Simulation of Surface Acoustic Wave Torque Sensors Using Coupling of Mode Analysis

In this work, a simulation scheme using coupling-of-mode (COM) analysis for surface acoustic wave (SAW) torque sensors is presented. To extract the COM parameters, the finite element analysis (FEA) is employed. A static study of a shaft with an applied torque is carried out so that the stress and strain field distributions on the piezoelectric substrate can be examined. Then, the simulations on a unit periodic structure of a SAW device with and without applied torques are conducted. Finally, the frequency responses of a SAW torque sensor using a P-matrix cascading technique with the COM parameters are simulated, where a good linearity between the applied torques and frequency responses is presented. The proposed method not only provides the frequency response of a SAW torque sensor, but also it allows its bias sensitivity to be evaluated.