No abstract

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof be al form. Please note that during the production process fore it is published in its fin errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

No abstract

No abstract

Balanced laminates, with zero in-plane to out-of-plane stiffness coupling are optimised over a range of tri-axial (Nx, Ny and Nxy) critical design loadings for minimum normalised elastic energy; equivalent to optimising for minimum mass in the absence of matrix failure. Laminates comprising standard angle plies (0, ±45 and 90) are designed for either a fixed design loading with a 10% minimum ply percentage rule (current practice) or directly for an uncertain design loading. Results show that the 10% rule performs well for the majority of design loadings. Nevertheless, for 8% of design loads considered, significantly lower mass (>10%) designs are achieved with standard angle plies when designing directly for uncertain loading. Expansion of the ply envelope to include designs with continuous angles (0° ≤ θ ≤ 180°) under an uncertain loading allows maximum mass savings up to 16% over current design practice. However, when designing directly for an uncertain loading, no significant mass reductions are achieved through the use of continuous angles.