Research on lubrication characteristics of asymmetric helical gear based on CFD method

As the most important working area of gear, teeth play the role of transmitting load and power. Tooth line and tooth profile are the two main characteristics of the tooth surface, which affect the shape of the tooth surface, tooth meshing characteristics and contact characteristics. Taking the elliptical cylinder gear pair in the reversing device of a new type of drum pumping unit as the research object, the dynamic meshing process of the gear is simulated by LS-PREPOST software based on loaded tooth contact analysis (LTCA) technology. The distribution law of the effective plastic strain, effective stress and tooth surface pressure in the direction of the tooth line and tooth profile as well as the tooth meshing force under different speed conditions are obtained. The results show that the effective plastic strain, effective stress and tooth surface pressure will decrease with the transition of the center position of the elliptical contact area on the tooth surface to both sides. The distribution of stress and strain in the direction of tooth line will change with the location of the teeth, and the rotational speed has a certain influence on the meshing force of the teeth. The results of this research can provide a theoretical basis for the subsequent analysis of the dynamic meshing characteristics and modification of non-circular gear.

https://www.ije.ir/article_106042_d63952e1727dcc532306eb4940911e69.pdf

Dynamic Meshing Characteristics of Elliptic Cylinder Gear Based on Tooth Contact Analysis

In practical use, most gears have an involute shape of tooth flanks. However, external involute gears have some drawbacks, such as unfavourable kinematic conditions at the beginning and end of meshing, a limited minimum number of teeth, and the highly loaded convex-convex (i.e., non-conformal) contact. Researchers have developed and analysed various non-involute forms of tooth flanks, but they have not been widely accepted. The main reasons are higher manufacturing costs and sensitivity to manufacturing and assembly errors. Analyses of non-involute forms of teeth are mostly theoretical (analytical and numerical), while there is a lack of experimental confirmations of theoretical assumptions. This paper reviews external non-involute shapes, their operating characteristics and possibilities of use compared to involute gears. Established criteria, such as Hertzian pressure, oil film thickness, bending stress at the root of the tooth, contact temperature, and gear noise, were used for assessment. The results of analytical studies and experimental research on S-gears are presented in more detail. S-gears have a higher surface durability and a lower heat load when compared to involute gears. The usability of non-involute gears is increasing with the development of new technologies and materials. However, the advantages of non-involute shapes are not so significant that they could easily displace involute gears, which are cheaper to manufacture.

/pdf/operating-performance-of-external-non-involute-spur-and-4fjmebpy98.pdf

Operating Performance of External Non-Involute Spur˝and Helical Gears: A Review

Axial field flux-modulation permanent magnet (AF-FMPM) machines have been developed for direct drive applications such as wind power generation, HEVs, and railway traction. However, the existing studies on AF-FMPM machines are limited to the PM rotor structure, and less research has been carried out on AF-FMPM machines with PM stator structure. This paper studies two axial field flux-modulation permanent magnet (AF-FMPM) machines, i.e., NS or NN type, which all consist of the same stator and rotor structures but the dual identical outer surface-mounted PM stators face each other in different position. A comprehensive theoretical analysis and global optimization of the AF-FMPM machine based on ANSYS Maxwell 3-D FEA is presented. The performance comparisons between the AF-FMPM machine (NS) and AF-FMPM machine (NN) are presented, including the influence of the critical structural dimensions on the machine performance, phase flux linkage, phase back EMF, cogging torque, and average torque performance. The results show that the phase back EMF and average torque of the AF-FMPM machine (NS) are more sinusoidal and higher than that of the AF-FMPM machine (NN). Furthermore, the NS type machine shows the non-saliency characteristics, while the NN type machine is the salient machine.

/pdf/analysis-and-design-of-novel-axial-field-flux-modulation-iayk9a3l.pdf

Analysis and Design of Novel Axial Field Flux-Modulation Permanent Magnet Machines for Direct Drive Application

The paper proposed a new asymmetrical offset face-gear transmission, applied meshing theory to derive the tooth surface mathematical model, and used discrete numerical methods to obtain the tooth model. Subsequently, the limitation of pointing and undercutting on effective tooth width of asymmetric offset face-gear were studied, and the influence of the eccentricity on the effective tooth width was analyzed. Finally, the finite element method was used to analyze the tooth surface contact stress of four groups of asymmetric offset gear pairs with different working pressure angles. The conclusion shows that the tooth surface contact stress takes the minimum value when the working side pressure angle is 30°, and the contact stress significantly reduced compared to the face-gear pair that does not adopt an asymmetric structure. The research provides a reference to the design of asymmetric offset face-gear.

Design methods and stress analysis of asymmetric offset face-gear transmission

It is well known that the asymmetric gears of the transmission system enhances the load carrying capacity of system, but there is no relevant conclusion about the dynamic load-sharing characteristics of the asymmetric gear transmission system. In order to analyze the dynamic performance of an asymmetric gear system, taking two-stage asymmetric helical gear star drive system as the research object, the load-sharing model of the two-stage asymmetrical helical star gear system is established by the centralized mass method and Newton's second law. The load sharing characteristic of the star gear is studied about the floating member and the tooth profile pressure angle. The influence of eccentricity error, load and input speed on the load sharing performance of the system is analyzed. Based on ADAMS virtual prototype model, through the simulation analysis of the dynamic meshing force of gears, the load sharing coefficient of each star gear is calculated, compare the results with the MATLAB solution to verify the correctness of the theory.

/pdf/research-on-dynamic-load-sharing-characteristics-of-two-1z1aifd8u1.pdf

Research on Dynamic Load-Sharing Characteristics of Two-Stage Asymmetric Star Gear System

The rapid development of the aviation industry has put forward higher and higher requirements for material properties, and the research on smart material structure has also received widespread attention. Smart materials (e.g., piezoelectric materials, shape memory materials, and giant magnetostrictive materials) have unique physical properties and excellent integration properties, and they perform well as sensors or actuators in the aviation industry, providing a solid material foundation for various intelligent applications in the aviation industry. As a popular smart material, piezoelectric materials have a large number of application research in structural health monitoring, energy harvest, vibration and noise control, damage control, and other fields. As a unique material with deformation ability, shape memory materials have their own outstanding performance in the field of shape control, low-shock release, vibration control, and impact absorption. At the same time, as a material to assist other structures, it also has important applications in the fields of sealing connection and structural self-healing. Giant magnetostrictive material is a representative advanced material, which has unique application advantages in guided wave monitoring, vibration control, energy harvest, and other directions. In addition, giant magnetostrictive materials themselves have high-resolution output, and there are many studies in the direction of high-precision actuators. Some smart materials are summarized and discussed in the above application directions, aiming at providing a reference for the initial development of follow-up related research.

/pdf/development-and-prospect-of-smart-materials-and-structures-1gaszuid.pdf

Development and Prospect of Smart Materials and Structures for Aerospace Sensing Systems and Applications

Analytical prediction of quasi-static responses of transmission lines under moving downbursts: A nonlinear model with linear approximation

The applications of sensors in the aerospace industry are mostly concentrated in the middle and high frequencies, and low-frequency sensors often face the problems of low power and short working bandwidth. A lightweight, thin, high-power, low-frequency broadband transducer based on giant magnetostrictive material is designed. The design and optimization processes of the core components are introduced and analyzed emphatically. The finite element simulation results are validated by the PSV-100 laser vibration meter. Three basic configurations of the work panel are proposed, and the optimal configuration is determined by modal, acoustic, and vibration coupling analyses. Compared with the original configuration, it is found that the lowest resonant frequency of the optimal configuration is reduced by 24.6% and the highest resonant frequency within 2000 Hz is 1744.9 Hz, which is 54.2% higher than that of the original configuration. This greatly improves the vibration power and operating frequency range of the transducer. Then, the honeycomb structure is innovatively applied to the work panel, and it is verified that the honeycomb structure has a great effect on the vibration performance of the work panel. By optimizing the size of the honeycomb structure, it is determined that the honeycomb structure can improve the vibration power of the work panel to its maximum value when the distance between the half-opposite sides of the hexagon is H = 3.5 mm. It can reduce the resonant frequency of the work panel; the lowest resonant frequency is reduced by 12.8%. At the same time, the application of a honeycomb panel structure can reduce the weight of the transducer.

/pdf/design-and-optimization-of-high-power-and-low-frequency-2xg9wrpg.pdf

Yue Zong Xiang

Papers

Research on Dynamic Load-Sharing Characteristics of Two-Stage Asymmetric Star Gear System

Development and Prospect of Smart Materials and Structures for Aerospace Sensing Systems and Applications

Analytical prediction of quasi-static responses of transmission lines under moving downbursts: A nonlinear model with linear approximation

Design and Optimization of High-Power and Low-Frequency Broadband Transducer with Giant Magnetostrictive Material