Determination Of Failing Load For Lattice-Boom Of Crawler Cranes

Generally, the steps of finite element analysis is creating model, applying boundary conditions, and computing. Clearly, we can’t analysis without loading. It is hard to obtain the failing load directly for a structure. For example, when design crawler cranes, the loading capacity is unknown. A series of test load will be used for get the failing load, until the structures are broken. The crawler cranes are large structures, they consist of many elements, and they always perform large deformation due to slender structures. Geometrically nonlinear analysis is need. Due to a lot of working conditions they contain, the process is creating model and computing repeatedly when use commercial software to solve the problem. Clearly, it is not efficiently.This paper based on the characteristics of the crane, a new model based on twice degree of freedom reduction is presented and the failing load is got. Many substructures are divided for the crane, the internal degree of freedom can be reduced to the boundary, the boundary degree of freedom can be reduced to the section central points. Each substructure can be regard as a beam element, the computation speed is improved. When compute the stress, the equivalent nodal load can be regard as uniform load, the result is more accurate.The danger elements control the failing load, so we only focus on the danger elements and ignore other elements. Regard the bottom of crane as danger elements. The failing load is estimated based on the danger elements. Start at the estimate failing load to compute the accurate failing load.At last, A software is developed to search the failing load of crawler cranes by Matlab, this software is intelligent, efficiently, and generate report automatically. Numerical result shows this method is reasonable.