Double-Double Composite Laminates for Versatile Manufacturing

Stanford researchers led by Stephen Tsai are advancing a new, much simplified design approach for composite laminates – termed "double-double" – that can replace conventional laminates for lighter, tougher, and lower cost airplane structures among other uses. Whereas legacy quad laminates have remained static since their development in the 1960s and are becoming so complex that have added time and cost in their use. They are no longer optimal. Double-double laminates simplify optimization, leading to new structures with unmatched low weight and cost. As a result, the double-double composite structures can be designed and produced with tapers to save weight, to have ply drops on the exterior surface to remove defects from the interior, and 1-axis layup of multi-axial tape and fabric —in a customizable manner—meet requirements of many applications, from heavily loaded aircraft wings to sports products.

Replacing legacy quad laminates with this technology opens up new frontiers. For example, it is possible to manufacture a fuselage, and wings in large pieces of structure, with fast layup, cured outside autoclave, with no fasteners, and easy to inspect and maintain. As other non-limiting examples, for rockets, pressure vessels, other structural forms including grid/skin as a special double-double, can also be designed and produced with ease, confidence and quality that can compete with metals

Related Technology

Stanford docket S19-225 - Manufacturing of Composite Grid/Core/Skin Structures
This invention describes a rib-stiffened, composite grid skin structure design, which is ultra-lightweight, stiff, strong, and easier and less expensive to manufacture.

Stage of Development

In addition to the progress summarized here, tools are available to help in the design of specific shapes while taking advantage of all the great features
of double-double composites. In additional to Otto, there are three ongoing programs with major aerospace companies having components designed and prototype produced and tested per double-double technology to be completed before summer 2021.