Research On Multi-scale Geometric Modeling Of Fibre Reinforced Composite Structures

Fiber reinforced composite, which has the characteristics of lightweight, high strength, devisable, etc, has been widely used in the field of areospace, ship, automobile, etc. With the rapid development of the demands, the problem of high cost which is caused by the material design process has gradually become the focus of attention and restrict its development. Aiming at this problem, the paper mainly researched the geometric modeling of fibre reinforced composite structures by analysing the composite laminate.The paper proposed a integrated structure and material fiber reinforced composite product geometric modeling system which is based on the Top Down Approach. It divided the design process into three section-- conceptual design, geometric design and engineering design. And applied the results of the study to the software system according to actual needs.Based on the parameter feature molding, this paper researched the conceptual design and modeling method of the fiber reinforced composite product. Accroding to the product structural features and the prepreg material properties, it modelling the featurebased product geometric lattices. On that basis, the paper modelling the material propertybased fiber bundle microstructure. And get the results of integrated feature lattice and material model product conceptual model. This model reflects the digitization of design infomations and has accomplished the coupling of structural information and material information, which mainly embody the multi-scale of fiber reinforced composite product design process.Based on that conceptual model, the paper researched the geometric modeling of fiber reinforced composite product. It modelling the product structural geometric model based on features lattice by using the NURBS curved surface. Aimming at the product characteristic of multi-scale, it build the polylaminate product division material geometric model which is based on the partition and fitting of NURBS curved surface, and modelling the transition surface of ladder layer border area. Geometric design will finally obtain the integrated structure and material model which is based on the surface unit. This model inherit the information of conceptual design, and present the multi-scale product structure and material information.Based on that geometric model, this paper researched the engineering modeling of fiber reinforced composite product by using the structured mesh. Aimming to the finite element mesh, it design a density controllable structured mesh modeling algorithm which is based on the isoline of NURBS curved surface. Aimming to the defect of composite laminate, it respective modelling the randomized and probability-based single defect distribution model, and build the bubble defect microcosmic cell model by using the random ellipsoid model, which mapping the defect distribution model. Engineering design will finally obtain the structured mesh model which has been defined the defect infomations. This model match with the finite element mesh, and has accompolished the multi-scale definition of macro grid and micro-meso defect.Based on the research of this paper, a fiber reinforced composite product geometric modeling software system has been compiled. It accomplished the prototype system which is based on the Open Inventor shader cores. It achieved the progressive working process of conceptual design, geometric design and engineering design, and integrated the design of structure and material from macro to meso and then to micro-scale. Finally, it verify its feasibility by giving the example of wing cover and ‘J’ shape fillet.