Semi-analytical dynamic modeling and vibration analysis of double cylindrical shell structure based on the general bolted flange model

Abstract

A general bolted flange model is proposed to improve the efficiency and applicability of the model for bolted connection shell structures. The bolted flange is taken as a sub-structure and simulated by a virtual material disk, and the disk is divided into bolt-affected region and non-bolt-affected region. The elastic modulus of the disk in the bolt-affected region obeys a specified function distribution (constant, sine and parabola distribution are adopted here, respectively) to accurately reflect the non-uniform distribution of pressure at the joint of bolts, thus forming a general model of the bolted flange. The general model not only retains the geometric features of the flange but also can be directly applied to the shell without depending on the deformation relationship between the shell and the bolted flange structure, which improves the model accuracy and efficiency. Furthermore, based on Kirchhoff plate theory and Sanders’ shell theory, the free vibration equations of the virtual material disk and the left and right cylindrical shells are derived, and then the semi-analytical dynamic model of bolted flanged double cylindrical shells is established by integrating the three substructure models. Finally, an experimental system is set up to verify the rationality of the semi-analytical dynamic model of double cylindrical shell structure based on the general bolted flange model. The effects of the number of bolts, the pre-tightening force amplitude and the non-uniform pre-tightening of bolts at adjacent positions and cross positions on the natural characteristics of double cylindrical shell structure with bolted flange connection are investigated.