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Bolt connection is commonly used to assemble shell structures in engineering fields. Prolonged external excitation can induce stick, slip, even separation states at the connection interface, leading to complex nonlinear dynamics in bolted shell structures. Understanding the dynamic mechanism of bolted joined shells under stick–slip-separation condition is crucial for the design and application of these structures. In this study, we aim to build the nonlinear dynamic model and reveal the vibration mechanism of bolted joined conical-cylindrical shells with stick–slip-separation behavior. During the development of the mechanical model of the bolt connection, the axial bilinear stiffness characteristics and interface friction behaviors are taken into account simultaneously, which could simulate the transition of the contact state at the connection interface. The rigid joint between the conical and cylindrical shells is realized via successive distributed artificial springs. Donnell's shell theory as well as the displacement assumption of Chebyshev polynomials are employed in theoretical modeling, and the governing equation is obtained by the Lagrange equation. In contrast with existing research and experimental data, the accuracy of the present theoretical model is validated. Both theoretical and experimental results indicate the frequency multiplication and dynamic softening phenomena as the excitation level increases. By the consideration of the stick-slip-separation behavior at the connection interface in the modeling, these nonlinear vibration behaviors can be effectively illustrated. Additionally, hysteresis characteristics are further investigated to explore frictional energy dissipation. The stick–slip-separation contact state at the connection interface under different excitation levels, bolt preloads and cone angles are also analyzed. The present investigation provides a basis for the design and health condition monitoring of bolted shell structures. [ABSTRACT FROM AUTHOR]

• Nonlinear dynamics of bolted JCCSs are studied theoretically and experimentally. • Displacement-dependent characteristics in bolt connection zone are considered. • The developed model is capable of predicting nonlinear vibration of bolted JCCSs. • Experimental results validate the present theoretical model. This paper investigates the nonlinear dynamic characteristics of joined conical-cylindrical shells (JCCSs) with bolt connection for the first time. In the process of developing mechanical model of the bolt connection, the displacement-dependent stiffness and damping are taken into account, which could simulate the change of the contact state at the connection interface under different excitations. Both theoretical and experimental studies are performed to illustrate the nonlinear vibration behaviors of the bolted JCCSs. Successive uniform distributed artificial springs between the conical and cylindrical shells are adopted to simulate the rigid joint of the two shells. Donnell's shell theory is employed in theoretical modeling, and the governing equation is obtained by the Lagrange equation. The displacement admissible function applied in the research is Chebyshev polynomial. By comparison with existing literature and experimental data, the accuracy of present theoretical model is validated. It is found that both theory and experiment show a dynamic softening phenomenon with the increase of excitation level. Taking the displacement-dependent characteristics in bolt connection zone into consideration can effectively illustrate this soft phenomenon. The established model is capable of predicting the nonlinear vibration characteristics of JCCSs with bolt connection. [Display omitted] [ABSTRACT FROM AUTHOR]

• Vibrations of JCCSs with bolt loosening boundary are studied theoretically and experimentally. • Non-uniform arc constraint is established to simulate the bolt loosening boundary. • The developed model is reliable in estimating the dynamic behaviors of bolted JCCSs with different loosening degrees. • Experimental results validate the present theoretical model. This paper investigated the vibration characteristics of joined conical-cylindrical shells (JCCSs) with bolt loosening boundary conditions both theoretically and experimentally. The non-uniform arc constraint model is established to simulate the bolt loosening boundary conditions by the artificial spring technology, which can describe the actual bolt contact pressure distribution. Continuously distributed artificial springs are introduced to realize the connection of the conical and cylindrical shells. Donnell's shell theory and Chebyshev polynomials are adopted to establish the theoretical model, and the dynamic equation is derived from the Lagrange equation. The validity of the present model is verified by the available literature, hammer test and vibration shaker test. The results indicate that the maximum errors of natural frequencies and resonant displacements are less than 4.41% and 18.6%, respectively. It is found that bolt loosening has a significant effect on the fundamental frequency, but it gradually weakens with the increase of the mode order. Increasing bolt loosening degree can lead to an increment of resonant displacement. The developed model is reliable in estimating the dynamic behaviors of bolted JCCSs with different loosening degrees, and it contributes to providing guidance in the design and service process of combined shell structures. [ABSTRACT FROM AUTHOR]

• A universal theoretical model for bolted joint plates is established. • The flange effect is considered. • Theoretical results are improved by considering the pressure distribution in BJAR. • Experimental results validate the present theoretical model. The bolted joint multi-plate structures are widely used in practical engineering, but their theoretical dynamic model is hard to find in literature. The main purpose of this paper is to establish a general dynamic model of bolted joint multi-plate structures with flanges, and to investigate its vibration characteristics from both theoretical and experimental aspects. Both the flange effect and contact pressure distribution in the bolted joint affected region (BJAR) are considered. Artificial spring sets with variable stiffness are adopted to simulate the non-uniform distributed contact pressure in BJAR. The governing equations are derived based on the Kirchhoff plate theory and Euler-Bernoulli beam theory. The Chebyshev polynomials are used as admissible displacement functions. Then, the free vibration and forced vibration under base excitation are solved by means of the Rayleigh-Ritz method and Newmark-beta method, respectively. The experimental studies, including modal test and vibration response test, are conducted on a bolted joint two-plate specimen to verify the accuracy of the theoretical model. Results show that the present model is capable of realizing reliable vibration prediction and can be conveniently extended to the structure with an arbitrary number of plates and bolts. For the bolted structures, considering the pressure distribution in the connection interfaces can significantly improve the accuracy of theoretical results. [Display omitted] [ABSTRACT FROM AUTHOR]