High-Performance Composites is read by qualified composites industry professionals in the fields of continuous carbon fiber and other high-performance composites as well as the associated end-markets of aerospace, military, and automotive.
Issue link: https://hpc.epubxp.com/i/101340
focus on design Bi-angle faBrics find first Bicycle manufacturer sees dramatic productivity gains using unbalanced F or decades the composites industry has emulated the homogeneous properties of metals, designing quasi-isotropic structural laminates with stacked unidirectional tapes ��� ���black aluminum.��� The classic 0��/90��/+45��/-45�� layup has predominated not only because resulting laminates exhibit similar stiffness in all directions, but also because it minimizes bending/twist coupling and gives metal- centric engineers more con���dence. But this symmetrical and, until recently, sacrosanct con���guration, could be giving way to a unique alternative. ���I had this idea for a very long time that there was a way to relax these design rules and achieve optimized results with asymmetrical layups,��� recalls the alternative���s inventor, Dr. Stephen Tsai, professor emeritus at Stanford University (Palo Alto, Calif.). In fact, Each C-PLY bi-angle layer features 0�� and +45�� plies, stitched together 0�� spread tow Tsai and the late Edward M. Wu ���rst addressed the issue in 1971, when they introduced the Tsai-Wu Failure Criterion (see ���Learn More��� p. 48). In the paper���s introduction, they contended that a more reasonable approach was to stack alternating unbalanced (anisotropic) layers (e.g., 0�� and a shallow angle). Forty years later, this ���bi-angle��� concept (pat. pend.) has found its ���rst commercial application in a new pro- AMERICAN ARTISAN BICYCLES��� CARBON EX ROAD BIKE FRAME -45�� spread tow (orientation achieved by ���ipping every other bi-angle layer to create [0��/+45��/-45��/0��] +45�� spread tow C-PLY SCHEMATIC (158 g/m2 aerial weight) Head tube (wall thickness: 0.145 inch/ 3.6 mm) Connection lug formed by overlapping tube joint with C-PLY and aramid plies Down tube (wall thickness: 0.083 inch/2.0 mm) Seat stays Chain stays Fork Seat tube (wall thickness: 0.094 inch/2.4 mm) Design Results ��� Unbalanced,shallow-anglelaminates ofnew,verythinbiaxialfabricsreplaces ���blackaluminum���andsimplimeslayup. 46 | high-performance composites ��� ���Potato-chipwarping���ispreventedby stacking16ormorelayersofthethin unbalancedlayers. ��� Smallbicyclemrmhasachievedaero- spacequality,withaten-folddecrease inlaborcosts,outoftheautoclave.