Buckling optimisation of composite panels via lay-up tables

The strategy to optimise a composite panel is based on a multi-level optimisation. The fust level defmes a thichess law for the skin (thichesses and angle percentages for each uniform area all over the panel) and stiffener properties (height, thichess...). The objective function is the total weight of the panel. The optimisation takes into account strength criteria (in-plane behavior) and stability criteria (out-of-plane behavior). At this level, composite material behavior is modelled as a homogeneous material and effects of lay-up are not taken into account for buckling calculations.

So in a second level, a lay-up table is used to define the lay-up associated with each integer thichess of the skin and to insure lay-up continuity between different thichesses Optimisation of this table towards buckling is the topic of this paper.