Dynamic Stability Analysis Of Complex Truss Structure And Its Application In Engineering

The complex structure composed of beams and poles is widely used in construction,civil engineering,machinery,aerospace and other projects,such as the boom of crane,space launch tower,transmission tower,steel structure bridge,etc.Therefore,the stability of the truss structure is one of the key problems of structural safety.In engineering practice,the complex bar system structure often bears both static load and dynamic load.It is not reliable to design the structure only based on the results of static stability analysis.In this paper,the complex truss structure is taken as the research object.According to different boundary constraints and structural forms of the truss structure,the finite element method and energy method are used to study the dynamic stability of the complex truss structure under the periodic load.The parametric vibration problem.The new idea of the dynamic stability analysis of the arbitrary shaped truss structure under the periodic load is also explored Road.(1)Based on the finite element method,the parametric vibration equation of multi-stage stepped column with elastic support and solid support is established under the action of axial periodic load,the critical frequency equations of damped and undamped multistage columns are derived.Using Mathematica software to write a program for numerical solution,and use MATLAB soft draw parameter vibration curve.The dynamic stability of the crane's telescopic boom in and out of the lifting plane is studied,the influence of damping on the stability of telescopic boom is discussed.The analysis results show that: Under the action of axial periodic load,the telescopic boom can produce parameter vibration simultaneously in and out of the plane,the dynamic instability region of the structure decreases with the increase of damping.(2)Using the energy method,the kinetic energy,potential energy and damping potential energy of the multi-stage column under different constraint conditions are deduced.Combining Hamilton principle,the critical frequency equation of multistage column is obtained,the critical force of instability and the natural frequency of free vibration are given.A typical telescopic boom of a construction crane is taken as an example for parameter vibration analysis,the influence of damping coefficient and stiffness constraint coefficient on dynamic instability is discussed.The analysis results show that: the size of the dynamic instability zone varies with the stiffness constraint coefficient,the dynamic instability region decreases with the increase of stiffness constraint coefficient.When the constraint coefficient exceeds a certain value,the structure is close to the solid support,and the dynamic instability region will not change.(3)Based on the above research,by studying the essence of parametric vibration equation and the meaning of each symbol,it's proposed that finite element software is directly applied to analyze the static instability critical force and natural frequency of any complex truss structure,a new method for the establishment of parametric vibration equations for complex bar structures with arbitrary shapes.Through example analysis,it is shown that: The new method for vibration analysis of arbitrary complex bar structure is correct.At the same time,the dynamic stability of complex lattice members with different length and thickness ratios is studied,The analysis results show that: the dynamic instability region decreases with the decrease of slenderness ratio.In this paper,finite element method and energy method are used to analyze the vibration problem of multi-step column structure,It also provides new ideas and methods for the analysis of dynamic stability of complex truss structures,the research results provide the theoretical basis for practical engineering design and have important theoretical significance and practical value.