Tooth Contact Stress Research Articles

Computerized design, simulation of meshing, and contact and stress analysis of face-milled formate generated spiral bevel gears

A new approach for design, tooth contact analysis (TCA) and stress analysis of formate generated spiral bevel gears is proposed. The advantage of formate generation is the higher productivity. The purposes of the proposed approach are to overcome difficulties of surface conjugation caused by formate generation, develop a low noise and stabilized bearing contact, and perform stress analysis. The approach proposed is based on application of four procedures that enable in sequence to provide a predesigned parabolic function of transmission errors with limited magnitude of maximal transmission errors, a bearing contact with reduced shift of contact caused by misalignment, and perform stress analysis based on application of Finite Element Method. The advantage of the approach developed for finite element analysis (FEA) is the automatic generation of finite element models with multi-pairs of teeth. The stress analysis is accomplished by direct application of ABAQUS. Intermediate auxiliary CAD computer programs for development of solid models are not required. The theory developed is illustrated with an example of design and computation.

Misalignment loads in splined gear couplings

Coupling misalignment results in redistributing the spline teeth load which increases the maximum tooth contact and bending stresses. The uneven tooth loads also generate tilting and friction moments that have to be transferred through the shafts to the bearings. These additional loads could significantly reduce the bearing lives if not accounted for in the bearing design. In this study, a method is presented to calculate the spline tooth load distribution, misalignment moments and the bearing reactions.

Bending Stress and Tooth Contact Stress of Cycloid Gear with Thin Rims.

Cycloid gear which was driven by three crankshafts and had three thin rims, was chosen as the subject of study. The bending stress of the rim and the tooth load of the cycloid gear were analyzed using the two-dimensional finite-element method when the gear had no machining and assembly errors and no backlash. Then the effect of the rim thickness on the bending stress and the tooth load were discussed, and the following conclusions were obtained. Both the bending stress of the rim and the tooth load are proportional to the applied torque. When the rim thickness decreases, the tooth loads decrease on the teeth located on the thin rim and increase on the teeth not on the thin rim. The ratio of the maximum tooth contact stress to the contact strength of the gear material is much larger than the ratio of the maximum bending stress amplitude on the rim to the bending strength of the gear material. Therefore, the tooth contact stress on teeth not located on the thin rim, not the bending stress, should be considered when designing cycloid gear with thin rims.

Static contact stress analysis of a spur gear tooth using the finite element method, including frictional effects

The literature available on gear tooth contact stress problems is not very extensive and that available does not explain the method by which analysis was carried out. In this paper an attempt has been made to study the contact stresses of a pair of mating gear teeth, under static conditions, by using a two-dimensional finite element method and the Lagrangian multiplier technique. The contact condition at the neighbouring node pair, namely, the contact existing over a number of node pairs in the contact zone, has been considered. To study the effect of friction between the mating gear teeth a range of average static friction coefficients, from 0.0 to 0.3, has been considered. The actual length of contact against the calculated length of contact is discussed. The variation of contact stress along the contact surface in a direction normal to the mating surfaces, which will give an idea about the depth of hardening required, is also presented.

Finite-element analysis of large spur and helical gear systems

The application of the three-dimensional finite-element substructure method has helped to improve the accuracy of calculation of gear tooth contact and fillet stresses in large spur and helical gear systems. The development of a dedicated preprocessor has reduced significantly the manual effort involved in the analysis. The methodology is explained using the example analyses of the gear systems in the two stages of a typical speed reduction gearbox used in the Pratt & Whitnev-Canada PVV100 turbopropeUer engines. n p(x) Nomenclature Al9A2,A3 = constants in the expression for the line load intensity B^B2,B3,B4 = constants in the expression for normal displacement L = length of line of contact on the tooth contact face = number of nodes along a contact line = line load intensity as a function of distance = reactive force at node / = distance along line of contact on the tooth contact face — normal displacement at node i = normal displacement distribution as a function of x

On Tooth Contact Marking and Gear Performance : 2nd Report, Gears with Harmful Tooth Form

Patterns of tooth contact marking of helical gears with pressure angle error, with pressure angle error plus alignment error, and with pressure angle error plus longitudinal crowning tooth trace correction were calculated and compared with measured patters. Measured and calculated tooth fillet stresses of these gears were also compared. The comparison showed good agreement and certified the reliability of the analyzing method for tooth contact marking and gear stress state. for tooth fillet stress, contact stress and flash temperature, the rate of increasing owing to gear error is discussed in relation with tooth bearing: When the amplitude of pressure angle error and longitudinal crowning changes, the stress increasing rate show two different characteristics, which correspond to the difference in the changing fashion of the tooth contact marking pattern. When a gear has concave tooth form error and pressure angle error, the stress increasing rate can be large in spite of a state of good tooth bearing.

Effects of Tooth Form on Stresses in Helical Gears : 1st Report, Effects of Convex and Concave Tooth Profiles

The effects of tooth form error on the stresses of helical gears are less clarified than those with spur gears. In this study, the tooth fillet stress of helical gears with convex or concave tooth profile is measured, and the effects of tooth form error on the stress are investigated by comparing with an analysis of power transmitting characteristics of cylindrical gears, which has been developed before. As a result, it is confirmed that the theoretical analysis is valid, and it makes the theoretical calculation of tooth contact stress and flash temperature more reliable. From these considerations, it is verified that the concave tooth profile is undesirable for tooth fillet stress, contact stress and flash temperature.

Strength Calculation of Large Helical Gears

A way to calculate the state of tooth fillet stress, contact stress and flash temperature on tooth flank of large helical gears with profile-, longitudinal form error and simultaneous pitch error is shown. The calculated tooth fillet stress and the contact pattern on tooth flank are compared with the values and figures measured on large double helical gears of 366000 DWT tanker ship drive during test voyage, in order to show the reliability of this calculating method. A hint is shown, to decide the order of accuracy of transverse tooth profile and longitudinal tooth form as input data for this calculation.

Reduction of the Contact Stress in Internal Gear Pumps

A method is described for calculating the tooth contact stresses in internal gear pumps, and it is shown that a considerable reduction can be achieved in the maximum contact stress by altering the proportions commonly used in existing pumps.

Rocket Motor Gear Tooth Analysis (Hertzian Contact Stresses and Times)

In this paper a rocket motor turbine-pump reduction gear system is analyzed in regard to Hertzian gear tooth contact stresses and times of contact. It is found that the Hertzian contact stresses vary from approximately 100,000 psi to 200,000 psi. The times of contact vary from three to eight microsec. Some observations regarding the correlation between contact times and gear failures are made. It is indicated that it may be possible to establish design limitations on the contact times to insure satisfactory gear operation. Sample calculations for evaluating each of the typical quantities found in the tables are included.