QUASI-ISOTROPIC SANDWICH STRUCTURES

摘要

A quasi-isotropic sandwich structure is provided for resisting loads along multiple axes. The structure includes a core material sandwiched by fiberglass reinforcements. Fiberglass rovings are inserted through the structure such that the rovings are oriented along three axes, with adjacent axes separated by approximately 120°. Machines and methods for forming the structures are also disclosed. In one case, a machine having a single stitch head is reconfigured in each of three passes of the material to form the sandwich structure. In other cases, a machine having three stitch heads is used to form the structure with a single pass of the material. In some embodiments, the machine includes an indexing stitch head oriented at approximately 0° and two stationary stitch heads oriented at approximately−60° and +60° with respect to the machine direction. In other embodiments, the machine includes three stationary stitch heads oriented at approximately 90°,−30°, and +30°.