Fabricating symmetric and asymmetric shapes with off-axis reinforcement from symmetric preforms
A device for obtaining off-axis reinforcement of a woven object. The device is made up of a fixed mandrel and a rotating mandrel. The rotating mandrel is connected to the fixed mandrel by a shaft that rotates through the middle of the fixed mandrel. The shaft allows the rotating mandrel to move up and down in relation to the fixed mandrel. A portion of the woven object can be clamped to the fixed mandrel while a second portion of the woven object can be clamped to the rotating mandrel. When rotated, the rotating mandrel causes the warp fibers in the woven object to twist off the 0° direction while fill or hoop fibers remain substantially parallel to the 90° direction.
1. A method of forming a multilayer woven object with off-axis reinforcement, the method comprising the steps of:
interweaving a first preform with warp fibers aligned substantially parallel with the 0° direction and fill fibers aligned substantially parallel with the 90° (hoop) direction;
interweaving one or more additional preforms with warp fibers aligned substantially parallel with the 0° direction and fill fibers aligned substantially parallel with the 90° (hoop) direction;
twisting said first preform in a first direction by restraining a first portion of said first preform in relation to a second portion of said first preform, wherein said twisting allows the warp fibers to twist off the 0° direction in a negative direction while the fill or hoop fibers remain substantially parallel to the 90° direction;
twisting said one or more additional preforms in a second direction by restraining a first portion of said one or more additional preforms in relation to a second portion of said one or more additional preforms, wherein said twisting allows the warp fibers to twist off the 0° direction in a positive direction while the fill or hoop fibers remain substantially parallel to the 90° direction; and
layering said one or more additional preforms with said first preform.
2. The method in claim 1 , wherein said multilayer woven object is interwoven using a Jacquard technique.
3. The method in claim 1 , wherein said multilayer woven object is seamless.
4. The method in claim 1 , wherein said first and one or more additional woven preforms are symmetric.
5. The method in claim 4 , wherein said first and one or more additional symmetric preforms are formed into an asymmetric preform.
6. The method of claim 1 , further comprising the step of placing one of said first and one or more additional preforms on a rotating fixture.
7. The method of claim 6 , wherein the rotating fixture comprises a fixed mandrel and a rotating mandrel.
8. The method of claim 7 , further comprising a step of restraining a first portion of said one of said first and one or more additional preforms on the fixed mandrel in relation to a second portion of said preform.
9. The method of claim 8 , wherein said twisting step is performed by rotating said rotating mandrel.
10. The method of claim 9 , wherein said twisting step causes said warp fibers to twist off the 0° direction to an angle related to the degree of rotation of said rotating mandrel.
11. The method of claim 9 , wherein said hoop or fill fibers remain substantially parallel to the 90° direction after said twisting step.
12. The method of claim 7 , wherein said fixed mandrel is symmetrically shaped.
13. The method claim of claim 7 , wherein said fixed mandrel is asymmetrically shaped.
14. The method claim of claim 8 , wherein said rotation is in the range of up to about 45°.
15. A multi-layered woven object comprising:
a first layer of a preform having a plurality of warp fibers, twisted off the 0° orientation in a negative direction and a plurality of fill or hoop fibers, aligned substantially parallel with the 90° (hoop) direction, wherein the plurality of warp fibers twisted off the 0° direction provide for off-axis reinforcement of the woven object; and
a further layer of one or more preforms having a plurality of warp fibers twisted off the 0° orientation in a positive direction and a plurality of fill or hoop fibers, aligned substantially parallel with the 90° (hoop) direction.
16. The multilayered woven object in claim 15 , formed using a Jacquard technique.
17. The multilayered woven object in claim 15 , wherein said object is seamless.
18. The woven object in claim 15 , wherein said object is symmetric.
19. The woven object in claim 15 , wherein said object is asymmetric.
20. The woven object in claim 15 , wherein said object is a preform for a radome.
21. The woven object in claim 15 , wherein said object is open ended.
22. The woven object in claim 15 , wherein said object is closed ended.
23. The woven object of claim 15 , wherein the fibers are impregnated with a polymeric resin.