Gear Design Parameters Research Articles

The FEM Analysis and Torque Calculation of REPM Gear

Permanent magnetic (PM) gears are magneto-mechanical devices that are widely used to replace the ordinary mechanical gears and to transmit torque without any mechanical contact. In this paper, according to the demagnetization curve of REPM material and the relationship between magnetic density and intensity of magnetization with magnetic medium in the magnetic field, the magnetic analysis model of PM external gear is built, and its magnetic field distribution is calculated by the finite element method (FEM). The transmission torque is calculated by the Maxwell stress tensor method and its characteristics are studied theoretically. In the end, the torque curves of PM gear are given. From the curves, the influences of geometry size, magnet number, transmission ratio, height of yoke of the magnet on transmission torque are obtained. It cannot only forecast the field distribution to a certain extent, estimate the transmission performance, calculate the transmission torque, but also can give a quantitative direction to the optical design and related parameters of PM gear.

Stress analysis of a helical gear set with localized bearing contact

This study investigates the contact stress and bending stress of a helical gear set with localized bearing contact, by means of finite element analysis (FEA). The proposed helical gear set comprises an involute pinion and a double crowned gear. Mathematical models of the complete tooth geometry of the pinion and the gear have been derived based on the theory of gearing. Accordingly, a mesh-generation program was also developed for finite element stress analysis. The gear stress distribution is investigated using the commercial FEA package, ABAQUS/Standard. Furthermore, several examples are presented to demonstrate the influences of the gear's design parameters and the contact positions on the stress distribution.

Contact Ratios and Transmission Errors of a Helical Gear Set with Involute-Teeth Pinion and Modified-Circular-Arc-Teeth Gear.

Contact ratio (CR) and transmission error (TE) are two significant indices for gear tooth strength and dynamics. This work investigated the CR, contact teeth (CT) and TE of a helical gear pair, composed of an involute pinion and a modified circular-arc gear. Point contact and built-in parabolic TE are obtained due to the modification of the gear’s tooth profile. Tooth contact analysis(TCA) is applied to determine the TE as well as the CR of the proposed helical gear set under various assembly condition. The effect of gear design parameters on the CRs and TEs are also investigated in numerical examples.

Cavity design method for injection-molded spur gears

Mold cavities of gears should be made larger than the product specification since plastics shrink when changing from a molten to a solid state. For injection molded spur gears, two design methods for the compensation of shrinkage are widely used. One is the module correction method and the other is the pressure angle correction method. Both methods are based on the assumption that shrinkage occurs toward the center of a molded gear. This paper deals with the shrinkage rate and proposes a method of designing gear cavity derived from the measured shrinkage rates which govern the outside diameter, the tooth depth and the tooth thickness of a molded gear. The proposed method imposes no restriction on the shrinkage direction and provides a cavity with all of the fundamental gear design parameters.

Stress analysis in worm gears with ground concave worm profile

Stress analysis by a finite element method is carried out in the worm and the gear of a cylindrical worm gear drive with a concave worm profile, ground by a grinding wheel of double arc profile. A computer program, based on finite elements, is developed for the calculation of stress distributions in the worm thread and the gear tooth. By using this program, the influence of the design parameters of the worm gear drive and of the load position on stresses have been investigated. On the basis of the obtained results, by using regression analysis and interpolation functions, equations for the calculation of stresses in the worm thread and in the gear tooth have been derived.

Displacements in worm gears with ground concave worm profile

A computer program based on finite elements has been used for the calculation of displacements in the worm and the gear of a cylindrical worm gear drive with concave worm profile, ground by a grinding wheel of double arc profile. The influence of the design parameters of the worm gear drive and of the load position on displacements has been investigated. On the basis of the obtained results, by using regression analysis and interpolation functions, equations for an easy calculation of displacements in the worm thread and in the gear tooth have been derived.

Landing Gear—the Aircraft Requirement

The trends of major landing gear design parameters are presented reflecting the developments in aircraft performance over the last two decades. These trends illustrate the likely requirements for the future and identify the differences between civil and military landing gears. The aircraft manufacturer will inevitably demand a lower mass landing gear, increased service life and lower support costs of the product, the latter now becoming increasingly important. The method of achieving lower support costs, known as integrated logistic support, is summarized, highlighting the relevance to landing gear design. A number of likely changes required to meet future aircraft demands are discussed and how they will test the innovation and ingenuity of the landing gear designer. Key areas include, (a) stringent turn-round requirements demanded by aircraft operators, (b) computer control of actuation, nose wheel steering and wheel brake control systems and (c) the advent of advanced suspension systems, particularly for military STOVL and repaired runway operations.

Computer-Aided Design of Compact Helical Gear Sets

This paper presents the design strategy for the Computer-Aided Design (CAD) of compact helical gear sets. Using optimization techniques, fundamental gear design parameters such as the number of teeth on the pinion, helix angle, and diametral pitch (or module) are selected subject to constraints on bending stresses, contact stresses, and involute interference limits for both standard and nonstandard gearing. The CAD procedure is illustrated with the help of a design example.

Analysis of the vibratory excitation of gear systems. II. Tooth error representations, approximations, and application

The second part of a theory is presented for predicting the vibratory excitation of gear systems from fundamental descriptions of gear tooth elastic properties and deviations of tooth faces from perfect involute surfaces. The first part of the theory [J. Acoust. Soc. Am. 63, 1409–1430 (1978)] provides expressions for the Fourier-series coefficients of the vibratory excitation, which was shown to be described by the static transmission errors of all pairs of meshing gears in a system. The present paper provides expressions for these Fourier-series coefficients in terms of easily interpreted gear tooth metrics that are readily evaluated from tooth-face measurements. Detailed results are given for rectangular tooth-face contact regions using two-dimensional Legendre polynomial expansions of local tooth-pair stiffnesses and stiffness–weighted deviations of tooth faces from perfect involute surfaces. A rigorous transfer function approach is developed that permits separation of the effects of gear tooth errors and gear design parameters, thereby permitting independent assessment of the effects of gear design parameters on the vibratory excitation. The theory is applicable to both helical and spur gears and is illustrated using measurements of tooth-spacing errors and tooth profiles obtained from a pair of spur gears.

Temperature dependence of resistivity in Ge under pressures of up to 90 kbar : N.N. Kuzin and A.A. Semartchan (Vol. 7, No. 1, pp. 244–250

Due to the presence of non-uniform load distribution, local non-homogeneity of material quality and potential misalignment of gear shafts and bearings, etc., spatial cracks may occur in the fillet region of spur gear teeth. These cracks will eventually propagate in three distinct directions either individually or simultaneously. These directions are the crack depth direction, the tooth width direction and the tooth profile direction. In this paper, an analytical investigation of the influence of spatial crack propagation on the time-varying Gear Mesh Stiffness (GMS) and also the Load Sharing Ratio (LSR) is presented. In order to quantitatively define the spatial crack propagation scenario, the involute spur gear tooth geometry cut with a typical double rounded rack is first determined using two parametric equations. The effects of some gear design parameters and initial crack locations on GMS and LSR are determined and compared with the results from previous papers that used Finite Element Analysis (FEA) in order to verify the proposed analytical model. Finally, a quasi-parabolic crack propagation scenario is assumed, in which 7 propagation cases and 3 typical crack growth paths on the tooth surface are investigated to determine their effect on the maximum reduction of GMS when compared to normal conditions. The results are important for the dynamic simulation of gear transmission behavior, and consequently helpful for the monitoring of gearbox working condition and detection of early crack damage that may exist in gear sets.

On current pulse generation by CdS crystals. : S.I. Shakhovtsova, I.D. Konosenko and E.A. Muzalevsky (Vol. 7, No. 1, pp. 278–279).

Due to the presence of non-uniform load distribution, local non-homogeneity of material quality and potential misalignment of gear shafts and bearings, etc., spatial cracks may occur in the fillet region of spur gear teeth. These cracks will eventually propagate in three distinct directions either individually or simultaneously. These directions are the crack depth direction, the tooth width direction and the tooth profile direction. In this paper, an analytical investigation of the influence of spatial crack propagation on the time-varying Gear Mesh Stiffness (GMS) and also the Load Sharing Ratio (LSR) is presented. In order to quantitatively define the spatial crack propagation scenario, the involute spur gear tooth geometry cut with a typical double rounded rack is first determined using two parametric equations. The effects of some gear design parameters and initial crack locations on GMS and LSR are determined and compared with the results from previous papers that used Finite Element Analysis (FEA) in order to verify the proposed analytical model. Finally, a quasi-parabolic crack propagation scenario is assumed, in which 7 propagation cases and 3 typical crack growth paths on the tooth surface are investigated to determine their effect on the maximum reduction of GMS when compared to normal conditions. The results are important for the dynamic simulation of gear transmission behavior, and consequently helpful for the monitoring of gearbox working condition and detection of early crack damage that may exist in gear sets.