Method of calculation and test of dynamic tooth root strain for high-contact-ratio spur gears

ObjectiveAiming at the difference of load sharing and dynamic characteristics between high-contact-ratio spur gears and conventional spur gears, a method for calculating the dynamic tooth root strain was proposed considering the dynamic characteristics of the gear system.MethodsA dynamic model of the gear system was established with the lumped-mass method, and the dynamic meshing force was calculated by using the Newmark-<italic>β</italic> method to solve the system dynamics equations. The dynamic analysis model of gear structure was established by the finite element method, the load sharing between gear teeth was determined with the loaded tooth contact analysis method, and the time history of tooth root strain was calculated by the transient analysis method. The dynamic tooth root strain of the high-contact-ratio spur gear under different input speeds and torques was solved by using the proposed method, and the calculated results were compared with the conventional spur gear.ResultsThe results indicate that the load sharing rate of the single tooth pair of high-contact-ratio spur gear is between 0.2 and 0.6, and the tooth root strain of high-contact-ratio spur gear increases and then decreases twice respectively. The peak value of tooth root strain of high-contact-ratio spur gear increases with the increase of input speed and torque, and the peak value of the tooth root strain of high-contact-ratio spur gear is obviously lower than that of conventional spur gears under different working conditions. The dynamic tooth root strain of high-contact-ratio spur gear obtained by the method was compared with the test results. The relative error between the peak value of the tooth root strain and the measured results is less than 10%, which verifies the validity of the calculation method.