Ultra-high-speed hybrid ceramic triboelectric bearing with real-time dynamic instability monitoring

The reliability and stability of bearing operation are crucial factors limiting the performance of high-speed rotating machinery. In this study, an ultra-high-speed hybrid ceramic rolling element triboelectric bearing (US-HCTEB) was developed to provide real-time dynamic behavior and stability monitoring. Herein, we adopted a floating rolling–sliding combination freestanding mode that ensures bearing structural integrity. Furthermore, a crown-shaped cage was employed with an opening, allowing the ceramic rolling element to be used as a dielectric material that was coupled with a sector-shaped interdigital electrode set on the bearing end cover to form a floating freestanding triboelectric nanogenerator (TENG). The rolling element self-rotated and revolved owing to the traction of the raceways, sweeping the electrodes to generate an alternating current. Additionally, the superiority and reliability of the US-HCTEB were demonstrated using a 30 million cycle durability test and an ultra-high rotating speed test at 16000 rpm, which far exceeds the capabilities of previously reported triboelectric bearings. The US-HCTEB output was then evaluated considering variable working conditions, structural optimization, and the surrounding environment. Dry contact lubrication and low humidity were found to be beneficial for the output performance. The spectra of the output current and the statistics describing the rolling element instantaneous speed suggest that the high-speed heavy radial load of the US-HCTEB could reduce overall skidding at the cost of increased instability. Subsequently, an extremely fast acceleration and deceleration test program was conducted on the US-HCTEB to evaluate its performance under the complex and nonstationary conditions in which high-speed bearings operate. The results revealed that the US-HCTEB not only achieved real-time and high-resolution dynamic behavior identification but also exhibited high reliability as it functioned appropriately until bearing failure. Thus, the proposed high-precision US-HCTEB can serve as an essential basis for the development of smart rolling bearings.