Finite Element Analysis Of Nonlinear Stability Of Crane Lattice Boom

With the development of national economy and changes in construction methods,the lifting machinery is widely used in various fields.In order to meet the practical needs of the engineering,more and more slender crane booms are designed,making the boom may lose stability because of big deformation before strength failure,so its stability problem is increasingly serious.Besides,it is in general to be more sudden,and more hidden,so the stability of the lattice boom is a difficult and significant problem during the designing process.But because of the initial defect of the boom structure and the complexity of the force during the working process,its stability problem is a typical nonlinear extreme point instability problem.So the effect of the nonlinear should be considered when analysis its stability.Based on the predecessors' research results,the following work has been done.The research status of structural stability and the stability of the lattice boom are analyzed.Two methods of equivalent simplification: the conversion of slenderness ratio method and the equivalent moment of inertia method are studied,and the influencing factors on the slenderness ratio and the critical load of the boom are obtained.The theories of linear and nonlinear stability analysis are emphatically analyzed,and their similarities and differences are compared.The problems that need to be dealt with when calculating the geometric nonlinear stability of finite element using ANSYS and the whole calculation process are introduced.Based on the theory of arc-length method,the nonlinear stability of 280 t crawler crane lattice boom is studied.Through the stability of non-linear stability calculation,the whole process of load-displacement curves are obtained.By analyzing the curves,the selection principle of the critical load is discussed.The width,height,the outer diameter and wall thickness of the main chord of the boom are considered to change the conversion of the boom slenderness ratio,and the load-displacement curves with different slenderness ratios are obtained.By analyzing the curves,the critical loads are obtained.Besides,the influences of the width,height,the outer diameter and wall thickness of the main chord of the boom on the critical load,the flexibility of the boom and the instability process are discussed.These are useful in engineering design.