Research On Stability Analysis Method Of Crane Jib Structure With Flexible Support

With the development of technology and economic growth in our country,more and more large-scale projects are being built.The actual demand of engineering application determines the direction of crane’s large lifting capacity and large working range.The jib of lattice structure was developing to large and soft,and its stability analysis and checking is especially important.The single waist rope structure can reduce the jib deflection,enhance the overall stability,but the effect of load’s and deadweight’s axial force makes out-of-plane stability very complicated,and there is no analytical buckling characteristic equation to be used,and solution still rely on finite element software.On the other hand,there are still some shortcomings in the analysis method of in-plane stability of double suspension horizontal jib,and the mechanical model was not accurate enough.It is necessary to remodel and summarize the method of in-plane stability analysis.First,in view of the problem of finite element software: different structure modeling,difficult to obtain analytic solution or analytic expression,the divide number of elements was not clear with accuracy require,it started from the finite element equation,compared with the classical Euler analysis method,explained error sources of finite element approximation,and summarized the accuracy control method of approximate finite element equations in application.Based on theory of Ⅱ order,using differential equation method,the out-of-plane buckling characteristic equation of single and double waist rope jib structure was inferred,and the recurrence relation of the out-of-plane buckling characteristic equation of multi waist rope jib structure was summed up;it obtained the out-of-plane buckling characteristic equation of single waist rope horizontal jib structure,single rod horizontal jib structure,double rod horizontal jib structure,and the out-of-plane stability of different structures was compared;The influence of waist rope structure parameters on out-of-plane stability of single waist rope horizontal jib was analyzed,and optimization design method of structural parameters was brought up.Considering the uniformly distributed load of deadweight in the axial direction of the jib,based on exact finite element theory of beam element considering theory of ⅱ order,the out-of-plane buckling characteristic equation considering deadweight of single and multi waist rope non-horizontal jib structure was inferred.Possible structural variations and buckling forms under different working conditions of double rod horizontal jib was classified,and using exact equivalent model with elastic support,in-plane buckling characteristic equations under various buckling modes was deduced,and analysis and calculation method of structural buckling judgment by double rod’s axial force was summarized;In-plane buckling characteristic equation of single waist rope horizontal jib structure was deduc ed too.This paper started with the defect of approximate finite element method and the necessity of classical analytic method,studied and perfected stability of crane jib structure with flexible support,and provided analytical expressions.It provides theoretical support for further research in this field,and has guiding significance for engineering practice.