Optimization Of Box - Type Main Girder Of Bridge Crane Based On Chaos Theory

As the main part of crane, metal structure being the main influence factor of design technology, security and economic indexes and life for lifting machinery, its design quality directly affect the crane in all aspects of technical indicators. At this stage, the allowable stress method based on experience analogy is applied to the hoisting machinery metal structure design and calculation. The method is not only tedious in the design and calculation with the stronger intensity of labor and longer cycles but also only used to the analysis comparison in a few candidate schemes which cannot be very accurate to evaluate their advantages and disadvantages. So, the optimal design scheme is usually hard to be obtained. With the development and application of computer technology, the optimal solution being automatically selected in the design process, a rapid and effective method that is the optimization design can be set up. By combining the optimization theory with computer technology, this design method is the effective tool to solve the problem of complex design. The method can greatly improve the design quality and efficiency. It has obvious economic benefits and social benefits. Therefore, crane metal structure which is lighter and meets the design requirements can be confirmed by introducing the optimal design method to the crane metal structure design, through compiling crane metal structure optimization program with the operation ability of computer to complete the best match of metal structure design parameters to avoid material waste, improve the economic performance and reduce the production cost.When the optimization mathematical model is constructed, the optimized design variable must be conducted to round processing because of the previous crane structure being as mix variables of the optimization, which lead to the design variables beyond the feasible region so that the optimization is failure. In this paper, the structure size in actual production often take mm integer times and single rolling plate "1". The specified thickness of steel plate is repositioned. The optimization design of the crane metal structure belongs to the constraints the nonlinear discrete variable optimization problems. Chaotic Particle Swarm Optimization(CPSO) algorithm is introduced into the optimal design of the crane metal structure, introducing chaos mechanism respectively in population initialization and the local search of the global optimal solution. Optimization examples show that the CPSO algorithm is simple, fast, and avoiding the precocity and stagnation phenomenon in evolution, so as to improve the global convergence rate of the optimal solution. At the same time, Double Chaos Optimization algorithm is put forward(DCOM), using the randomicity, ergodicity and regularity of Chaos to make the optimization calculation respectively based on three mapping methods such as Logistic, Tent and Cube. The calculation results show that, under the premise of the quality of optimal solution, the method can effectively shorten the calculation time, reduce the computing cost and improve the design efficiency. Using the parametric design language APDL of the finite element analysis software ANSYS to conduct the static analysis and modal analysis of crane structure to extract the strength, stiffness and vibration frequency value of the checking point for the machine, the consistency of calculation results shows the correctness of the parameterized finite element model, which lay a foundation and provides a scientific basis for the further study of crane metal structure. Finally, based on VC++ software platform to complete the integration of the optimization design and parametric finite element analysis, the optimization design software of bridge crane metal structure is obtained.