Subsurface damage detection and prediction of thin-walled complex curved-surface component

The hemispherical resonant gyroscope (HRG), distinguished by its simple structure, high reliability, and remarkable precision, stands out as one of the most promising high-performance inertial navigation devices in advanced equipment. However, the core sensitive component of the HRG, known as the hemispherical resonator (HSR), with a complex and small curvature structure made of fused silica, experiences subsurface damage (SSD) during the grinding process. This not only leads to brittle fracture, which significantly hampers the polishing efficiency of the component but also affects the operational performance of the gyroscope. This study was initiated by quantitatively characterizing the SSD of various structural features of the HSR, including the center rod, lip edge, and spherical shell. Especially, for the curved-surface of the HSR, the average deviation of SSD detection result was within 6%. Subsequently, based on the characterized SSD, the grinding damage mechanisms of the HSR were explored. The grinding surface integrity of the spherical shell was then elucidated from the perspective of grinding stiffness and a theoretical model of subsurface damage (SSD) is derived. Finally, a predictive model for the SSD depth of the HSR after ultra-precision grinding was established according to the nonlinear relationship between the surface roughness and SSD depth. Furthermore, the maximum height of the grinding surface (Sz) could be used to further characterize the SSD depth of the ground surface for the HSR, showing a high level of predictive accuracy. This work fills the blank in SSD detection of the HSR, laying a theoretical foundation for the high-performance manufacturing of the HSR.