Computational Morphogenesis Of Freeform Structures Based On Hybrid Optimization Method

During the long history of the construction of the spatial structures, shell structures as a typical type play an important role. From the past to now, structural engineers build many representative shell structures. For the present demands of our human beings, the shell structures are built not only caring about the max span, but also for the architectural expressions and novel shape. And these demands become the one of most important development direction in spatial structures.For this purpose, the free-form surface has been introduced by architects, and then free-form structures are been carried out by structural engineers. For the shell structures, there are close relations between the shape and its structural behavior. Besides comparing with traditional shell structures, such as saddle surface, sphere and cylindrical surface, free-form shells have more complex and irregular shape. Therefore, finding the reasonable shape of the shell with excellent structural behavior is of crucial importance and becomes the most heatest problem in the recent researches. For the improvement of the efficience in the progress of structural morphogenesis in the free-form shelland creating more fruitful shell forms, the paper proposes a structural morphogenesis method based on the Hybird Optimization method. Considering those conditions above, some research works are carried out as fallows.(1) The establishment of the Hybrid Optimizaiton methodThe method combines the Gradient Optimization method and Pattern Search method together, and has two important steps. One is the calculation of the optimization direction and the other is optimization step length. The proximate negative gradient is taken as the optimization direction. In this way complex derivation can be avoided while the mathematical relation of the problem is considered. Finally the method is testified by some examples.(2) The establishment of the structural morphnogenesis method for the free-form structuresHybrid Optimization method is used to process the structural morphogenesis of free-form structures. During the progress, NURBS surface technique is taken to minimal the numbers of the control variables in the Hybrid Optimization method. It is an efficient way to improve the speed in structural morphogenesis. At last, several examples are made to verify the validity of this method.(3) Adjust the shape and thickness to generate the free-form structuresNURBS entity technique is introduced in this part to describe to form of the freeform structures. The form contains two part, shape and thickness. By controlling a small quantity of control points of the NURBS, the shape and thickness of free-form structures can be made. Then the form of the free-form structures can be generated based on the Hybrid Optimization method and NURBS entity technique. Finally, some examples are given to verity the right of the method.