A mathematical model for analyzing the vibration characteristics of fiber-reinforced thin-walled conical-cylinder composite shells with local bolt missing by the artificial spring method

This paper explores the vibration characteristics of fiber-reinforced thin-walled conical-cylinder composite shells (FTCCS1) with local bolt missing connections by combining theory and experiment. Firstly, based on the classical lamination theory and Kirchhoff-Love assumption, the FTCCS with local bolt missing is modeled. In order to simulate the bolt connections, the artificial spring method is used to equivalently represent any boundary conditions at the joints, where the artificial spring is divided into two forms: main spring and sub-spring. Meanwhile, the orthogonal polynomial method, Rayleigh-Ritz method, and modal superposition method are used to solve the vibration characteristics of the FTCCS with local bolt missing. To verify the rationality of the model, TC300/epoxy resin-based the FTCCS are taken as the research object, and vibration tests such as impulse, sweep, and resonance excitation are carried out. The experimental results show that the errors between the natural frequency and response displacement calculated by the solving method and the test results are in the range of 0.66 %similar to 4.56 % and 0.26 %similar to 10.39 %, indicating the reliability of the mathematical model prediction. Finally, by changing the bolt connection status, the structural dynamic parameters under different conditions are calculated to evaluate the impact of complex bolt connections on the vibration characteristics of the composite shell.