An Experimental and FE Analysis of Helical Gear for Bending Stress at Critical Section

The increasing demand for quiet power transmission in machines, vehicles and generators has created a growing demand for a more precise analysis of the characteristics of gear systems. In addition, the success in engine noise reduction promotes the production of quieter gear pairs for further noise reduction. In the process of gear design, the pressure angle of gear plays a vital role. It is because pressure angle simultaneously affects the base circle radius of the involutes profile and the minimum number of teeth to avoid interference varies with pressure angle. Moreover, the Lewis form factor used in Lewis equation to account for bending stress at tooth root depends upon the number of teeth and pressure angle. Higher value of pressure angle has greater length of contact, whereas smaller value of pressure angle gives quietness in operation. Nowadays, a trend is followed in using different pressure angles at driving and costal side of gear tooth. The work involves experimentation using strain gauge and 3D photoelasticity techniques to study the effect of pressure angle on bending stress at critical section of helical gear. The results obtained from the experimental analysis have been compared with theoretical and finite element method results.