A low-frequency longitudinal vibration transducer with a helical slot structure.

In this paper, the authors design a longitudinal vibration transducer with a low resonance frequency and a large longitudinal amplitude by carving helical slots on the surface of the hollow cylinder front mass. The resonance frequency of the transducer is calculated by frequency equations obtained from the equivalent circuit of the transducer. A finite element model (FEM) of the transducer is set up, and it is used to compute the admittance and the longitudinal vibration amplitude of the transducer. The influences of the slot number, the width of the slot, the number of spires of the spring, and the helix pitch on the performance of the transducer are analyzed by numerical simulation. The simulation results show that the resonance frequency of the transducer with helical slots is much lower than that of the transducer without slots. A prototype transducer with helical slots is constructed, and the admittance and longitudinal vibration amplitude are measured experimentally. The measured resonance frequency of the transducer is in good agreement with the simulation results. The measured longitudinal vibration amplitude is lower than that computed by the FEM, which may be due to the damping of the materials.