碩士 / 國立臺灣海洋大學 / 系統工程暨造船學系 / 105 / According to Structural Design Assessment rule from ship classification societies, more and more analyzing work are required to be done by the usage of the finite element method (FEM) program. In the rule, there are specific restrictions on mesh size and arrangement defined in order to obtain proper design parameters and stress level. In general, the orientation of the plate element mesh should follow the arrangement of the primary stiffener, so general element size used in the analysis is usually the distance between longitudinal stiffeners. Additionally, different class have different rules regarding mesh size under different loading scenario. It is difficult to discuss how the element size affects the accuracy of the ship structural analysis due to the geometric complexity. Therefore, the main object of this research is to develop a mesh generation program and then discuss the element size of ship design assessment in finite element method by convergence rate analysis.
In order to perform the mesh sensitivity test, we develop an interface program between ship structure database and FEM program, Abaqus. We first transform the information in the XML file from AM program and reconstruct the non-uniform rational basis spline (NURBS) function for each ship block. Then the program directly generates the initial graphics exchange specification file (IGES) and then the FEM mesh for the Abaqus. This program gives us flexibility to build FEM mesh with desired meshing orientation, element size and types, which greatly reduce the model building time and allow us to test the mesh sensitivity efficiently.
To accomplish the nonlinear mapping between real and parametric domain under NURBS framework, we developed a mapping algorithm based on the least square minimization method. The developed code can reconstruct the plate information through NURBS function completely with no error.
For the mesh sensitivity analysis and the accuracy estimation, we introduced the high order reconstruction of state and field variable and error indicator developed by Zienkiewicz and Zhu. Then we perform the mesh sensitivity analysis focusing on the stress field on various ship structural components. Very accurate error estimation can be found in standard benchmark examples, and this approach is proved applicable for general ship structural analysis and strength evaluation.
| Identifer | oai:union.ndltd.org:TW/105NTOU5345032 |
| Date | January 2017 |
| Creators | Chen, Yu-Fong, 陳玉豐 |
| Contributors | Guan, Pai-Chen, 關百宸 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 85 |
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