Overall Stability And Nonlinear Analysis Of Crane Space Structure With Large Flexibility

The rapid development of the national economy has led to an ever-increasing number of construction projects.Cranes have met the needs of large projects such as nuclear power,wind power,and urbanization due to their enormous upgrading capabilities.They have been favored by construction and construction parties in recent years.The use of a large tower crane,crawler cranes,and all-terrain cranes for the use of complex spacecombined boom structures has become more widespread,but the consequent difficulties in design analysis of structural stability appear.In the past,the stability calculation of the crane structure was mostly limited to the component level.The design and technical personnel only conducted a single-arm structure and single-limb stability check,neglecting the overall structural stability analysis of the entire combined boom system.For the subsequent use of lifting machinery has laid great hidden dangers.Moreover,the calculation and analysis of large complex beam systems represented by cranes often rely on finite element analysis software,which is not only limited by hard and software conditions,but also generates expensive economic and time costs,delaying the development of new products.This paper focuses on the study of the overall stability of a variety of large flexibility space combined boom structures.From the angle of analytical calculation,it provides a method and idea for the design personnel of the crane industry to analyze the stability of the complex combined boom quickly.In this paper,firstly,the polyline beam structure is introduced.Based on the secondorder theory,with effective deformation coordination conditions and boundary conditions,the in-plane stability calculation method and formula are proposed using the fourth-order differential equation calculation method.At the same time,based on the equivalent length method and the equivalent moment of inertia method,an equivalent idea that the polyline beam structure is equivalent to the multi-segment vertical cantilever beam is proposed.It is convenient to use the conclusion of the design specification of tower crane to check the in-plane stability of polyline beam structure.In this paper,the overall out-of-plane stability of jib structures are calculated for three different large crawler cranes respectively are single-main boom crawler crane,fixed auxiliary-arm crawler crane and tower jib crawler crane.Considering the influence of the non-conservative force of the cable on the force and stability of the jib structure,a reasonable force analysis is performed on the structure.Using the second-order nonlinear theory of small displacements and reasonable boundary conditions and deformation coordination conditions,several second-order differential equations are written for each jib.The buckling characteristic equation for the overall out-of-plane stability of different jib structures is obtained.The results are verified and compared with the finite element method.Considering the influence of the auxiliary bracing device,the deformation differential equations of the three kinds of space jib structure of the caterpillar crane are written and solved,and the buckling characteristic equation for the overall out-of-plane stability of different jib structures is obtained.The influence of the parameters of the super-lifting device and the auxiliary bracing device on the overall out-of-plane stability of various types of the large-flexibility space jib structures are studied,and the effect of each parameter on the overall structural stability were analyzed.The physical model and the equivalent model of a certain crawler crane are compared and analyzed,and the theoretical formula of this paper is used to verify the correctness of the conclusion.The research object of this paper covers the boom structure of the current boom-type luffing jib crane.From the perspective of analytical calculation,most of the crane boom systems including the main and sub-arm structures are included.The method of stability analysis of pitch luffing jib.Different from the angle of emphasis on the stability of individual components in the crane design specification,this study focuses on the overall stability or system stability of the composite structure that is not involved in the design rules.This work to some extent makes up for the difficulty of the overall stability analysis of the specific type of crane boom that is not taken care of by crane design specifications,and provides powerful help for the relevant crane design,production companies and departments,and also for crane-related specifications.Further revisions and improvements provide technical reserves.