New iteration fractal branch and bound method for stacking sequence optimizations of multiple laminates

For laminated composite materials, the stacking sequence design is indispensable to make efficient use of the material properties. Laminated composites are usually fabricated from unidirectional plies of given thickness with limited fiber orientations to a small set of angles (e.g. 0°, +45°, 45°, and 90°). An improved version of fractal branch and bound method has been proposed to optimize multiple stacking sequences. The improved method, however, cannot be applied to complicated structures, since it is difficult to determine which is the most effective surface for designing such structures. In the present study, therefore, a new iteration fractal branch and bound method is proposed, which does not require empirical knowledge of the target structure. Here, this method is applied to a hat-stiffened panel to enable the stacking sequences of the two panel laminates and hat-type stiffener to be optimized simultaneously.