Study on the influence of recurring shear components on the local tooth root load carrying capacity of helical gears

 

Starting Situation

The use of spur gears is characterized by an increasing proportion of stress cycles in thrust operation, for example during recuperation in hybrid vehicles or in hoists and pumped storage power plants. The influence of an alternating load in the tooth root by a direct load sequence of tensile and shear cycles on the load carrying capacity has already been investigated on spur and helical gears. Differences in the flexural fatigue strength of spur and helical gears of up to 10 % at pure alternating load were found. A consideration of the frequency and length of shear load cycles was analyzed in stitch tests in the pulsator test on spur gears. The influence on the tooth root load bearing capacity of helical gears, especially in the running test, is currently unknown, as no test results are available for this case so far. However, the topic is highly relevant e.g. due to the electrification effort and requires quick answers.

Research Objective

The aim of the project is to classify the influence of shear load change proportions with regard to cycle length and frequency on the tooth root load carrying capacity of spur and helical gears. On the basis of the results, an estimation can be made in practice as to when shear load changes in the load collective analysis must be considered for the load capacity calculation and whether an extended local calculation procedure is required.