Needle punching of composites for preform assembly and thermomechanical enhancement

1. A method of forming a composite preform containing multiple laminates, the method comprising

providing a first sublaminate comprising stacked SiC fibers woven into a fabric;

providing a second sublaminate comprising stacked SiC fibers woven into a fabric;

joining the first sublaminate and the second sublaminate forming a component comprising a region of discontinuity sandwiched between the first sublaminate and the second sublaminate;

rigidizing the component;

softening the region between the first sublaminate and the second sublaminate; and

manipulating the region of discontinuity between the first sublaminate and the second sublaminate to reduce the incoherence between the sublaminates by moving SiC fibers from the sublaminates through at least part of the region.

2. The method of claim 1 , wherein manipulating the region of discontinuity is performed by needle punching, directed needle punching, ultrasonic, snares, directed water jets, barb punching, a comb, or some combination thereof.

3. The method of claim 1 , further comprising providing an insert in the region of discontinuity between the first sublaminate and the second sublaminate to at least partially fill the region between the first sublaminate and the second sublaminate.

4. The method of claim 3 , wherein the insert comprises a fiber, chopped fibers, a ceramic green body, a noodle, or some combination thereof.

5. The method of claim 4 , wherein the insert is manipulated by needle punching, directed needle punching, ultrasonic, snares, directed water jets, barb punching, a comb, or some combination thereof.

6. The method of claim 1 , wherein the rigidizing is performed with a thermal plastic, a water soluble polymer, a polyvinyl alcohol, or a combination thereof.

7. The method of claim 1 , wherein the softening is performed by applying heat to the needle, the region, or some combination thereof.

8. The method of claim 7 , wherein the softening is performed by applying solvent or water vapor to the polyvinyl alcohol.

9. The method of claim 7 , wherein softening comprises:

(a) applying resistively heated thermal tape to a backside of a needle punch head unit thereby heating needles of the needle punch head unit by conduction;

(b) induction heating the needle-punch head unit, which causes heating of the head unit by conduction;

(c) attaching lead wires to the needles in order to supply amperage from an external power supply;

(d) supplying water vapor or liquid through the needles; or

(f) heating the needles and the first and second preform parts by a method selected from the group consisting of ultrasonically exciting, microwave, laser, and oven.

10. The method of claim 7 , wherein the heating comprises induction, resistance, or radiation.

11. A method of fabricating a multiple laminate composite part, the method comprising:

fabricating a plurality of sublaminates;

forming the plurality of sublaminates into a laminate;

rigidizing the laminates using a thermoplastic or solvent soluble polymer;

assembling the plurality of laminates into the multiple laminate composite part; and

needle punching at least one laminate of the plurality of laminates of the multiple laminate composite part to remove discontinuities between the plurality of laminates of the multiple laminate composite part.

12. The method of claim 11 , wherein needle punching comprises needle punching by a plurality of barbed needles.

13. The method of claim 12 , wherein the barbed needles are made of steel and are coated with a ceramic coating selected from the group consisting of silicon carbide, silicon nitride, titanium nitride and diamond-like carbon.

14. The method of claim 11 wherein at least one laminate of the plurality of laminates includes a polymer binder to stabilize surrounding material to reduce distortion and act as a lubricant.

15. A method of fabricating a multiple laminate composite, the method comprising:

providing first and second sublaminates, wherein the first and second sublaminates are fabricated to a final thickness;

rigidizing the first and second sublaminates into individual shapes by infiltrating them with a thermoplastic or solvent soluble polymer,

assembling the first and second sublaminates into a final shape by applying heat in order to soften the thermoplastic or by introducing water vapor to soften a solvent soluble polymer, wherein at least one discontinuity is formed between the first and second sublaminates;

drying the first and second sublaminates;

applying pressure to the first and second sublaminates to ensure final dimensional conformity and reduce any gap between the first and second preform parts; and

needle punching the first and second sublaminates thereby removing the at least one discontinuity between the first and second sublaminates of the multiple laminate composite part wherein a plurality of needles are inserted traversing across a boundary between the first and second preform parts.

16. The method of claim 15 , further comprising providing an insert fabricated from plies of a fabric to fill a space between the first and second sublaminates.

17. The method of claim 15 , further comprising tooling the first and second preform parts in locations in which a head unit will not make contact.

18. The method of claim 17 , wherein tooling comprises applying an external clamping force in order to maintain dimensional conformance during needle punching.

19. The method of claim 15 , wherein needle punching comprises using a needle punching head unit set with a plurality of needles to create a desired surface area coverage to reinforce the first and second preform parts.