Compressive strength stabilizing manufacturing method of anisogrid composite structure ribs without an outer skin

This paper describes a manufacturing method for the ribs of a cylindrical anisogrid composite structure without an outer skin. This research presents two direct compression techniques for the ribs during wet filament winding with T700 continuous carbon-fiber tows. In addition, the strength of the helical rib manufactured using the proposed compression process was compared to that of the manufactured rib that did not use the compression process. The average compressive strength of the helical rib manufactured using the proposed methods is 394 Mpa and 247 MPa according to the failure mode, respectively. Although the ribs manufactured using the pro-posed method did not show increase in strength, decreases in the standard deviation for both compressive failure modes (66% and 21% of the structure made without the proposed compression method) and was observed. Thus, the proposed compression techniques resulted in compression strength stabilizing thanks to decreasing void content. Furthermore, structural stiffness was indirectly evaluated and it was found that the improvement was over 150%.