On the Computing of the Torsional Rrigidity of a Harmonic Drive Using FEA

Strain wave gearing also known as harmonic drive gearing is a mechanism commonly used in robotics. Their high reduction ratios combined with their small sizes are some of the keys that speeded their use in industrials applications. Over the last years, several research works have been carried out to determine the characteristics of strain wave gearing such as torsional stiffness, hysteresis, fatigue and efficiency. Most of these researches have been focused on testing harmonic drives at various operating conditions and by capturing their characteristics with test units using strain gage, encoder and torque meter. Today, the possibility of simulating complex problems using finite element software has brought new possibilities that allow duplicating of the behavior of highly nonlinear systems with multiple contact surfaces. The objective of this work is o develop a numerical model of a harmonic drive that replicate the torsional stiffness of an actual harmonic drive. Once validated this model will be used to study effects such as teeth engagement and teeth profile to develop a numerical model to predict the characteristics of harmonic drives under development. The ANSYS software has been used in this research to simulate the complex tooth engagement process between the flexspline and the circular spline of a harmonic drive as well as the torsional rigidity of harmonic drives. Numerical results and theoretical models in replicating the static behavior of the harmonic drive will be compared and discussed.

View Now (PDF)