Research On Dynamic Characteristics Of Laminated Composite Thin-walled Cylindrical Shells With Elastic Boundary Conditions

As a high-precision power machine,the aero-engine directly affects the performance of the aircraft and is the key to ensuring the reliable operation of the aero-engine.As the core components of aero-engines and gas turbines,critical structures such as casings and combination drums are subject to much higher inertial forces,aerodynamic forces,torque and complex vibration loads than conventional components,with extremely high rotating speeds.Therefore,it is not difficult to find out that the structure and performance of thin-walled cylindrical shells affect the performance and reliability of the maj or mechanical equipment such as aero-engines and gas turbines,especially in the field of structural vibration,requiring no risk of exceeding a minimum probability.Therefore,it is an urgent challenge to suppress the large vibration of the thin-walled cylindrical shell structure,reduce the vibration risk of the combined cylindrical shell structure,and improve the structural life.The vibration of the unit is drastically increased,which affects the service life of the part.In this paper,the drum rotor in the aero-engine compressor is taken as the research object.The model abstraction is used to establish a single composite laminated thin-walled cylindrical shell with arbitrary boundary conditions and its dynamic characteristics with isotropic shells.The main research work is carried out as follows:(1)Firstly,based on the Donnell thin shell theory,the nonlinear differential shell equation is used to derive the vibration differential equation of cylindrical shell.The orthogonal polynomials are chosen as the admissible displacement functions of the laminated thin-walled cylindrical shell structure with arbitrary boundary conditions.The function,compared with the classical literature,verifies the method in this study;Some examples are taken to test the convergence of the calculation and proposes a time-saving simplification principle for nonlinear terms.At the same time,attention is paid to the influence of boundary support stiffness on large vibration response;and with the non-classical boundary conditions,the influence of geometric parameters and lamination schemes on geometric nonlinear response is studied.(2)After that.considering the engineering practice,the influence of the rotating speed is introduced on the basis of previous research,and the dynamic model of the laminated rotating thin-walled cylindrical shell structure is established,focusing on the rotating speed and geometric parameters with the non-classical boundary conditions.The influence of parameters and lamination schemes on the geometric nonlinear vibration response of composite laminated thin-walled cylindrical shells.(3)Finally,considering the matching condition of two cylindrical shells and the spring support at both ends to simulate arbitrary boundary conditions.The dynamic model of the isotropic single layer-composite laminated cylindrical shell structure with arbitrary boundary conditions is established.With the finite element software ANSYS,the results are compared to verify the correctness of the proposed method.At the same time,attention is paid to the preassigned matching stiffness coefficient,the length ratio of the isotropic single-layer cylindrical shell,and the influence of the thickness of the inner and outer layers on the natural vibration characteristics of the isotropic single-layer laminated composite thin-walled cylindrical shell.