Boundary element method analysis of interface cracks between orthotropic layers

• Main Author: Poh, Kelvin Ah Song
• Other Authors: Ang Hock Eng
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Engineering::Mechanical engineering
• Online Access: https://hdl.handle.net/10356/166862
• Institution: Nanyang Technological University

To determine the stress intensity factor, phase angle together with the strain energy release rate of the crack-tip happening in double cantilever beam (DCB) and end-loaded-split (ELS) specimens, boundary element method consisting of quarter-point crack-tip element will be used. The material to be considered is one in which two layers of the same material, one orthotropic and the other transversely isotropic, are bonded to one another, with the latter layer being in the plane of transverse isotropy. The parameters, 1 and 2, which are imaginary roots of the characteristic equation, specifies the mechanical characteristics of orthotropic delamination specimens. To demonstrate the efficiency and reliability of the boundary element method software "BIE2DTD.exe" that will be utilised in this project and to evaluate the approach of modelling the crack problems using the program, various sample modelling will be shown. The findings demonstrate that as a/H goes to infinity, the normalised strain energy release rate and phase angle for both specimens stated will reach their asymptotic values. Additionally, it has been found that for a designated set of material parameters and the crack length to thickness ratio for both specimens stated, the aspect ratio of the beams has little or no detrimental effects on the figures of the normalised strain energy release rate and phase angle.