Tow-steering of composites using Automated Fiber Placement (AFP) providessignificant flexibility for the composite designer to spatially tailor fiber orientationwithin a given ply. However, tow-steering is not without drawbacks which maynegatively impact the strength and stiffness of the material. In general, there are twosources of strength reduction of concern: inherent geometric complexities due to towconvergence zones (e.g., gaps and overlaps) and manufacturing defects related to thein-plane curvature of the tows.The purpose of the present work is to identify the mechanical properties of towsteeredlaminates relative to those of an unsteered laminate for the application of a 39-foot passive-aeroelastically tailored wingbox. The tow-steered laminate currentlystudied employs a fixed ply fraction wherein all tows are steered together and maintainfixed relative angles to each other, thus minimizing the number of unique effectivelayup sequences. An alternate approach wherein half the plies (the equivalent quasiisotropiccomponent) are unsteered is also considered.The design and fabrication of tow-steered and unsteered panels for mechanicalcoupon testing is described. Normalized test results for modulus and strength arepresented for tow-steered laminates, relative to equivalent unsteered laminates.
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