抄録
Design, manufacturing and testing can be simplified with trace for stiffness, and enclosed area of failure envelopes for strength. They represent respectively the total capacity for stiffness and strength. When the traditional quad laminates of 0, ±45, 90 are replaced by double-double in [±phi/±psi] many rules that have governed laminate selection for over 60 years become much simpler and more rational. In particular, double-double is field-based and has only 4 plies as the basic building block. Homogenization, easily achieved with 4 or more repeated blocks, offers faster and simpler layup with tapering to reduce weight and cost, that cannot be done with quad. Structure so built will not warp, and have no interior defects because all ply drops are located on the exterior surface. A new Lam search tool that selects the best laminate for various structures can not only rate but also scale materials and laminates without recalculation. Design allowable needs only to be based on uniaxial tension and compression data in X and X’ and confirmed by as-built double-double. Next generation research should cover validation of anticipated strength of double-double laminates in static, fatigue, vibration, and impact loading, with effects from combinations of temperature and moisture. Homogenization has eliminated the stacking sequence and blending problems, and made laminates as easy to design as orthotropic metals. It is better than metals because tapering is easy as part of additive manufacturing.
