A hybrid triboelectric-piezoelectric smart squirrel cage with self-sensing and self-powering capabilities

In aero-engines, squirrel cages are commonly used as elastic support parts for bearings, serving to adjust critical speeds and provide vibration damping. Their stable operation is critical for the safety and stability of rotor systems. In this paper, a triboelectric-piezoelectric squirrel cage (TPSC) with self-sensing and self-powering capabilities is proposed. Owing to the ingenious utilization of the supporting structure, a compact design is achieved, enabling energy harvesting from the relative motion of the rotor-stator structure and the vibration of elastic support. Based on a fabricated prototype, a series of experiments are carried out to investigate the effect of the rotating speed, imbalance mass, and contact mode on the output performance of TPSC. Under the rotating frequency of 15Hz, a maximum power output of 100.0 μW is achieved. The TPSC is capable of sensing rotating speed and detecting rolling bearing faults. A self-powered temperature and humidity sensing system that can transmit data wirelessly every 10minutes is also realized. The TPSC enables self-powered monitoring of rotor bearing systems with squirrel cages, providing a new option for online condition monitoring of aero-engines.