Research And Implementation Of Quadrilateral Mesh Generation For Industrial CT Images

Computed Tomography(CT)can be used to show the internal and external structure of the workpiece without any damage,which plays an irreplaceable role in solving the difficult problems of reverse design and remanufacturing of the workpiece with complex internal cavity structure.The transformation of industrial CT images into finite element models can provide powerful technical support for the optimization design,quality evaluation,life prediction and remanufacturing process determination of the measured workpiece.Quadrilateral element is an important two-dimensional finite element,which is widely used in numerical analysis of structures,fluids and other fields.However,the quadrilateral mesh generated from industrial CT image data is mostly realized indirectly through CAD model,and there are few studies on using industrial CT image data to directly generate quadrilateral mesh.Based on the above problems,a method of generating quadrilateral mesh from industrial CT images is proposed in this paper,which combines the finite element technology and industrial CT technology,to realize the finite element analysis of products in a specific section or part.The main research contents are as follows:(1)A new mesh division method for CT image based on quadtree is proposed.Firstly,the interior region is divided into a grid with hanging nodes by using the characteristics of balanced quadtree.Then,the intersecting situation of suspension node chain in the internal grid is analyzed and processed.Finally,the template method is used to process the Hanging-node chains to eliminate the internal Hanging nodes.(2)To ensure the accuracy of boundary element,a method of generating boundary element accurately is proposed.Firstly,the accurate point position of the boundary node is completed by combining the minimized quadratic error function and Bezier curve.Then the boundary element is generated using the proposed node connection method.(3)To improve the quality of quadrilateral mesh,this paper combines geometric method and topological method to optimize the generated mesh.Firstly,the boundary element is optimized.Then,Geometric method is used to optimize the overall mesh.Finally,the quality evaluation indexes of quadrilateral element are used to evaluate the quality of the generated mesh.(4)The validity and correctness of the mesh generated in this paper are verified in ANSYS.The method presented in this paper has been applied to the reverse optimization design of castings with inner cavity.