Requirements for lower emissions and operating costs make mass reduction of composite structures a significant issue for future aircraft. Here, minimisation of normalised elastic energy under an uncertain, general in-plane loading is used to indicate laminate efficiency and by equivalence minimum mass. Results are the first to investigate the comparative robustness of standard and non-standard angles to uncertain loading. They indicate that weight reductions of up to 8% can be achieved if optimum design, using standard angle (θ = 0°, ±45° or 90°) and industrial design rules, is replaced by optimising non-standard angles (0° ≤ θ ≤ 180°) directly for uncertain loading. However, greater reductions of up to 20% are possible through alignment of laminate balancing axes with principal loading axes. As such, a non-standard angle design strategy is only shown to be warranted if the demonstrated non-uniqueness of optimum designs can be exploited to improve other performance drivers.
Original languageEnglish
Pages (from-to)348-359
Number of pages12
JournalComposites Part A: Applied Science and Manufacturing
Early online date28 Sep 2018
Publication statusPublished - 1 Dec 2018



  • laminates
  • Strength
  • laminate mechanics
  • Robust Design

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