Nonlinear And Stable Analysis Of Big Flexibility Lattice Form Derrick Crane

Along with the technological advance and developments, the machine structure tended larger, more flexible and exacter. The linear analysis of the small displacement already hadn't satisfied the actual request of engineering before, the need of the calculation analysis method of high accuracy, high-efficiency large-displacement structure was more and more urgent in engineering application. This article used the geometry nonlinear problem of large-displacement beam and truss system with large engineering machine and metals structures in the on-linear flexible scope as a research object, and put forward to resolve the way of thinking and methods from theory analysis to program calculation.By means of analyse to the cantilever lattice structure such as crane body, a simple algorithm is introduced. Though the contrast of the algorithm used in cantilever lattice structure and cantilever solid web beam, we can get the algorithm that can be used to calculate the equivalent inertia moment of the lattice structure when it is regarded as solid web beam. In the foundation of the research to the stability variable cross-section beam, the bending defection differential equation of the variable cross-section beam in critical state of bucking is established. According to the edge condition of the structure, the differential equation is solved and bucking equation of variable cross-section beam is created. We can get the algorithm which can be used to calculate the equivalent inertia moment of the variable cross-section lattice structure when it is regarded as constant cross-section of solid web beam. The application of finite element method in the stability analysis is studied, and though the calculation of the lattice structure's critical force with finite element method. The initial moment method is improved. So we can analyse the stability of lattice structure as solid web beam without change it's geometry dimension.The text used the high precision FEM equation of beam and truss unit in the condition of small distortion from the side of the theory of II order, combined the way of large-displacements concomitant coordinate, and built up the basis method of nonlinear analysis of large displacement flexible beam and truss system. Because the beam unit equation in the condition of small-displacements was directly deduced by differential calculus equation through the theory of II order, and slid over the error brought by the theory of insect value. The large-displacements of frame came out through corresponding transform the relation between small distortion and concomitant coordinate method, there was no predigest and omit during the process, which guaranteed the accuracy of the exercise equilibrium of large-displacement unit.How to calculate the in plane and out of plane stability critical load of crane's jib with main and vice-arm structure, is explained. The specific method and process to calculate the overall stability is given by a concretely example.