On stacking-sequence independent bending properties of Double-Double laminates—A short communication

Double-Double (DD) laminates are discussed as an alternative to conventional laminates used in aerospace practice, which are usually composed of 0°, 45°, 90°, and −45° plies. Double-Double laminates promise advantages mainly due to simplification of design, optimization, and manufacturing processes. Stacking-sequence independent bending properties of DD laminates allow for significant simplification in context of buckling analysis, as a recent publication shows. However, not all conceivable ply-orientation combinations in DD’s building block lead to it. The present short communication outlines briefly how stacking-sequence independent bending properties arise from DD’s laminate architecture. The analysis reveals two valid and also a single invalid angle selection, for DD’s balanced 4-ply building block.