A comprehensive study on Hertzian contact stress behaviour of engineering thermoplastic gears using 3D finite element analysis

Abstract

Two-dimensional Finite Element Analysis is frequently utilized to determine the behaviour of gear contact stress due to its computational time and higher efficiency. Based on the gear tooth-to-face width ratio, either plane stress or plane strain was selected in the investigations. However, the existing investigations failed to explain the above selection criteria. Thus, the present work attempted to do detailed contact stress investigations for all thermoplastic gears using 3D FEA and compared them with 2D FEA. Based on the criteria, the face widths of 5 and 20 mm were selected during the 3D analyses, replicating the plane stress and plane strain conditions of the 2D analysis. Contact stress variations with respect to face width were extracted at 10 distinct locations. For both 5 and 20 mm gears, higher contact stresses were obtained on gear edges, whereas lesser contact stresses were in the centre regions of the gear. For all the analysed thermoplastic gears, 5 and 20 mm face-width gears exhibited plane stress conditions. Subsurface and surface stress was detected during 3D and 2D analysis for both gears. For PP, the maximum contact stress occurred at the lowest depth value of 0.15–0.155 mm, and PC exhibited maximum contact stress at 0.275–0.28 mm depth. A dimensionless ratio of proportional limit – to – young’s modulus was introduced to predict the maximum contact stress depth for the thermoplastic gears. And it was observed that the ratio is directly proportional to the maximum contact stress depth value.