Crack induced fracture problems in engineering structures

• Main Author: Koh, Stanley Wei Wen.
• Other Authors: Xiao Zhongmin
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Mechanical engineering::Mechanics and dynamics
• Online Access: http://hdl.handle.net/10356/16776
• Institution: Nanyang Technological University

The project focuses on the investigation of the interactions between a crack and two phases of materials in a curved body. This area of research is of great importance in engineering structures such as pipelines, which requires welding. Stress intensity factors are evaluated for a finite crack in a primary medium with the presence of a secondary material. Stress intensity factors are employed to determine whether there is crack growth under certain loading configurations and configurations. The Finite Element Analysis software, ANSYS, is being utilized in the analysis processes. The methodology used in obtaining the stress intensity factors at the crack tip is a 2-Dimensional plane-stress finite element method. The parameters being analyzed include the degree of curvature of the plate, the thickness of the plate, the difference in elastic modulus between the two materials, the relative length of the crack to the primary plate, and the relative length of the primary material to the secondary material. The results are examined and are presented in tables as well as in graphical formats, showing the normalized intensity factors against the respective parameters. The introduction of a secondary material significantly lowers the stress intensity factor and may be engaged in deterring crack propagations. However to achieve this, the secondary material has to be introduced with suitable combinations of elastic modulus, and appropriate geometrical configurations of both primary and secondary materials.