Study of the influence of the type of root profile on tooth bending stresses in spur gear drives

This Master Thesis is directed to the improvement of the behavior of spur gear drives related with the second type of failure, tooth brake through bending. For doing that, a study of the influence of the type of root profile on tooth bending stresses in spur gear drives is presented. Different types of root profiles will be applied through the use of the Integrated Gear Design (IGD) software developed by the Research Group of Advanced Gear Transmissions of the Universidad Polit´ecnica de Cartagena. Standardized ISO profiles will be implemented considering types A, B, C and D of this Standard. The type of root profile that the Standard considers is a trochoid, that is a curve generated by a rounded tip of the rack-cutter tooth. Then, this conventional root profile will be substituted by three types of root profile considering elliptical, Hermite and Bezier curves. Besides the type of the root profile, the effect of their dimensions on bending stresses are also investigated by decreasing the root diameter, increasing the fillet-form diameter, or reducing the root land. Furthermore, with the same software, bending stresses will be analyzed on the root profiles, through the finite element method. Using the finite element models that are exported from IGD and using a general purpose software for finite element analysis (ABAQUS), bending stress will be compared and the appropriate conclusions will be drawn.