Study On Vibration Characteristics And Parameter Identification Of Short Cable

With the popularization and application of the structure of cable space,cable structure in the civil engineering industry more and more appear,and also get more and more attention.The cable force test and the parameter identification problem of the cable structure need to be solved better,including the identification of cable force,bending stiffness,boundary condition and so on.At present,the cable force identification accuracy of the long cable has reached a high level,because the long cable is affected by the bending stiffness and the boundary condition,and the error is not large in most cases.But for the short coarse cable,or cable force smaller cable,bending stiffness and boundary conditions of the impact is very large,if ignored will cause great error.At the present stage,there is no reasonable calculation formula of cable force with reasonable range and high precision for the cable with bending rigidity under complex boundary conditions.The problem of parameter identification of cable structure is not well solved.Based on the above problems,the main work of this thesis is as follows:(1)Based on the vertical vibration equilibrium equation of the cable in the plane,the general solution of the frequency equation is deduced under the vibration model of the general boundary condition.The transcendental equation is solved,and the results of the frequency equation are fitted by curve fitting.Then the practical formulas for calculating the cable force are put forward.The formula has the advantages of high precision,simple form and convenient calculation,and can be used to calculate the flexural rigidity of the cable,which can be used as the practical reference.(2)according to the calculation formula of cable force proposed in this paper,the method of cable parameter identification under special boundary conditions is proposed.Find out the influence of the parameters on the n-T_n curve under the general boundary condition,and then propose the parameter identification method of the cable.The principle is to keep the cable's n-T_n curve.(3)Combining the principle of the mode node method,and using the finite element model to verify the accuracy of the vibration node method.On the basis of the cable force calculation formula introduced in this paper,the problem of parameter identification is discussed.When the measured frequencies are two and above,the identification of the cable force and the bending stiffness can be solved well.But for the identification of boundary conditions,the current can only be done to avoid its impact,but can not identify it.(4)Because of the inevitable error of analytic method,we can use the idea of intelligent search to put forward a more accurate cable force calculation method.In this paper,we first propose a matrix analysis method,which can obtain accurate natural frequency by known cable force,bending stiffness,boundary condition and so on.Then combined with particle swarm optimization algorithm to identify the parameters of cable structure.The method is more accurate,faster,wider range of applications.