Snap-through response of three-dimensional braided composite panels in thermal-acoustic-aero coupled field

This paper presents a novel investigation into the snap-through response of three-dimensional (3D) fourdirectional braided composite panels subjected to aerodynamic loads generated by supersonic flow. The study introduces a unique finite element method to establish the dynamic equations of the panel. Utilizing a multi-scale approach, the thermo-acoustic and aerodynamic coupling response of simply supported 3D four-directional braided composite panels is analysed in both the time and frequency domains. The paper explains the underlying mechanism of snap-through motion using the potential well theory and introduces the concept of zerocrossing frequency for quantitative classification of snap-through motion. Notably, variations in the critical sound pressure level (SPL) due to changes in aerodynamic and acoustic loads are identified. The research reveals that when the dynamic pressure is below the critical flutter dynamic pressure, the potential well deepens, making it more difficult for panels to experience snap-through motion. Conversely, once the dynamic pressure surpasses the critical flutter dynamic pressure, persistent snap-through motion is triggered. Moreover, the aerodynamic load induces changes in the potential well, leading to a decrease in the snap-through critical SPL. These findings not only contribute to the prediction of fatigue life in braided composite panels but also have practical implications for the design of hypersonic vehicles.