Research On Mesh Generation And Shape Optimization For Reticulated Shell In Free-form Surface

Reticulated shell structure in free-form surface is widely used in large public constructions not only due to its large span,reasonable framework and economic cost but also for its various smooth shapes.However,difficulties in mesh generation of reticulated shell have been caused by freeform surface.Meanwhile,shape of free-form surface will influence the mechanical behavior of reticulated shell significantly so it is meaningful to find methods to achieve a reasonable shape for reticulated shell in free-form surface.Based on Non Uniform Rational B-Spline(NURBS),researches on mesh generation and shape optimization for reticulated shell in free-form surface have been done and several results and conclusions are achieved.On the experience of mesh generation methods in traditional shell structures and mesh generation ideologies in finite element method,three mesh generation methods are proposed which are suitable for free-form surface.Mapping mesh generation for free-form surface is based on parametrical property of NURBS and FEM.Edge equal mesh generation for free-form surface is an expansion of traditional mesh generation methods in reticulated shell.In order to get equal members,equilateral mesh generation for quadrilateral grid is developed.Based on Height Adjusting Method,a shape optimization method for double-layer reticulated shell in free-form surface is developed.Minimum of strain energy of shell can be achieved while coordinates of joints are adjusted continuously with this method.This method is verified when mechanical property of structure improved and steel usage reduced after applying it to the practical project.All these methods are translated into programs with C++ and all information of models are stored in IGES standard which can be shared easily in most CAD softwares.