Finite Element Analysis Of Mechanical Properties Of Bolted Thin-Walled Cylindrical Shells

Thin-walled cylindrical shell structures are widely used in various aerospace structures,and most of them are multi-cabin connections.The connection between cabins will have a greater impact on the overall mechanical properties of the structure.Common connection forms include thread connection,pin connection,glue connection,welding and so on.Thread connection is widely used because of it can be dismantled and assembled conveniently,and it also has a high reliability.Bolt connection is the most commonly used connection form in thread connection.The existence of bolted connection structure makes the interface discontinuous,and the friction contact of the connection interface will directly affect the contact characteristics of the joint surface,thereby affecting the mechanical properties of the whole structure.Therefore,it is of great significance to analyze the mechanical properties of bolted thin-walled cylindrical shells.Based on the structure of bolted thin-walled cylindrical shell,the solid finite element model,mixed finite element model and reduced finite element model are established.Then the static characteristics,natural characteristics and vibration response characteristics of the structure are studied.The main contents of this paper are as follows:(1)Based on ANSYS finite element software,the solid contact finite element model of bolted thin-walled cylindrical shell structure is established,and its static characteristics are explored.The magnitude of residual pre-tightening force and the distribution of contact pressure under different pre-tightening methods and different tightening sequences are analyzed and compared with the distribution of contact pressure measured by experiment.On this basis,the reasonable unloading mode of bolts and the influence of external load on the residual preloading force of bolts are explored.(2)On the basis of static analysis,the hybrid finite element model of the system is further established,and its natural characteristics are analyzed based on the solid contact model and hybrid finite element model.Through simulation and experiment,the natural characteristics of the system under different boundary conditions are explored.Considering the influence of bolt preload,the influence of preload on the natural characteristics of the system is studied.(3)Based on the analysis of the natural characteristics of the system,the model is linearized and modeled to obtain the linear reduced hybrid model of the structure,and the response characteristics of the system under the deterministic excitation are analyzed.In order to verify the accuracy of the model and analysis method,the sweep frequency,fixed frequency and impact experimental test of the structure are carried out,and the effectiveness of the model and simulation method are verified based on the experimental results.On this basis,we explore the conditions for linearizing the structure,and the effects of different excitation amplitudes on the response characteristics of the system are investigated.Finally,in order to further improve the computational efficiency,the derived matrix method is used to analyze the response characteristics of the linear model.(4)Based on the analysis of the deterministic response characteristics of the structure,the response characteristics of the structure under random loads are further explored.Two methods,spectral analysis and virtual excitation method,are used to analyze the structure,and the advantages and disadvantages of different methods are compared.The virtual excitation method is implemented in ANSYS finite element software based on mass method and harmonic response method to improve the solving efficiency.The influences of different loading directions and different loading modes on the structural response characteristics are also analyzed.