Monitoring of viscous damper fluid viscosity using piezoceramic transducers—a feasibility study

The viscosity of the fluids inside a viscous damper is essential for the energy absorption and dissipation capabilities of the damper. However, service-induced changes in viscosity can significantly reduce the seismic performance of viscous dampers over time. Hence, it is necessary to develop an effective approach to monitor the viscosity of fluids in dampers. In this paper, an active sensing method to monitor the viscosity of fluids with piezoceramic transducers is proposed. Two transducers are installed inside a damper to separately function as an actuator and a sensor to respectively emit and receive vibration signals. The relationship between the viscosity of the fluids and the signal amplitude is analyzed from the perspective of the one-dimensional wave theory. A viscosity variation index (VVI) is defined to quantify the relationship between the amplitude of received signals and the fluid viscosity. Numerical results show that the VVI decreases exponentially with the increasing viscosity of the damper’s fluids. The experimental results agree well with the numerical analysis, thus validating the feasibility of the proposed approach.