Bolt connection is one of the main fixing methods of cylindrical shell structures.A typical bolted connection model is considered as a tuned system.However,in the actual working conditions,due to the manufacturing err...Bolt connection is one of the main fixing methods of cylindrical shell structures.A typical bolted connection model is considered as a tuned system.However,in the actual working conditions,due to the manufacturing error,installation error and uneven materials of bolts,there are always random errors between different bolts.To investigate the influence of non-uniform parameters of bolt joint,including the stiffness and the distribution position,on frequency complexity characteristics of cylindrical shell through a statistical method is the main aim of this paper.The bolted joints considered here were simplified as a series of springs with random features.The vibration equation of the bolted joined cylindrical shell was derived based on Sanders’thin shell theory.The Monte Carlo simulation and statistical theory were applied to the statistical analysis of mode characteristics of the system.First,the frequency and mode shape of the tuned system were investigated and compared with FEM.Then,the effect of the random distribution and the random constraint stiffness of the bolts on the frequency and mode shape were studied.And the statistical analysis on the natural frequencies was evaluated for different mistuned levels.And some special cases were presented to help understand the effect of random mistuning.This research introduces random theory into the modeling of bolted joints and proposes a reference result to interpret the complexity of the modal characteristics of cylindrical shells with non-uniform parameters of bolt joints.展开更多
This study derived a novel computation algorithm for a mechanical system with multiple friction contact interfaces that is well-suited to the investigation of nonlinear mode characteristic of a coupling system.The pro...This study derived a novel computation algorithm for a mechanical system with multiple friction contact interfaces that is well-suited to the investigation of nonlinear mode characteristic of a coupling system.The procedure uses the incremental harmonic balance method to obtain the nonlinear parameters of the contact interface.Thereafter,the computed nonlinear parameters are applied to rebuild the matrices of the coupling system,which can be easily solved to calculate the nonlinear mode characteristics by standard iterative solvers.Lastly,the derived method is applied to a cycle symmetry system,which represents a shaft–disk–blade system subjected to dry friction.Moreover,this study analyzed the effects of the tuned and mistuned contact features on the nonlinear mode characteristics.Numerical results prove that the proposed method is particularly suitable for the study of nonlinear characteristics in such nonlinear systems.展开更多
基金Supported by Anhui Provincial Natural Science Foundation of China (Grant No.2108085QE223)Universities Natural Science Research Project of Anhui Province of China (Grant No.KJ2021A0156)National Natural Science Foundation of China (Grant Nos.52075086,52205078)。
文摘Bolt connection is one of the main fixing methods of cylindrical shell structures.A typical bolted connection model is considered as a tuned system.However,in the actual working conditions,due to the manufacturing error,installation error and uneven materials of bolts,there are always random errors between different bolts.To investigate the influence of non-uniform parameters of bolt joint,including the stiffness and the distribution position,on frequency complexity characteristics of cylindrical shell through a statistical method is the main aim of this paper.The bolted joints considered here were simplified as a series of springs with random features.The vibration equation of the bolted joined cylindrical shell was derived based on Sanders’thin shell theory.The Monte Carlo simulation and statistical theory were applied to the statistical analysis of mode characteristics of the system.First,the frequency and mode shape of the tuned system were investigated and compared with FEM.Then,the effect of the random distribution and the random constraint stiffness of the bolts on the frequency and mode shape were studied.And the statistical analysis on the natural frequencies was evaluated for different mistuned levels.And some special cases were presented to help understand the effect of random mistuning.This research introduces random theory into the modeling of bolted joints and proposes a reference result to interpret the complexity of the modal characteristics of cylindrical shells with non-uniform parameters of bolt joints.
基金This research was supported by the National Natural Science Foundation of China(Grant No.51575093)the Fundamental Research Funds for the Central Universities(Grant Nos.N180313008,N170308028,and N170302001)。
文摘This study derived a novel computation algorithm for a mechanical system with multiple friction contact interfaces that is well-suited to the investigation of nonlinear mode characteristic of a coupling system.The procedure uses the incremental harmonic balance method to obtain the nonlinear parameters of the contact interface.Thereafter,the computed nonlinear parameters are applied to rebuild the matrices of the coupling system,which can be easily solved to calculate the nonlinear mode characteristics by standard iterative solvers.Lastly,the derived method is applied to a cycle symmetry system,which represents a shaft–disk–blade system subjected to dry friction.Moreover,this study analyzed the effects of the tuned and mistuned contact features on the nonlinear mode characteristics.Numerical results prove that the proposed method is particularly suitable for the study of nonlinear characteristics in such nonlinear systems.
