Comparison of Spur Gear Root Stress Calculations

Abstract

Methods of Spur Gear Root Stress determination were analyzed by comparing an experimentally proven method to documented theoretical methods. The methods evaluated were German DIN standards, AGMA standard, JGMA standard, and Cornell method. The Cornell method was used as a benchmark for comparison of other methods. Each method was used to calculate root stresses in a spur gear system. The gear system variables were torque and rotational speed. Seven different torque settings and four different rotational speeds were used in the analysis, giving 28 different system settings for analysis. The system was modeled using a NASA computer program, Dynamic Analysis of Spur Gear Transmission (DANST) developed by one of the authors. The stresses in the tooth root were calculated from the dynamic forces at 121 points along the involute tooth profile during a two-gear mesh. The study has shown that the stresses calculated using AGMA could predict the stresses calculated using the Cornell method of stress calculation. The JGMA method calculates the maximum root stress of the gear system within three percent of the Cornell method. The study showed that AGMA, and JGMA methods could be as effective at calculating the root stresses as the Cornell method.