Research On Uniform Grid Meshing Methods For Fixed Free-form Grid Structure

Grid meshing takes an important part in the design of free-form grid structures and traditional manual meshing methods are generally cumbersome and time-consuming.Based on NURBS surface,several homogenization grid meshing methods are studied,the details are as follows:Firstly,followed with indicators for gird evaluation,the theoretical basis and related operations of NURBS surface are introduced.Then,based on the principle of minimum strain energy,the genetic algorithm is used to fine-tune the surface to improve its mechanical property.Besides,the principal stress trace diagram is drawn based on static analysis.Secondly,the surface development algorithm based on the principle of minimum area change is introduced as well as two methods for curve development.Planar mesh is generated by grid method and is adjusted and optimized by boundary cutting method,Laplacian smoothing or dynamic simulation method.In addition,the approximate distance method and the two-dimension parameter method are used to perform spatial mapping of the mesh.The two-dimension parameter method is less complex and low-error,but the application is restricted.What's more,the quality of the mesh and the mapping error are evaluated.The quality of the mesh is relatively high and the mapping error is directly related to the ratio of the radius of curvature of the surface to the target rod length.Thirdly,the guide line method is introduced.As for line translational propulsion method,after discretizing the guide line into points by established chord length,the planar mesh and surface grid is respectively generated by the restricted Delaunay triangulation method and the Voronoi diagram method.The mesh quality is quite normal.As for the equal-length meshing method based on bidirectional guide lines,two intersecting guide lines are required and the boundary adjustment is performed using boundary cutting method or dynamic simulation method.The rods of the quadrilateral mesh are all of the equal length and the triangular mesh can be obtained by orderly connecting diagonal lines of the quadrilateral grid cell.Finally,the grid meshing plug-in Unimesh is developed to better serve engineering design.