Multi Scale Integrated Topology Optimization Design Of Composite Structures

Topology optimization is one of the most effective methods in structural design. With topology optimization method, the macroscopic structure and the microscopic materials can be optimized simultaneously, eliminating the boundaries of structure and material in order to further tap the potential of materials. With the development of the multi-scale method, integrated design of the structure and material from the perspective of macro and micro scale, has been becoming an important research field of topology optimization.In this thesis, the multi scale integrated design method of composite materials is studied based on the unidirectional fiber reinforced composite. Firstly, optimal topology design of microscopic material is studied, with an energy-based homogenization method adopted, and the main optimization parameters are discussed, based on which, several interpolation models and enhancement methods are compared. The center line-based enhancement and the topology-based enhancement method are studied. Compared with the theoretical value, the effectiveness of the methods are verified by numerical examples.For structural stiffness maximization of macroscopic scale, optimization model is established. Stepwise design strategy is studied by introducing the idea of scale separation. The multi-scale design of material and structure based on single kind of microstructure is realized by the examples of cantilever beam and simply supported beam. The multi scale topology optimization design of the composite is completed by using the method of center line based enhancement, which verifies the effectiveness of the method in this thesis.Finally, the relationship between the macro and micro scale is considered, focusing on the multi-scale integration design method of composite structures. FE2 scheme is introduced to bridge the two scales. BESO topology optimization method is used for the concurrent design, based on which the overall implementation process is established. The multi-scale integration design of composite materials structure is realized by the examples of flat structure and clamp structure by using the method of topology based enhancement, which verifies the effectiveness of the method in this thesis.In this thesis, the scale-associated multi-scale integrated optimization design of composite structures is completed, which is of great significance to the development of multi scale integrated design and the solution of practical engineering problems.