Research On Optimization Design Of Multi-boom Combination System Of Crawler Crane

Crawler crane is widely used in national construction for its advantageous performance in loading while moving. With the further requirements on lifting height and radius for large sport stadiums construction, a kind of multi-jib crawler cranes have been designed. The jib system of the cranes consists of at least three jibs (such as boom, luffing jib and fixed jib) and components which keep the geometrical relations of jibs (such as derricking bracket, stay bars, luffing ropes, mast etc). The geometrical parameters of these components which directly affect the capacity of crane are the important contents of overall design.Taking SDWF working condition composed of boom, luffing jib and fixed jib as research object, a new optimization idea and a new approach of building optimization objective were proposed, as well as an intelligent algorithm to solve the optimization problem, after doing in-depth studies of the working principle of whole crane, the mechanics model of the jib system, the geometry relations of components, the solution methods of multi-objective optimization, intelligent algorithm and MATLAB Programming techniques. The main research work and results of the paper are as follows:(1) Analyzing the composition and working principle of SDWF and the external loading conditions in the luffing plane, the mechanics model of the jib system considering the component weights was abstracted using balance principle. By changing the length values of derricking bracket and front stay bar in fixed jib system, the length values of two derricking brackets and two stay bars in luffing system, the length value of A-frame, stay bars and mast, the influence factors of component force trends were analyzed. As a result, the general design rules were carried out.(2) Referring to general design process of crawler crane, a hierarchical optimization idea was applied to optimize boom firstly then jibs. Combining with the force trends of component in different factors, a kind of economic indicator based on the cost was proposed as optimization objective functions of complex welded structures. Analyzing the characteristics of geometric model, the multi-objective optimization models of boom systems and jib system were established under the constraint principles of non-failure and non-interference.(3) After further studying the construction methods, a synthetical evaluation function of multi-objective optimization problem based on preference function was designed through inputting maximum forces of each component by the designer and defining preference ranges of optimization objectives with physical programming. Combined with the characteristics of genetic algorithm and particle swarm optimization, a multi-objective chaos genetic particle swarm optimization (MCGAPSO) based on Pareto dominance was designed to solve the problem. Finally, the optimization program for multi-boom system of the crawler crane was written in MATLAB-based platform.(4) Inputting boom parameters, optimization parameters, precision parameters, working parameters and algorithm parameters according to the optimization model of QUY750crawler crane, the advantages and disadvantages of the optimization algorithm in multi-jib crawler crane were analyzed respectively with the minimum force indicators and mixed economic indicators for the optimization goal, and then the reasonableness and effectiveness of the proposed modeling method were verified.