Internal vacuum detection of hollow structures based on modal analysis

Hollow structures are increasingly being adopted for load-bearing and critical components in advanced aircraft and power devices, owing to their advantages of light weight and high strength. In this research, an innovative approach has been developed for determining the vacuum level inside hollow plates through the application of modal analysis techniques. The structure's geometric model was imported into the COMSOL finite element software for simulation and analysis, where the pressure of the internal air material was varied to simulate different vacuum environments. The simulation results indicate that there is a coupling phenomenon between the acoustic pressure modes within the hollow structure's cavity and the vibration modes of the structure's solid part. Moreover, the internal air pressure exerts a significant modulating effect on these characteristics. When a harmonic load is applied near the fixed constraint end of the structure, the amplitude ratio of the structure's second-order resonance is negatively correlated with the internal cavity air pressure.