Abstract: In order to improve the accuracy and efficiency of tooth contact analysis of internal helical gears, an automatic modeling method of high-precision three-dimensional finite element model of internal helical gear is proposed. The dentiform normal method is applied to derive the tooth profile equations of the internal and external helical gear on the basis of the accurate description of the gear cutter. The parameterized coarse mesh finite element model of internal and external gears are established. Local multi-level refinement method of the hexahedral element has been developed to identify the element on the tooth surface in the contact region automatically to ensure the accuracy and mesh density of the gear finite element model. The tooth contact analysis was carried out, to obtain the bending stress, contact stress, contact stress distribution, transmission error, time-varying meshing stiffness as well as load sharing ratio of the helical internal gears. Comparison of the coarse mesh model with the refined mesh model indicate that the methodology proposed in this paper improves the modeling speed and calculation accuracy of the internal gears, but greatly shorten the computing time, which lays the foundation for fast and accurate internal gear tooth contact analysis.

Key words: internal helical gear, finite element model, mesh refinement, tooth contact analysis