Gear Mechanism Research Articles

Mechanical structures of sidewalk plants: Anatomical evaluation

The mechanical structure of plant tissues has recently attracted a lot of attention. The present study aims to evaluate the importance of collenchymatous and sclerenchymatous tissues in supporting plant species in their harsh environments like road and street plant habitats. Dicots and monocots are classified into different models according to the types of supporting mechanisms. Mass cell percentage and soil analysis are used in this investigation. The tissues are distributed with different percentage masses and arrangements to overcome various severe conditions. Statistical analyses enhance the role of these tissues and clarify their significant values. The gear support mechanism is claimed to be the perfect mechanical method used.

Structural design and mechanics research of a bionic pelican floating object fishing device

In order to meet the needs of surface floating objects fishing operations in small areas such as lakes and rivers, a fishing device is developed that can be used for high-intensity operations and is highly adaptable to the environment. In this paper, a water and land type bionic pelican surface floating object fishing device is developed based on the MeArm robotic arm combined with a three-degree-of-freedom linkage robotic arm using bionic principles. In order to meet the needs of the fishing function, the overall structure of the surface floating object fishing device was bionically designed by combining the large beak and flexible neck of the pelican, The innovative design of the mouth lower beak opening and closing mechanism, the lower beak gear rack lever slide mechanism, the mouth throat pouch bottom release mechanism and the neck structure are mainly carried out.The structural strength of the device under the most dangerous operating conditions was simulated using finite element analysis software for statics and dynamics simulation. The research results show that the structure of this design is reliable, and the experimental test of the prototype model verifies the validity and reliability of this design scheme, which provides the theoretical and experimental basis for the further development of the subsequent products.

Design and Development of an Engine-Operated Weeding Machine for Wheat Farm

Weeds constitute a serious problem to wheat crops and cause a great loss to the yield. Manual weeding is labor-intensive and time-consuming. Chemical weed control has a negative impact on both the environment and humans. To overcome these problems, an engine-operated weeder was designed and developed at Asella Agricultural Engineering Research Center (AAERC). The developed weeder was designed on the basis of agronomic and machine parameters. The developed prototype weeder consists of the mainframe, weeder blade, ground wheel, and power transmission system. The rated engine speed of 2800 rpm was reduced to 46 rpm of the ground wheels by using bevel gear, chain, and sprocket mechanism in three stages. The overall dimension of prototype weeder was 1650 mm in length, 800 mm in width and 1050 mm in height. The total production cost of the engine-operated weeder was 11,409.92 ETB. This paper is focused on machine design analysis and fabrication of prototype. Performance evaluation of propototype would be addressed in the next coming paper.

A Novel Device for Studying in Vivo Magnesium Degradation under Controllable Cyclic Load in the Rabbit Model

Magnesium is an important material for medical implants due to its special properties including biocompatibility, low density, high mechanical property, and biodegradability. The in vivo implantation experiment of magnesium is an important experimental method to obtain its degradation characteristics. In recent years, although in vitro studies have found that the degradation of magnesium under cyclic loading is different from static loading, there is the lack of in vivo experiment to verify the above in vitro results, while the degradation characteristic of magnesium under load is an important factor to be considered when magnesium is used as orthopedic implant. We designed a novel device to apply controllable cyclic load onto the magnesium material implanted in the rabbit tibia, containing loading chamber, motor and gear reduction mechanism, and Singlechip Computer, etc. The conducted experiments have shown that the devices were able to apply load onto the implanted magnesium in rabbits in vivo during unrestricted cage activity for at least 16 days. Likewise, no distortion or infections were observed. Results demonstrated that the novel device was able to produce alteration of the mechanical environment in vivo rabbit tibia, which showed that the load device is suitable for in vivo loading degradation characteristics testing of magnesium or magnesium alloys.

A novel tuned inerter eddy current damper: modeling, optimization, and evaluation

This study proposes a novel tuned inerter eddy current damper using a rack and gear mechanism (TIECD), in which the configuration and mechanical model are introduced in detail. The TIECD design procedure for the seismic control of primary structures is established based on the effective damping ratio enhancement (EDRE) effect. A closed-form solution for TIECD optimal design under white noise excitation is presented using stochastic linearization techniques (SLT) with force-based and energy-based equivalence criteria. The control performance of the TIECD obtained by the closed-form solution, including the EDRE effect and effective damping ratio, is in good agreement with the numerical results obtained from the Monte Carlo simulation when a suitable TIECD critical velocity is selected; a large critical velocity is conducive to improving the accuracy of the closed-form solution. Note that the effect of a low structural damping level on the optimal design of TIECD can be ignored, which is beneficial in practical engineering applications because structural damping cannot be precisely known in most cases. Furthermore, several numerical studies have been conducted to investigate the availability of TIECD under real seismic excitations. The results indicate that the effectiveness of TIECD in mitigating the seismic response of primary structures is approximately the same as that of a tuned viscous mass damper (TVMD) and much greater than that of the viscous and eddy current dampers with the same damping parameters. It can be considered that the maximum damping force and maximum deformation of TIECD and TVMD are the key design factors for short-period and long-period structures, respectively, and the advantages of TIECD over TVMD are owing to the damping force limiting characteristics and small deformation.

"STRENGTHENING THE DESIGN OF SCREW DEVICES IN HORIZONTAL MACHINES"

"Methods of reducing the metal consumption and increasing the structural strength of screw devices through the use of tubular shafts with amplifiers in dangerous sections are proposed. The review of the study shows that the modernization of the design of horizontal machines with screw devices was previously carried out and there is a positive experience in the development of such structures. The configuration of the shafts of mechanical gears usually provides the necessary rigidity of the structure. The load part of such shafts is thickened, less loaded on the shank has a thinned configuration with a smaller volume of material assigned to it. Due to the use of a special annular bandage pressed onto the screw shaft, the composite shaft is reinforced, representing a solid structure of hollow cylinders interconnected by guaranteed tension. The reduction of metal consumption is ensured by reducing the mass of the shaft, only dangerous sections are reinforced with bandages, which makes it possible to significantly facilitate the design of screw devices and increase the energy efficiency of the machine as a whole. Keywords: horizontal machine, screw device, shaft, annular insert, fit, strength, rigidity."

Research on surface defect detection and fault diagnosis of mechanical gear based on R‐CNN

AbstractGears are the basic units in modern power systems. The detection and diagnosis of surface defects and faults in gears are conducive to improving product quality, ensuring the safety of mechanical equipment, and reducing maintenance costs. However, the accuracy of manual and traditional automated target detection algorithms is not satisfactory. Therefore, this research uses the R‐CNN algorithm for gear detection, improves its non‐maximum suppression algorithm and multi‐task loss function, and obtains the improved Faster R‐CNN algorithm. The test was carried out on the built data set. The actual measurement shows that the recall rate of the improved Faster R‐CNN is up to 0.951 and the lowest is 0.816. Its AP value is as low as 0.677 and as high as 0.858, and the mAP value is 0.843. Horizontal comparison, the comparison results show that the mAP of Faster R‐CNN is 0.80 1, second only to R‐CNN among the tested algorithms, and 8.83% higher than the original Faster R‐CNN. Under the condition of AP@0.5:0.95, among all the tested algorithms, its AR index is the highest at 54.3, and the detection speed is 18 FPS/s. Although the detection speed has decreased, the detection and recognition accuracy has been significantly improved, which provides feasibility for the R‐CNN series of algorithms new optimization directions. The research provides a better automatic detection method for product quality inspection in gear manufacturing industry.

Aerodynamic Evaluation of Flapping Wings with Leading-Edge Twisting

The purpose of the current study is to emphasize the characteristics and phenomena of leading-edge twisting in flapping wing vehicles. A fused deposition modeling (FDM) 3D printing method is applied to develop the flapping mechanisms with bevel gears to achieve the leading-edge twisting. Three flapping mechanisms were developed, including simple flapping only (type-A1: normal servo mechanism), flapping with continuous leading-edge twisting (type-B: servo-bevel gear mechanism), and flapping with restricted leading-edge twisting via mechanical stoppers (type-B1: servo-bevel gear mechanism with adjustable mechanical stoppers). Utilizing a low-speed wind tunnel, the aerodynamic performances of these mechanisms are examined by extracting their lift and net thrust forces. The wind tunnel testing data showed that the flapping with restricted leading-edge twisting via mechanical stoppers (type-B1) showed better performance than the simple flapping (type-A1) by 32.9%, and also better performance than the flapping with continuous leading-edge twisting (type-B) by 64%. Next, MATLAB software was used to create the 3D wing surfaces from the instantaneous stereophotography Kwon3D trajectories to fully sketch the leading-edge twisting features. The 2D airfoil cut sections at the mean aerodynamic chord at different stroke moments depict the instantaneous angles of attack to justify the aforementioned wind tunnel testing data and it was verified using a theoretical trajectory model. This comprehensive study using the 3D-printed mechanisms is well suited for the quantitative evaluation of the lift contribution from leading-edge twisting.

Electro‐Reconfigurable Adaptive Microlens with Simultaneous Multidirectional Focal Adjustment and Zooming

AbstractElectrically reconfigurable lenses capable of focal adjustment and zooming require deformable adaptive optical components. However, existing electroactive optical devices that perform these functions are limited by fluid leakage or require complex mechanical parts. Although polyvinyl chloride (PVC) gel‐based lenses with variable focal lengths and zooming have recently been developed, focal adjustment can only be made in the horizontal axis. Herein, a PVC gel‐based adaptive microlens capable of controlling the focal length and focal point simultaneously in the vertical, horizontal, and diagonal directions without mechanical gears or liquid leakage is presented. By optimizing the characteristics of PVC gels plasticized with three different structured plasticizers, a PVC gel‐based adaptive microlens is fabricated. The produced microlens demonstrates the properties of multidirectional focal adjustment, variable focal length (+33.7 to −15.1 mm) at low input voltages (<300 V), excellent transparency (>90%), fast response (0.10 s at 100 V), silent operation, low power consumption (0.39 mW), and excellent potential for further miniaturization.

Vibration and cavitation in high-speed gears caused by faults

In high-speed gear transmission, cavitation occurs easily due to vibration. When gear has pitting or crack fault, the cavitation will be more violent due to stronger vibration, causing potential safety hazards. However, researches on gear cavitation mechanism considering pitting and crack are limited. For studying the cavitation mechanism of faulty gear, a model combined computational fluid dynamics and faulty gear dynamics has been proposed, being regarded as the innovation of this paper. The dynamic characteristics of the faulty gear is obtained by solving the gear finite element model, and the results will be applied to the analysis of lubricating oil flow characteristics as boundary conditions. For proving the validity of the proposed model, the simulation results are compared with the available experimental results. Moreover, the novelty of this paper is to consider the influence of gear failures on cavitation, factors such as rotational speed, pitting depth and crack depth are discussed, tooth profile changes are also considered. The results indicate that gear faults have greater impact on cavitation at high speeds. At 10,000 rpm, with the deepening of pitting, the cavitation intensity will increase firstly and then decrease. When the pitting depth increases from 0.2 mm to 0.3 mm, the root mean square value of average vapour volume fraction decreases from 0.0752 to 0.0724. For cracked gears, the crack depth will affect the cavitation enhancement rate. The increase rate of cavitation decreases from 17.4 to 1.1% when crack depth increases from 1 to 4.5 mm. This study provides an effective tool for gear cavitation suppression and high reliability.

Effect of parameters of the stereolithography process on the part quality

This paper investigates the effect of additive manufacturing parameters on the manufacturing quality of selected gear mechanism components. Three input variables, and two output variables were determined. The result was the determination of the most optimal combination of key parameters and the determination of regression equations. The concept of manufacturing objects of a very complex shape, by any person, under various conditions through the use of a low-cost device became the basis for this thesis topic. Curing time, layer thickness, and lift speed are among the basic parameters, with a large range of manipulation. A hypothesis was formulated that these three parameters are crucial to produce a part with the smallest possible deviations from the computer model. A handheld scanner was used to scan the samples and compare them with the CAD model. Based on the study, optimal parameters for layer thickness, curing time and lift speed were proposed.

Effects of tooth root cracks on vibration and dynamic transmission error responses of asymmetric gears: A comparative study

Gears are significant machine elements used in various industrial applications. An undetected fault in a gear transmission system may lead to a fatal breakdown and, thus, severe economic losses or even human casualties. From this standpoint, the present study developed a numerical method to detect root crack damages in symmetric and asymmetric involute spur gears. To achieve this end, the single tooth stiffness values were calculated for healthy and cracked (25%-50%-75%-100%) gears, and then the time-varying mesh stiffness was obtained. A six-degree-of-freedom dynamic model of a single-stage gear mechanism was developed to collect vibration and Dynamic Transmission Error (DTE) signals. The efficacy of vibration and DTE responses in fault detection was compared through six statistical indicators. The results indicate that the vibration signals were more effective than DTE in detecting tooth root cracks. It was observed that the statistical indicator changes significantly increase with the increment of the drive side pressure angle from 20° to 30° for the backup ratios where the root crack propagates along the tooth, thus making fault detection easier. The findings could provide significant outputs for a better understanding of the influence of tooth asymmetry on gear dynamics characteristics and early fault diagnosis.

Design and Development of an Engine-Operated Weeding Machine for Wheat Farm

Weeds constitute a serious problem to wheat crops and cause a great loss to the yield. Manual weeding is labor-intensive and time-consuming. Chemical weed control has a negative impact on both the environment and humans. To overcome these problems, an engine-operated weeder was designed and developed at Asella Agricultural Engineering Research Center (AAERC). The developed weeder was designed on the basis of agronomic and machine parameters. The developed prototype weeder consists of the mainframe, weeder blade, ground wheel, and power transmission system. The rated engine speed of 2800 rpm was reduced to 46 rpm of the ground wheels by using bevel gear, chain, and sprocket mechanism in three stages. The overall dimension of prototype weeder was 1650 mm in length, 800 mm in width and 1050 mm in height. The total production cost of the engine-operated weeder was 11,409.92 ETB. This paper is focused on machine design analysis and fabrication of prototype. Performance evaluation of prototype would be addressed in the next coming paper. Keywords: Design analysis, develop, wheat, weeds, weed control, weeding machine DOI: 10.7176/ISDE/13-1-01 Publication date: March 31 st 2023

Review on Failures, Design and Material Optimization Techniques in Aircraft Landing Gear Mechanism

Abstract: Landing Gear is proved to be the most critical subsystems in aircraft. It is a crucial part in all ground operations, takeoff and landing of aeroplane. Landing gear operates as dead weight after an aircraft is in the air, burning more fuel and taking up room which can be used for other safety measures. When taking into account all the legal and safety standards, it is vital to shorten the time needed for the landing gear design and its development cycle. All aerospace sectors strive for attributes such as minimal weight and volume, great performance, and reduced life cycle costs. Our objective was to create a landing gear with the least amount of weight and volume while maintaining maximum structural integrity. To achieve this goal, we designed landing gear links using generative design. In addition to this, we also studied different parameters considered for landing gear design.

Comprehensive Performance Evaluation of Landing Gear Retraction Mechanism in a Certain Model of Aircraft Based on RPCA Method

The performance of landing gear retraction mechanism in aircraft directly affects its safe operation. Therefore, it is important to analyze and evaluate its comprehensive performance during the design process. Multiple single kinematic and dynamic performance indexes of landing gear retraction mechanism could be solved by CAD/CAE software. The weighting factors of every single performance index are used to distinguish the different effects of comprehensive evaluation, and also achieved by the expert investigation method. Combining the a priori information of the mechanism, the comprehensive performance of landing gear retraction mechanism could be analyzed by Relative Principal Component Analysis (RPCA) method, and the scale of the landing gear retraction mechanism with the best comprehensive performance could be effectively selected. Further, RPCA could also provide a scientific reference basis for the optimization design of landing gear retraction mechanism.

Dynamic Response Characteristics of the Hydraulic Rotary System of an Azimuth Thruster for a Dynamic Positioning Vessel

The composition characteristics and working principle of the hydraulic rotary system of the azimuth thruster were analyzed. The mathematical model of the rotary dynamic system of the pump-controlled hydraulic motor driving the gear reduction mechanism was established. Additionally, a fast tracking method for the azimuth angle of the azimuth thruster was proposed to analyze the rotary azimuth angle, angular velocity and dynamic response characteristics of the hydraulic system for different desired azimuth angles. The simulation results show that the established dynamic model can simulate the rotary motion response process of the real thruster, and can realize the rapid and accurate tracking of the azimuth angle. At the same time, the physical constraints of the rotary dynamic response were established. It provides an important reference for research on the motion control methods of dynamic positioning vessels.

A Review of Magnetic Gear Technologies Used in Mechanical Power Transmission

This paper presents a literature review on magnetic gears, highlighting the advantages of using these technologies for mechanical power transmission applications in wind energy conversion systems and transportation, such as in electric vehicles. Magnetic gear technologies have important advantages over their mechanical counterparts. They can perform the speed change and torque transmission between input and output shafts by a contactless mechanism with a quiet operation and overload protection without the issues associated with conventional mechanical gears. The paper describes the fundamentals and operating principle of the field-modulated magnetic gear topologies and investigates the magnetic torque transmission mechanism. However, despite all the advantages highlighted in different research and development reports, there is still no convincing evidence to show that magnetic gear technologies are an acceptable alternative for industrial applications. The aim of this paper is to summarize previous work on magnetic gears to identify the topologies most suited for mechanical power transmission systems in wind energy conversion systems and electric vehicle applications. These applications will show that research and development of magnetic gear technologies contribute significantly to solutions for sustainable systems, a subject to which our current civilization must pay a lot of attention.

Gear Shift Quality Enhancement Parameters in Light Commercial Vehicles

In the present scenario enhancements of human ergonomics in Light commercial vehicles are imperative to implement customer comfort in vehicle level. Thus the gear shift mechanism plays an important role in the interface between the driver and vehicle. An exact and smooth running gear shift feel typically depends on the combination of both internal and external shifting elements of the gearbox and Change shift operation(CSO) system. The objective of this paper is to explain the parameters that impacts the gear shift quality and how it is improved by taking multiple design iterations in Light commercial vehicle platform through both objective and subjective evaluations. These iterations are given better results on gear shift feel in dynamic as well as static condition. This lead us to facilitate better shift comfort to end users. The content of the paper is limited to the scope of gear shift quality improvements at manual transmission and change shift operation components.

Constructing a Single-Motor Hybrid Driving Mechanism for Completely Hybrid Electric Cars

This research focuses on the design and development of a single-motor hybrid driving device for full hybrid electric vehicles. The device integrates an internal combustion engine, an electric motor/generator, and a power conversion device. The power conversion device incorporates a planetary gear mechanism and a stepless speed change mechanism, providing efficient power transfer between the engine, motor/generator, and the vehicle's drivetrain. The objective is to create a versatile hybrid system that meets the requirements of fuel economy and dynamic performance, particularly suitable for plug-in hybrid electric vehicles.

Perfect static balancing using Cardan-gear spring mechanisms

This paper presents the static balancing designs (i.e., gravity compensation) for a rotating link by using a special straight-line geared mechanism with springs. The design scenario is to attach the rotating link yet to balance onto an inverted Cardan gear mechanism which has linear springs installed for balancing the weight of the links. It is found that the whole mechanism can be perfectly balanced in theory through either one or two linear springs. The significance of the proposed designs is that the derived solutions for perfect balancing are general. That is, (1) all the masses of the mechanism links are taken into account in the calculation for balancing, (2) the geometry of the design is formulated through the real-spring model (i.e., not zero-free-length springs), (3) the use of compression or extension springs is thoughtfully discussed, and (4) the installation points, preloaded lengths, initial tensions, and stiffness of the springs are considered altogether in the design process. Based on the original design, several design variations are suggested as well. Applications of the design for balancing two special robotic manipulators are illustrated. Last, an experimental test on a prototyped one-DoF balancer was performed.