Buckling and first-ply failure of mechanically coupled composite structures

Lee, Ho Sum Jason (2023) Buckling and first-ply failure of mechanically coupled composite structures. PhD thesis, University of Glasgow.

Abstract

Double angle-ply or ‘Double-Double’ (DD) laminates offer new design possibilities in laminated composite materials design, permitting non-standard ply orientations with new layup configurations. DD laminates can be viewed as an alternative to so-called ‘Variable Angle Tow’ (VAT) laminates. The latter allow each ply within the laminate to possess constantly changing fibre directions and ply thicknesses. In contrast, double angle-ply technology uses straight fibres (with non-standard ply orientations and may confer similar benefits to VAT laminates, but without the added design complexity associated with a continuously changing fibre orientation and ply thicknesses, or indeed without the added manufacturing complexity and equipment costs involved in producing VAT laminates. This research focuses on the use of a lamination parameter design space as a way of designing laminated composite materials with both conventional and DD configurations.

Design spaces of compression and shear buckling of finite length Bend-Twist (B-T) coupled laminates manufactured from traditional ply orientations (containing 0°, 90° and ±45° ply orientations), with simply supported edges, are investigated. Both local and global optima of compression and shear buckling are shown in the lamination parameter design space, with practical design rules applied. Shear buckling contour maps demonstrate significant improvements in shear buckling performance with the presence of B-T coupling.

Buckling and First-Ply Failure (FPF) performances of DD laminates are discussed and compared to standard laminate configurations through stiffness matching. Polar plots have demonstrated that DD designs with coupled properties offer comparable FPF strength to standard laminates when off-axis orientation is applied to maximise anisotropy or Extensional-Shear (ES) coupling. It is demonstrated that DD laminates with B-T coupling can provide significant improvement in FPF strength over traditional laminates without reducing the buckling load.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Subjects: T Technology > TL Motor vehicles. Aeronautics. Astronautics
• Colleges/Schools: College of Science and Engineering > School of Engineering
• Supervisor's Name: Harrison, Dr. Philip and York, Professor Christopher
• Date of Award: 2023
• Depositing User: Theses Team
• Unique ID: glathesis:2023-83935
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 13 Nov 2023 16:06
• Last Modified: 13 Nov 2023 16:06
• Thesis DOI: 10.5525/gla.thesis.83935
• URI: https://theses.gla.ac.uk/id/eprint/83935