ABSTRACT
The existence of several intersection curves and intersection points makes the solid mesh generation procedure for a partially overlapped CHS K-joint not a trivial task. To reduce the complexity of the model/ mesh generation procedure, the mesh is first created in the form of a surface mesh, which is then converted
into a solid mesh using an extrusion algorithm (Xu 2006). Weld details and crack profiles can be added in subsequent steps. This method of mesh generation is flexible in such a way that at different modeling stages, meshes with different levels of details can be generated and employed for special applications. For example, a surface mesh without any welding details (SURF_0 W) could be extracted out for quick assessment of the fatigue strength of the joint while a surface mesh with welding details (SURF_1 W) could be formed with little addition effort for quick SCF estimation. For a more intensive and detailed study on the distribution of hot spot stress (HSS) around the joint intersection, full solid meshes (SOLID_1 W and SOLID_0 W) with or without welding details could be used. Eventually, in the case that a full numerical study for a crack joint is needed, a full solid mesh with welding and crack details ( (SOLID_CR) can be generated. In these meshes, different kinds of element are used depending on the targeted purpose. For example, the entire mesh SURF_0 W is represented by second order triangular and quadrilateral shell elements, while mesh SURF_1 W is a mixed mesh consists of both shell elements and solid prisms and tetrahedrons for the welds and joint details. Second order brick elements, prisms, tetrahedrons and pyramid elements are used in the meshes SOLID_0 W and SOLID_1 W. In addition, the quarter point crack elements are used in the mesh SOLID_CR around the crack front for accurate SIF prediction. A flow chart for the mesh generation scheme is presented in Figure 1.
