is proposed. The micropitting and pitting damage of failed gears are quantitatively analyzed through micro-characterization techniques. A three-dimensional contact analysis of rough surface is performed to simulate the morphology evolution during gear running-in. And the coupling effect of residual stress and rough morphology on the contact stress field and fatigue life is analyzed. Finally, residual stress optimization design is carried out based on the failed gear. Gears subjected to shot peening are designed and gear contact fatigue tests under various working conditions are performed. The research results indicate that the plastic deformation at the asperities level in the running-in process mainly occurs during the initial loading. The fatigue life significantly increases by improving the residual stress distribution on the tooth surface through shot peening process. The maximum relative error between predicted fatigue life and measured fatigue life is less than 20%, which effectively verifies the accuracy of the proposed model. The technique presented in this study could provide theoretical basis and data support for the anti-fatigue design and manufacturing of gears.

A time‐varying meshing stiffness model for gears with mixed elastohydrodynamic lubrication based on load‐sharing

AbstractIn mixed elastohydrodynamic lubrication (EHL), the load distribution between the gear meshing surfaces is shared by the oil film and the asperities of the gear's rough surface. Based on the load‐sharing concept, this paper proposes a time‐varying meshing stiffness (TVMS) model for gears with mixed EHL. The initial step involves the utilization of the Greenwood‐Williamson model to calculate the contact stiffness of surface asperities, while the lubricating film is assessed using a curve‐fitting formula to investigate the influence of gear surface morphology on TVMS. Subsequently, the incorporation of gear fillet foundation deformation and friction enables accurate TVMS determination. The proposed method is employed to examine the meshing stiffness of the gear pair under both dry lubrication and EHL conditions. Comparative analysis reveals favorable agreement between the proposed model and experimental results obtained under dry lubrication, thereby highlighting the superior performance of the proposed approach. Moreover, the time‐varying friction coefficient under EHL is computed, and the impacts of gear surface morphology parameters, temperature, speed, and load on lubrication conditions and TVMS are investigated. The findings presented in this paper contribute significantly to advancements in gear design and performance.