초록 ▼

An aerospace vehicle includes a plurality of composite stiffeners. Each stiffener of the plurality has a stack of plies of reinforcing fibers. At least some of the plies in the stack have reinforcing fibers oriented at ±α with respect to an axis of primary loading, where α is between 2 and 12 degree

An aerospace vehicle includes a plurality of composite stiffeners. Each stiffener of the plurality has a stack of plies of reinforcing fibers. At least some of the plies in the stack have reinforcing fibers oriented at ±α with respect to an axis of primary loading, where α is between 2 and 12 degrees. At least some of the plies in the stack have reinforcing fibers oriented at ±β with respect to the axis of primary loading, where β is between 50 and 85 degrees.

대표청구항 ▼

1. An aerospace vehicle comprising a plurality of composite stiffeners, each stiffener of the plurality having a stack of plies of reinforcing fibers; at least some of the plies in the stack having reinforcing fibers oriented at ±α with respect to an axis of primary loading, where α is between 2 and

1. An aerospace vehicle comprising a plurality of composite stiffeners, each stiffener of the plurality having a stack of plies of reinforcing fibers; at least some of the plies in the stack having reinforcing fibers oriented at ±α with respect to an axis of primary loading, where α is between 2 and 12 degrees; at least some of the plies having reinforcing fibers oriented at ±β with respect to the axis of primary loading, where β is between 50 and 85 degrees. 2. The vehicle of claim 1, further comprising a plurality of skin panels stiffened by the stiffeners, wherein the stiffeners include bases fastened to the skin panels by fasteners, whereby the fibers oriented at ±α suppress or delay ply splitting in the bases. 3. The vehicle of claim 1, wherein α is between 2 and 8 degrees. 4. The vehicle of claim 1, wherein α is between 3 and 5 degrees. 5. The vehicle of claim 1, wherein the reinforcing fibers oriented at ±α constitute at least 50% of the total number of fibers in each stiffener. 6. The vehicle of claim 1, wherein the stiffeners include webs, and wherein the fibers oriented at ±β are biased towards outer surfaces of the webs to increase stiffness in buckling and transverse bending. 7. The vehicle of claim 1, wherein the skin panels and the stiffeners include carbon fibers in a polymer matrix. 8. The vehicle of claim 1, wherein the vehicle includes a fuselage, wing assemblies and empennage; and wherein the plurality of stiffeners are included in at least one of the fuselage, the wing assemblies and the empennage. 9. The vehicle of claim 1, wherein all fibers in the stack consist of the fibers oriented at ±α and ±β; and wherein 20-30% of the total fibers are oriented at ±β to reach bearing strength levels similar to traditional 0/+45/−45/90 degree hard laminates. 10. An article comprising an aerospace vehicle stiffener, the stiffener including a base and a web, at least one of the base and web including a stack of plies of reinforcing fibers, at least 50% of the reinforcing fibers oriented at ±α with respect to an axis of primary loading, where α is between 2 and 12 degrees. 11. The article of claim 10, wherein the base has fastener apertures, whereby the reinforcing fibers in the base are oriented at ±α degrees to suppress or delay splitting caused by the fastener apertures. 12. The article of claim 10, wherein α is between 2 and 8 degrees. 13. The article of claim 10, wherein α is between 3 and 5 degrees. 14. The article of claim 10, wherein the reinforcing fibers oriented at ±α constitute 100% of the total number of fibers in the stack. 15. The article of claim 10, wherein the stack further includes plies of reinforcing fibers oriented at ±β degrees with respect to the axis of primary loading, where β is between 50 and 85 degrees. 16. The article of claim 15, wherein the fibers oriented at ±β are biased towards outer surfaces of the webs to increase stiffness in buckling and transverse bending. 17. The article of claim 10, wherein the reinforcing fibers in the stack include carbon fibers embedded in a polymer matrix. 18. An article comprising an aerospace vehicle stiffener, the stiffener including a base and a web, the web including plies of reinforcing fibers for providing strength in tension and compression along an axis of primary loading, the web also including plies of reinforcing fibers oriented at ±β degrees with respect to the axis of primary loading, where β is between 50 and 85 degrees, wherein the fibers oriented at ±β degrees are biased towards outer surfaces of the web to increase stiffness in buckling and transverse loading. 19. The article of claim 18, wherein the reinforcing fibers for providing strength in tension and compression are oriented at ±α with respect to the axis of primary loading, where α is between 2 and 12 degrees. 20. The article of claim 18, wherein the reinforcing fibers are carbon fibers embedded in a polymer matrix.