An Integrated Optimization Design Study Of Tower Crane Metal Structure Based On Revised Collaborative Optimization

At present, mechanic product becomes increasingly complex, and competitions among producers become more fury and rigorous, while the demands for products' performance from costume get much higher. So a product optimization design should not be limited within single part or component. Optimization design should starts from a much higher level, namely, from the view of the whole performance of a whole machine or an integrated system. However, facing such demanding, the traditional methods seem to be obsolete because of many inherent limitations. Under this situation, a new optimization design strategy, Multidisciplinary Design Optimization (MDO), emergedMultidisciplinary Design Optimization is a methodology for the design of complex engineering systems and subsystems that coherently exploits the synergism of mutually interacting phenomena. The MDO provides a method that can improve product quality using the synergism in the engineering systems and reduce development time through the concurrency of system design. The motivation for this research is the investigation of current MDO algorithms and application of the most promising MDO algorithm to the metal structure preliminary design of tower crane.Due to the interdisciplinary coupling inherent in the components subsystem of a complex system, two obstacles appear in MDO implementation, they are computational burden for system analysis, the complexity of communications among various subsystems. MDO algorithms address the two issues. Firstly the research presents a survey of basic MDO algorithm and the comparisons among them. And then points out that decomposition and coordination based bi-level algorithm will be the direction of future MDO algorithm.Collaborative Optimization (CO), originated from the Compatibility Constrained Optimizaiton (CCO), is a bi-level optimization algorithm based on system decomposition and coordination. In CO, when come to a certain subsystem optimization, the influences from other subsystems are ignored temporarily, while a set of local variables take their places in the subsystem design. As for the design conflicts among subsystems, coordination are performed through the solution of the system optimization. In application, the formally formulated CO encounters computational difficulties in most cases, namely in the system-level optimization, the Kuhn-Tucker condition can not be satisfied, in this research, a revised CO was presented, which de-constraints thesystem-level optimization through a set of proper weight factors while keep the subsystems' formulations unchanged. This new algorithm can sidestep the above mentioned computational difficulties and simplify the optimization problem.The emphasis of the current research is the study of the application of the revised CO in industrial case. In traditional optimization design of a tower crane, the components of a tower crane is singled out as design objects respectively and the inherent coupling links among the subsystems are ignored completely, which can't result in a optimization design in the system view of point. An integrated preliminary design of a tower crane metal structure, including head, jib and counter-jib, was carried out based on the revised CO, taking fully consideration of the inherent coupling mechanisms among the three components. In this way, system optimal design was reached. At the same time, an integrated design system, revised Collaborative Optimization Based Tower Crane design optimization system (COBTC), was developed based on the Matlab Graphic User Interface (GUI). A design case was presented to verify the design system and satisfying results reached.In the end, a summary of the whole research work was given out, together with the outlook on the applications of MDO to the complex mechanical system design...