Non-uniform elastic constraint modeling and stiffness identification for the bolted thin-walled cylindrical shell

To simulate the actual constraint condition, a novel non-uniform elastic constraint model with continuous stiffness variation and independent stiffness distribution is presented for dynamic modeling of the bolted thinwalled cylindrical shell. By combining the Marine Predators Algorithm, Genetic Algorithm, and modal shape recognition strategy, an accurate and efficient inverse identification method is developed to identify the constraint stiffness coefficients, based on the finite element models with bolt connections and non-uniform elastic constraint. Good agreement between the numerical and experimental results validates the correctness and effectiveness of the non-uniform elastic constraint model and its inverse identification method. The impacts of bolt number, stiffness coefficients and stiffness detuning on vibration characteristics of the shell with nonuniform elastic constraint are investigated. Results show that the parity of bolt number would change its impact pattern on natural frequencies, and the natural frequencies corresponding to lower circumferential wave numbers are more sensitive to the variation of stiffness coefficients. Increasing the bolt number can effectively reduce the sensitivity of vibration characteristics to the stiffness detuning of bolt connections, but large-scale stiffness detuning of bolt connections should be avoided especially when the number of bolts is large.