基于ANSYS的人字架的优化设计英文参考文献

Investigations On Gear Tooth Surface And Bulk

Temperatures Using ANSYS

P R Thyla

PSG College of Technology, Coimbatore, INDIA

R Rudramoorthy

PSG College of Technology, Coimbatore, INDIA

Abstract

In gears, the temperature at the conjunction zone between the meshing tooth faces governs the imminent scuffing failure. Failure due to high tooth temperatures can be prevented with the knowledge of temperature distribution in gear teeth under operation. In this work, the prediction of bulk and surface temperatures of the gear tooth is carried out using finite element method, using ANSYS. The investigations are carried out on the tooth of the worm wheel of different sizes of single reduction worm gear boxes under various operating conditions

Introduction

Conventional gear designs are based on the bending and surface fatigue failure criteria. Failure due to bending is avoided by ensuring in the design that the maximum bending stress in the tooth is lesser than the bending strength of the material. Limiting the Hertzian contact stress induced in the gear tooth to be below the contact compressive strength of the gear material ensures safety in respect of surface fatigue. Dynamic load factors are included in the design to account for effects due to dynamic loading. But these designs do not consider the thermal behaviour of the gears. But in gears that are operated at high speeds and loads, temperature can be of concern and may be a limiting factor. Also, in worm gear drives, due to the large amount of heat generated due sliding friction, temperatures may exceed safe limits during operation. Hence, for gear drives that operate at high speeds and under heavy loads, and in worm gear drives in which the amount of heat generated due to sliding friction is more, it is essential to know the thermal behaviour of the drives at the design stage itself so as to know safe limits of load and speed.

Procedure

In this work, finite element thermal analysis is carried out on a tooth of the worm wheel to predict the temperature distribution in the tooth. The problem of determining the bulk temperature is considered as a steady-state heat transfer problem in which a state of thermal equilibrium is reached after many cycles of revolution. In order to predict the bulk and the surface temperatures of the gear tooth, a single gear tooth of the worm gear is modeled using UNWINS method of involute profile generation and the solid model generated by coordinate transformation. The reason for modeling a single gear tooth is that the gear tooth is symmetrical in shape and identical heat generation occurs in all the teeth of the gear. The solid model of the tooth of the worm wheel is discretised using 3D, 10-noded tetrahedral elements, ie., SOLID87 element. The finite element mesh of the gear tooth is shown in Figure 1. A convergence test was carried out, by varying the element size so as to ensure correctness of mesh density. The results of the test is depicted in Figure 2.