Nonlinear Research And Analysis Of Booms For Crawler Crane

With the rapid development of the national economy,the scale of infrastructure facilitiesis expanding,the weight,height and volume of related equipment are also increasing,so that crawler cranes are used more and more widely in engineering lifting because of there advantages.The lattice truss boom,as the main force component of crawler crane,determines the lifting performance of crane.The problem of stiffness deficiency is obvious due to the increase of flexibility of boom with the increase of the length of the boom and the use of high-strength steel and the improvement of the manufacturing process,which can cause large initial deflection under self loading,and the structure tends to “soften” and lose stability when subjected to axial and lateral loads.Therefore,the influence of geometric nonlinear caused by the second-order effect on structural stress and deformation can not be neglected.So it's very necessary to establish the equilibrium equation for the nonlinear analysis of structures in the position after the deformation.The conventional analysis method is to establish a complex finite element model of the boom in finite element analysis.However,the specific structural parameters are uncertain in the initial stage of crane design,it's necessary for check analysis to repeatedly modify the structural parameters to carry out "trial calculation" check.The finite element method takes a lot of time because of the complexity of modeling and the problem of non-linear non-convergence problems.In order to improve design efficiency and design accuracy,a fast and relatively accurate nonlinear analysis of boom is needed.In response to above problems,the geometric nonlinear analysis of the slewing plane and the boom hoisting plane is analyzed from the second-order effect angle based on the analysis and summary of the previous research results,the main research works are as follows:Firstly,based on the principle of equal critical load,the method of inertia moment equivalent method is deduced to simplify the lattice boom.Then the formula for calculating the moment of inertia in the rotary plane and the amplitude plane of the boom is obtained,By cases,the method's ration is verified.Secondly,the analytic method of the nonlinear problem is derived based on the second-order effect.The differential equation of the compression member with box cross section is established in the position after the deformation.It's decomposed into the superposition of sinusoidal and polynomial curves,which are both under axial pressure.Because of including the form of undetermined geometric parameters,the deformation equation is obtained by analyzing the boundary condition and equilibrium condition.So,based on the boundary conditions and the equilibrium conditions,the traditional solution tothe problem of the deformation of bending members can be transformed from the pure mathematics problem of solving the integral constant of complex differential equations to the problem of determining the geometric parameters of flexural curves which makes the physical meaning be explicit and the concept is clear.Thirdly,nonlinear analysis of actual boom model in slewing plane and the hosting plane is carried out by using the derived analytical method of nonlinear problems of compression members.Then the deformation of the boom is solved and compared with the result of the geometric nonlinear calculation of the finite element software ANSYS,which verifies the rationality of the method.Finally,from the perspective of the influence of the boom structure parameters on the boom deformation,the influences of the working angle,width and height of the boom cross section,and the thickness of the auxiliary member and the chord member on the deformation are analyzed.These can provide a certain reference for the design of boom products.