A New Class of Hygrothermally Stable Laminates with Extension-Twist Coupling

In prior work, classes of hygrothermally stable elastically tailored laminates that retain extension-twist coupling have been analytically determined. In the present work, six-, eight-, and ten-ply laminates that maximize extension-twist coupling have been constructed, confirmed to be hygrothermally stable, and tested to demonstrate their optimized behavior. The laminates were manufactured from T300/976 graphite/epoxy and tested in a biaxial tension-torsion machine. The amount of extensiontwist coupling was shown to be dependent on the applied axial force. An optimized benchmark family was also manufactured and tested for comparison. All optimized laminates have higher extension-twist coupling compared to the benchmark family with the six-ply laminate having the best coupling. An analysis of the robustness of coupling to errors in ply angle is also included.