Learn more on double-double !
Double-double – a new perspective in manufacture and design of composites
and the 2nd edition :
Simplifying the Design and Manufacture of Composite Laminates
Double-double (DD) is a new class of composite laminates, replacing the conventional quad that limits ply angles to 0, ±45, 90, and many other laminates called unconventional. In contrast, DD consists of two pairs of ply angles:
[±phi,±psi]
The goal is to have laminates that will be easier and faster to produce with lower weight , higher strength and so lower cost. Many manufacturing innovations can be achieved with DD and are not otherwise possible with the conventional quad laminates and unconventional laminates.
The first achievement was the use of one parameter for stiffness in trace, one parameter for failure criterion by leveraging Nettles circle, individual ply drops instead of symmetric pairs, one-axis layup with no cross-plying, and one continuous layup without stopping for mid-plane symmetry. The next step now introduced in the book is : one test for interlaminar stress, one laminate for design allowable generation, and one of two stacking sequences for DD to reach homogenization the fastest, and more simplifications to come.
All these steps that will make composites easier and lower cost to produce are enabled because of the homogenization of DD laminates. They are like orthotropic metals, but better than real metals because DD can have directional properties; DD can be tapered to save weight with which neither conventional and unconventional laminates, nor metals, can compete.
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THINK COMPOSITES is a nonprofit organization founded in 1983 by Professor Stephen W. Tsai and Dr Thierry Massard
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