Patent ID: 8306789

Claim:
A method of designing a composite laminate, the laminate comprising a plurality of zones, each zone comprising a plurality of plies of composite material, each ply in each zone having a respective ply orientation angle, the method comprising the steps of: a. determining a global stacking sequence for the laminate, the global stacking sequence comprising a sequence of stacking sequence elements each stacking sequence element defining a respective global ply orientation angle, the percentages of the various ply orientations within the global stacking sequence defining a laminate constitution; b. determining a local laminate thickness for each zone; and c. determining a local stacking sequence for each zone by extracting a subsequence of stacking sequence elements from the global stacking sequence, wherein said steps a, b and c are carried out together in an optimisation process comprising: (1) assigning multiple sub-ply selection variables to each stacking sequence element, wherein each sub-ply selection variable represents at least one of the density and sub-ply thickness for a respective candidate ply orientation angle; (2) determining optimal values for the sub-ply selection variables and the local laminate thicknesses; and (3) assigning a single one of the sub-ply selection variables to each stacking sequence element thereby forcing a discrete choice of global ply orientation angle for each stacking sequence element, each of said method steps is implemented on a computer.