Stacking sequence constraints in non-conventional composite laminate optimisation

A method to take design guidelines into account during the optimisation of non-conventional laminates is developed. Non-conventional laminates are defined as laminates with angles other than 0◦, ±45◦or 90◦. The optimisation is performed using the method of successive approximations. Some design guidelines are interpreted as a limit on angle or angle difference, and are implemented as such. The 10% rule is interpreted as a limit on the ratio of the stiffness in any two directions. It is posed in the optimisation as a positive-semi-definite matrix constraint. Other design guidelines are implemented as user-defined options, for example having a ±45◦layer on the outside. Initial results of a square plate under bi-axial tension show that the constraints are always satisfied, while achieving good performance.