Finite Element Analysis of High Contact Ratio Spur Gears in Mesh

Abstract

High contact ratio gears have been demonstrated to provide significant advantages for decreasing tooth root and contact stresses with potential flow-on benefits for increased load carrying capacity. Previous investigations with high contact ratio gears have involved analytical, numerical and experimental aspects. Much of the earlier numerical work using FEA was limited in its usefulness due to several factors; (i) the difficulty in predicting load sharing over roll angles covering two or three teeth simultaneously in mesh, (ii) the difficulty for the analysis to obtain quality results when modelling Hertzian contact deflection simultaneously with the bending, shear and angular deflections, and (iii) the problem of primary unconstrained body motion when (long) profile modifications were applied. This paper presents methods and results for overcoming these difficulties with recent computer hardware and software improvements. Particular developments discussed include the use of FE analysis of High Contact Ratio Gears in mesh and the results obtained when adaptive meshing is used. The details of transmission error, combined torsional mesh stiffness, load-sharing ratio, contact stress and tooth root stress against various input loads over a complete mesh cycle are also given. Results with various tooth profile modifications are presented and comparisons between the results show evidence for the optimal profile modification expected to gain the maximum benefit of HCRG.