Stability Analysis Of Crawler Crane Boom System Based On Simple Finite Element Model

With the development demand of construction, the crane is increasingly prone to large-sized, dominant-mountain and with lattice. With enormous use of high-strength steel material, the structure is strengthened, but the problems of structural stiffness and stability inevitablely occurs. So the stability analysis of complicated lattice structure becomes the crux of contemporary and large cranes' structure design and its calculation. Because of the lattice structure of the crane boom system and the angle between the boom and jib, it is very difficult to accurately calculate the overall stability with the traditional math-model and mechanics method.With the development of modern mechanics methods and computer technology, many practical commercial finite element analysis software were introduced to the crane design calculations. ANSYS as one of the best is used widely. However, at home and abroad, when applying of ANSYS, the establishment of finite model is usually in accordance with the actual structure of the boom system, so that it needs much workload under the condition of long boom or boom with various kinds of length.To solve the problems mentioned above, the author studies the boom structure, the simple finite element model, ANSYS linear buckling analysis and non-linear stability analysis, the active automation technology and the VB programming. The main research work and achievements are as follows:(1) Analyzing the working principle, structure characteristics and force condition of crawler cranes' truss boom, which makes we know the workload in modeling is very large and the model is not easy to revise, and so on. So, it's very necessary to simplify the boom finite element model.(2) Studying how to use the finite element analysis software ANSYS, including linear and nonlinear buckling analysis of the stability.(3) In accordance the overall boom structure, confirming the model simplifying method, selecting the variable cross-section beam element, calculating equivalent moment of inertia, improving the boom hinge point connection of all parts. To make sure this simplified method be accurate by comparing the result between truss model and simplified model. (4) Analyzing the actual characteristics of the force and the defects of linear buckling analysis, with the help of which it needs to calculate the stability with the method of nonlinear analysis, and then get the curve of load and deformation.(5) A special software of crawler crane boom system is developed, which encapsulates all the ANSYS operations, so that the users, being free from burdensome modeling, need only concentrate their attention on design variables. The software will automatically call for ANSYS analysis of the batch and save results.