Vol-4 Issue-5 2018 IJARIIE-ISSN(O)-2395-4396 9119 www.ijariie.com 413 Comparison of Bending Stress on Circular and Elliptical Profile Fillet of Helical Gear Using AGMA and ANSYS Bhupendra Kumar Sahu 1 , Mahesh Dewangan 2 1 PG Scholar, 2 Associate Professor, 12 Department of Mechanical Engineering 12 Shri Shankaracharya Technical Camus, Shri Shankaracharya Group of Institution, Bhilai, Chhattisgarh, India Abstract Gear tends to play a very vital role in all industries for power transmission between shafts. It is a critical mechanical component in a mechanical power transmission system. A pair of helical gear generally subjected to two types of repeated load, one is bending load and another is surface load. Two types of stresses developed in helical gear pairs are: Bending stress (causing bending fatigue) and contact stress (causing contact fatigue). Both stresses act at a time at the same point of contact. If the both stresses attain their maximum value, the failure of gear occurs mainly in two distinct regions, which are tooth flank and the tooth root fillet. These types of tooth failure can be minimized or can be avoided by taking greater care during the design stage by avoiding the problem and creating a proper tooth surface profile with the better manufacturing method. This thesis reviews the methodology used to investigate bending strength of helical gear. Bending stress plays a vital role in gear design and manufacturing to reduce failure and cost. Magnitude of bending stress is controlled by the nominal bending stress and the stress concentration due to the geometrical shape. This work shows that the bending stress estimation for different shape of tooth root fillet. AGMA and ANSYS is used to estimate bending stresses at tooth root fillet and suggestion for best suited shape of tooth fillet. Keywords: Design; modelling; Helical gear; Tangential force; bending stress; root fillet; AGMA; ANSYS; FEA. I. Introduction Gear is a mechanical element which has number of teeth which is used to transmit power or motion or torque from one shaft to another shaft. Shafts may be parallel or may be at an angle. According to the shaft position different types of gears are used. Power transmission process is accomplished by successively engaging teeth. For transmitting power no intermediate link is required in gear, power is transmitted by direct contact of gear teeth. To transmit definite power or motion or torque from one disc to the other disc with any slipping between disc, projection and recesses on the disc are needed which can mesh with each other. The disc on which teeth are formed is known as gear wheels. As gear is a power transmitting element therefore gear must have sufficient strength to transmit power without any failure. Gear material as well as gear geometry highly influence the gear strength. This thesis is focused on the profile of gear teeth with most common used material to transmit high power with higher load carrying and respectively with lower weight. Failure of gear occurs when working stress exceeded the yielding/ultimate stress. It is observed that the major failure of gear is due to tooth bending fatigue, tooth-bending impact, and tooth wear. Failure of gear before life span can be avoided if greater care is taken during the design stage a sound gear design can be designed. Gear tooth generally subjected to cyclic and dynamic stress failure that are due to tooth bending fatigue, tooth-bending impact, and tooth wear. Gear tooth failures mainly occur in two distinct regions, the tooth flank, and the root fillet. The objective of this study is to estimate bending stress at root fillet using circular and elliptical root fillet and suggest best suited tooth root fillet for helical gear having better performance and strength.