The global buckling of a composite plate with a single rectangular delamination is studied using a smearing
method and employing exact stiffness analysis and the Wittrick–Williams algorithm. Computational
efficiency is achieved by avoiding discretisation into elements and non-linear analyses, making the
method suitable for parametric studies in preliminary aircraft design. Numerical results for longitudinal
compressive loading show the level of reduction in buckling load with increasing length and width of
delamination. Global buckling strength is increased as the delamination is moved towards the plate surface,
but is relatively insensitive to its widthwise and lengthwise location. The results are validated by
finite element analysis.