CA2547978A1

CA2547978A1 - 3-d fabrics and fabric preforms for composites having integrated systems, devices, and/or networks

Info

Publication number: CA2547978A1
Application number: CA 2547978
Authority: CA
Inventors: Alexander Bogdanovich; Don Wigent
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-11-19
Filing date: 2004-11-18
Publication date: 2005-06-02
Also published as: US20050146076A1; US7926519B1; US7611997B2; WO2005050409A2; WO2005050409A3; US20060057920A1; WO2005050409A8

Abstract

A 3-D fabric preform (10) for composites including a three-dimensional engineered fiber preform formed by intersecting yam system components (4, 6, 8); and at least one system, device, and/or network integrated with the preform for providing a predetermined function, wherein the at least one system, device, and/or network is introduced prior to formation of a composite structure including the preform, thereby providing a 3-D fabric preform (10) for composites. Also, a method for forming the 3-D fabric preform for composites including a three-dimensional engineered fiber preform (10) formed by intersecting yam system components (4 6 8); and at least one system, device, and/or network integrated with the preform for providing a predetermined function, wherein the at least one system, device, and/or network is introduced prior to formation of a composite structure including the preform, thereby providing a 3-D fabric preform (10) for composites.

Description

1 3-D FABRICS AND FABRIC PREFORMS FOR COMPOSITES HAVING.

2 INTEGRATED SYSTEMS, DEVICES, AND/OR NETWORKS

3 Background of the Invention 4 ~1) Field of the Invention The present invention relates generally to fabric materials and, more particularly, 6 to fabric preforms used for composites further including sensors, devices, and/or 7 networks.
8 (2~ Descri tion of the Prior Art 9 Composites are materials formed from a plurality of components combined to ~ form an integral structure. Typically, fabrics referred to as preforms are used within a 11 composite structure provide a supporting framework for the composite, with a resinous 12 material added thereto for filling interstitial regions and for providing a more amorphous 13 component for transforming an otherwise non-stiff fabric preform into a rigid component 14 ' for further shaping, machining, or other processing. The name "fiberglass" is a common slang term for one such composite material, but many other composite materials employ 16 fabrics as preforms, including metal matrix, and carbon or ceramic matrix composites.
17 Prior art composites are known to employ sensors, devices, and/or networks for 18 the purpose of sensing fatigue, failure, changing conditions, and the like and are generally 19 refered to as "Smart Structures", or "Smart Materials"; however, in all cases known at the time of the present invention, any such sensors, devices, and/or networks were added or 21 incorporated into the composite at or after the formation of the composite itself, i.e., they 22 have not been included in the fabric preform prior to composite formation in any case.
23 Further, such sensors, devices, and/or networks were added or incorporated into three-1 dimensional fabrics.
2 "Smart Structures" instrumented with a variety of sensing and/or actuation 3 systems and devices have been one of the major focuses of science and engineering in the 4 last two decades. They continue attracting great interest, which is primarily motivated by the fast growing capabilities of modern microelectronics and new structural materials 6 which, in combination, enable development of the miniature, fully integrated in the 7 structural material, multifunctional in-situ diagnostic and real-time control means.
8 Typically, a smart structure, which is commonly associated with a vehiclular, civil, 9 marine, or other critical structural .member, contains multiple attached or embedded sensor and/or actuator elements and some hardware and software for collecting, 11 analyzing and storing information regarding the strain, temperature, damage, cracks, 12 delamination, and other parameters characterizing structural integrity of the airframe. For 13 ' smart structures to be relied on for mission or flight critical decision, the above flight 14 critical characteristics must be continuously monitored, and structural integrity should be assessed in real time. Accomplishing this very complex task requires, in the first place, to 16 reliably integrate and interrogate a large number of individual sensors distributed over the 17 structure, as well as the means to receive data from them.
18 Various three-dimensional fabrics are often used as reinforcement of composite 19 materials and as such are referred to as preforms. These fabrics may utilize both flexible and rigid elements ranging from staple cotton yarn to solid ceramic wires or rods, and 21 may be usefully employed in both their fabric states, or further processed as within 22 composites, and as such no major distinction is made here between the terms "fabric" and 23 "preform", whether extremely flexible as with a fine insulation fabric or rigid as with a I ~ structural wire grid formed with rigid rods. The plurality of controllably isolated or joined 2 fiber or tow layers formed in 3-D fabrics provide particularly valuable opportunities, well 3 beyond that of 2-D fabrics, for the development of elaborate functional systems, circuits, 4 or networks as is so often done with mufti-layer integrated circuits or mufti-layer hydraulic manifolds. The very regular, inherently periodic nature of 3-D
orthogonally 6 woven and other 3-D fabrics, which are mentioned here as examples, allows them to 7 perform functions similar to those of 3-D grids, arrays or networks.
Examples of such 8 ~ functions include phased array emissionrdetection, shielding or refraction or diffraction 9 of a known wavelength, damage and delamination detection, resin flow and cure rate control, acoustic emission signal sensing, active control of shapes, vibration suppression, 11 supply or transmission of fluids to mention a few.
12 Optical fibers and sensing devices associated with them are one desirable means 13 for producing smart structures. Optical fibers are available in small diameter; they are 14 flexible, relatively light, relatively strong, relatively inert to environmental degradations, are not affected by electromagnetic influence, carry no electrical current.
They can be 16 quite easily adhered to surfaces of materials like metals, ceramics, plastics, composites, 17 or embedded within thereof. When applied to composite structures in the past, optical 18 fibers 'have been commonly bonded to the exterior or embedded between layers of 19 prepreg without adversely affecting structural integrity. The optical fiber can be embedded in any curable, rrioldable, or laminated composite material without 21 significantly disrupting the regular manufacturing process. While embedded into the 22 structure, optical fibers neither significantly affect the mechanical characteristics of the 23 composite nor concentrate mass at a particular location along the structure. Advantages 1 of conventional fiber optic strain sensors over conventional electromagnetic strain gauges 2 include simplicity, low cost, insensitivity to electromagnetic interference, immunity to 3 electrical potential differences, operability over wide temperature ranges and operating 4 environments, end use of simple and low-cost electronics. Besides, the use of fiber optics to replace conventional electric wires reduces the intensity of propagating 6 electromagnetic waves, which results in reduced detectability of the system/device and 7 interference with on-board computers.
8 A large variety of fiber optic sensors have been developed and are currently in 9 use. Those include displacement, strain, temperature, pressure, moisture, wear, acoustic, , magnetic, rate of rotation, acceleration, electric, electric current, trace vapor sensors to 11 mention a few. The sensors may be adapted to modulate the Light in different ways so as 12 to encode multiple signals. For example, different characteristics of interest may be 13 encoded by intensity, by frequency, or by phase. The two major types of fiber optic 14 sensors are either phase modulated or intensity modulated sensor devices.
Phase modulated fiber optic sensors may be characterised by their required use of coherent tight 16 sources, single-mode fibers and the need of relatively complex optical and electronic 17 circuitry. This type sensor applications depend primarily upon force field induced length 18 changes and strain induced refractive index changes, which are the cause of phase 19 shifting as the Light travels through the sensing length of the optical fiber; this can be detected using an interferometer apparatus. The intensity modulated type fiber optic 21 sensors, on the other hand, depend primarily on an optical source of constant intensity, 22 which is ordinarily acted upon by an external force field.

1 Numerous fiber optic sensors known from the prior art can be categorized in 2 many different ways. One of them - segregating sensors into extrinsic and intrinsic, is of 3 particular interest in the context of present invention. Two sensor types belonging to 4 either of these groups, namely Extrinsic Fabry-Perot Interferometric (EFPI) sensors and Bragg Grating (BG) sensors are used here for the reduction to practice demonstration. It 6 is well established that EFPI sensors have much lower thermal sensitivity, also sensitivity 7 to lateral strains, to dynamic perturbations (mechanical vibration, acoustic waves), and to 8 magnetic fields than BG sensors. It is also believed that EFPI sensors are better suited for 9 the use in hostile environments, which can be faced, specifically, when the sensor is exposed to the full manufacturing cycle of a composite material. On the other hand, an 11 EFPI sensor (which is a complex device itself), after it is integrated in the composite 12 material, has much higher potential to become a considerable local origin of disturbance 13 than a BG sensor (due to the latter one is mechanically indistinguishable from its carrying 14 optical fiber). Also to the advantage of BG sensors - a large series of them can be carried by a single optical fiber; it is much easier to embed/integrate BG sensors in the composite 16 and simultaneously interrogate them under loading.
17 Present invention is related to engineered three-dimensional fabrics and fabric 18' preforms for composite materials instrumented with fiber optic sensors and other types of 19 sensing, actuating and information transmitting systems, devices and networks which can be suitably integrated in the said fabrics and fabric preforms. The said fabrics and fabric 21 preforms are treated as the carriers of the said systems, devices and networks. From this 22 viewpoint, the said fabric preforms, after being processed into composite materials and 1 structures, become integral with them, together with their carned said systems, devices 2 and networks.
3 In order to clearly identify the novelty of the present invention and its distinct 4 place among prior art in the field, the following overview of the prior art in the field of composite materials and structures and textile fabrics with embedded/integrated fiber 6 optic sensors is provided, including comments on their respective methods of their 7 fabrication.

8 U.S. Patent 4,221,962 teaches how an optical glass fiber is embedded in a composite 9 laminate to monitor and detect the presence of moisture in the interior of the panel.
According to the invention, the optical fiber is "sandwiched" between the plies during ply 11 lay-up, becomes an integral part of the laminate, and as such goes through the laminate 12 curing cycle. ' 13 U.S. Patent 4,537,469 describes a reinforced structural member, which is composed from 14 a plurality of high tensile strength optical fibers, arranged into at least two parallel layers and embedded in the resin material. Importantly, all described optical fiber architectures 16 in the invented composite are limited to two-dimensional woven architectures.
17 U.S. Patent 4,581,527 describes a system consisting of a plurality of layers of optical 18 fiber grids for detecting damage and assessing its location in laminated composite 19 materials. The optical fiber grid system is implanted in a composite laminate during~its fabrication and becomes integral with it. Each optical fiber grid includes two orthogonal 21 series of optical fibers.
22 U.S. Patent 4,603,252 also describes a plurality of light conducting fibers, which is 23 included in laminated composite material. The light transmitting fibers are included, as at 1 least one separate layer, in between adjacent structural laminas, importantly, in some 2 regular pattern.
3 U.S. Patent 4,772,092 describes method of measurement and detection of cracks and 4 fissures in test objects (specifically, laminated composites), particularly under utilization of light conducting fibers, which will break in the instance of a crack or fissure. In the 6 preferred embodiment of this invention, it is described that several light conducting fibers 7 are either inserted within the layers of regular fibers by replacing some of the regular 8 fibers, or.light conducting fibers are placed in between adjacent layers of regular fibers in 9 a mesh. After that the respective' layers are put together and impregnated in. resin. The detailed description of the invention and illustrative material do not indicate that any type 11 of fiber architecture other than a unidirectional fiber placement or generic 2-D woven 12 architecture, has been intended in the invention.
13 U.S. Patent 4,836,030 describes the method of embedding a plurality of optical fibers in 14 the composite material in pre-determined two-dimensional configuration (a serpentine pattern, specifically). Detection of light passing through any given optical fiber indicates 16 that the composite is free of damage in the area along the extent of that optical fiber;
17 however, integrating optical fibers within a fabric structure that is a 2-D
woven structure 18 ,or the like, where fiber paths are typically non-orthogonal and not substantially straight 19 due to necessary crimping, prevents the integration of these fibers within the fabric itself.
A layer of film adhesive is formed, in which optical fibers are embedded. The film 21 adhesive Dyers are incorporated in composite laminate at the time of its manufacture.
22 Optical fibers, embedded by this approach between different plies of a laminate, provide 23 information about damage formation through the thickness. Two examples of practical NOT FURNISHED UPON FILING

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1 Figure 16 shows Flexible SystemlDevice Materials Joining Base Material after Initial Fabric 2 Formation Process by Addition 3 Figure 17 shows Rigid System/Device Materials Joining Base Material after Initial Fabric 4 Formation Process by Addition Figure 18 shows Flexible System/Device Materials Joining Base Material after Initial Fabric 6 Formation Process by Substitution 7 Figure 19 shows Flexible System/Device Materials Joining Base Material after Initial Fabric 8 Formation Process by Addition 9 Figure 20 shows System/Device Materials Integrated during Preforming Emerge in Dangling Fashion from Composite According to Design 11 Figure 21 shows SystemJDevice Materials Integrated during Preforming Meet Surface of 12 Composite for Access According to Design 13 ' Figure 22 shows Example of 3-D Braided Fabric/Preform with Integrated System/Device 14 Materials Figure 23 shows a 3-D Braided T-Stiffener Preform Showing Integration of System/Device 16 Materials Along both Axial and Braiding Pathways.
17 Figure 24 shows a 3-,D Multi-Axial Woven Fabric/Preform with System/Device Materials 18 Integrated into Warp, Fill and Bias Pathways 19 Figure 25 shows a 3-D Multi-Axial Warp-Knitted or Stitch-Bonded Fabric/Preform with System/Device Materials Integrated into Warp, Fill and Bias Pathways 21 Figure 26 shows an Illustration of Addition or Substitution of System/Device Materials into 22 Fabric/Preform During Regular Fabric Formation 1 Figure 27 shows an Illustration of Addition or Substitution of System/Device Materials into 2 Fabric/Preform After Regular Fabric Formation 3 Figure 28 is a digital photograph of Optical fiber included in fiber supply for additive integration 4 into 3-D weaving.
S Figure 29 is a digital photograph of Laser light going into network material in standard supply 6 "creel" and into loom.
7 Figure 30 is a digital photograph of Rigid EFPI is miniature and was integrated automatically in 8 3-D weaving.
9 Figure 31 is a digital photograph of Optical fiber emerging from 3-D woven preform.
Figure 32 is a digital photograph of 32 Preform being processed into composite by VARTM
11 method.
12 Figure 33 is a digital photograph of Carbon fiber composite beam test specimens with rigid 13 integrated sensors along straight paths.
14 Figure 34 is a digital photograph of Fabric with integrated 11 optical fibers in 3 axes.
Figure 35 is a digital photograph of Braided preform with integrated optical fibers in axial 16 looped circuit (2 round trips).
17 Figure 36 is a digital photograph of Composite produced with preform having optical sensing 18 fiber pulled in additively after fabric formation; it contains hundreds of sensors.
19 Figure 37 is a digital photograph of Heat from fingers touching sensing fiber.
Figure 38 is a digital photograph of Fibers and signal emerge from completed fabric showing 21 signal still coming from supply.
22 Detailed Description of the Preferred Embodiments 23 In the following description, like reference characters designate like or 1 corresponding parts throughout the several views. Also in the following description, it is 2 to be understood that such terms as "forward," "rearward," "front," "back,"
"right,"
3 "left," "upwardly," "downwardly," and the like are words of convenience and are not to 4 be construed as limiting terms.
Referring now to the drawings in general, the illustrations are for the purpose of 6 describing a preferred embodiment of the invention and are not intended to limit the 7 invention thereto. As best seen in Figure 1, a 3-D fabric preform for composites is 8 provided, generally referenced 10, for providing a three-dimensional engineered fiber 9 preform formed by intersecting yarn system components 4, 6, and 8, respectively; and at least one system; device, and/or network from a supply 12, 14 integrated with the 11 preform for providing a predetermined function, wherein the at least one system, device, 12 and/or network is introduced prior to formation of a composite structure including the 13 preform, as illustrated in this figure, thereby providing a 3-D fabric preform for 14 composites. The supply may include a flexible network or device 12 and/or a rigid network or device 14.
16 In one preferred embodiment of the present invention, as shown in Figure 1, a 17 fabric preform being formed on a fabric forming machine includes, as part of the fabric 18 forming process, the addition and integration of at least one system, device, and/or 19 network along with the fiber systems used to form the fabric structure;
this may be done automatically, semi-automatically, or manually, depending upon the specific system, 21 device andlor network being used.
22 In another preferred embodiment of the present invention, as shown in Figure 2, a 23 fabric preform 18 that has already been formed on a fabric forming machine is now 1 having the addition and integration of at least one system, device, and/or network 26, 20, 2 22, within the fiber systems used to form the fabric structure; this may be done 3 automatically, semi-automatically, or manually, depending upon the specific system, 4 device and/or network being used. Figure 2 further illustrates the addition of a device/network materials) by insertion, stitching, or as with "embroidery" 16, as well as 6 the addition of rigid device/network materials by insertion, displacement, or pull-through 7 along straight paths 20, and the addition of flexible device/network materials by insertion, 8 displacement, or pull-through along straight paths 22.
9 Figure 3 shows an example of a special shaped fabric or preform with integrated network, device, and/or sensors. In particular, flexible network/device/sensor materials 11 are shown following a convoluted path 24 and rigid , flexible network/device/sensor 12 materials are shown following a straight path.
13 ' Figure 4 illustrates by a schematic view the addition of network, device, and/or 14 sensor materials to a textile system supply 28, which proceed through any textile processing system 30 according to the present invention as set forth herein, to provide a 16 textile fabric or preform 32 having integrated network, device, and/or sensor materials 17 therewith. as part of the integral, unitary construction of the 3-D fabric or preform.
18 Figure 5 illustrates by a schematic view the addition or substitution 42 of network, 19 device, and/or sensor materials 44 into a textile fabric or preform, wherein the fabric or preform axe first formed from a textile system supply 34 having standard materials only 21 l in the supply, i.e., not including any network, device, and/or sensor materials, the 22 standard supply proceeding through any textile processing system 36 according to the 23 present invention as set forth herein, to provide a textile fabric or preform having 1 integrated network, device, and/or sensor materials therewith as part of the integral, 2 unitary construction of the 3-D fabric or preform 46.
3 The preform according to the present invention may be formed by various fabric-4 forming processes, resulting in 3-D woven fabric, 3-D braided fabric, and/or multiaxial fabric structures. Where a 3-D braided fabric is used, preferably the systems, 6 devices, and/or .networks are provided in the axial direction of the structure. ' In some 7 specific systems, such as conductive components or sensors may be used in other 8 directions within 'the structure. For a typical 3-D braided fabric formed on an automated 9 machine,, 64 carriers with holes or tubes for axial fibers are preferably used to integrate the systems, devices and/or netowrks via the tubes into the braided fabric in an automated 11 manner. Semi-automated and manual introduction may be used as well or as an 12 alternative. In the case of a 3-D multiaxial fabric, typically stitch-bonded or multi-axial 13 warp-knitted fabrics (stitched through the thickness) or insertion fabrics (generally not 14 composites applications) may be used.
Figure 6 is a perspective illustration showing the addition of relatively smaller 16 rigid system/device materials to certain elements within a Multi-Axial Warp Knit, Stitch 17 Bonded, ~or other insertion fabric/perform such as that manufactured by the Liba, Mayer, 18 or other similar 3-D fabric formation processes. The un-crimped in-plane pathways allow 19 for the integration of both rigid and flexible system/device materials.
Knitting/Stitching which alternate from top to bottom, binding the assembly, follow a more complex path, 21 allow for the integration of only the most flexible system/device materials, while rigid 22 system/device materials may merely be inserted between the base yarns in the through 23 thickness direction as if a needle through fabric. As seen in Figure 6, rigid or flexible 1 system, device, network, and/or sensor materials 38 are added to the base materials; also, 2 knitting or stitching yams 40 are shown, along with in-plane 0°, 90°, +45°, -45° yarns 42 3 in the base fabric structure.
4 Figure 7 is a perspective illustration showing the substitution of relatively equal sized rigid system/device materials for certain elements within a Multi-Axial Warp Knit, 6 Stitch Bonded, or other insertion fabriclperform such as that manufactured by the Liba, 7 Mayer, or other similar 3-D fabric formation processes. The un-crimped in-plane 8 pathways allow for the integration of both rigid and flexible system/device materials.
9 Knitting/Stitching which alternate from top to bottom, binding the assembly, follow a more complex path, allow for the integration of only the most flexible system/device 11 materials while rigid system/device materials may merely be inserted between the base 12 yarns in the through thickness direction as if a needle through fabric. As seen in Figure 7, 13 rigid or flexible system, device, network, and/or sensor materials 46 are being substituted 14 for the 'base materials; also, knitting or stitching yarns 44 are shown, along with in-plane 0°, 90°, +45°, -45° yarns 48 in the base fabric structure.
16 Figure 8 is a perspective illustration showing the addition of relatively smaller 17 system/device materials to certain elements within a Multi-Axial 3-D woven 18 fabric/perform. The un-crimped in-plane pathways allow for the integration of both rigid 19 and flexible systemldevice materials. Z-yarns, which alternate from top to bottom of 3-D
Multi-Axial weave, connecting the assembly, follow a more complex path, which allows 21 only for the integration of continuous flexible system/device materials or discrete rigid 22 system/device materials. As seen in Figure 8, rigid or flexible system, device, network, 1 and/or sensor materials 50 are being added to the base materials; also, z-yarns 52 are 2 shown, along with in-plane 0°, 90°, +45°, -45°
yarns 54 in the base fabric structure.
3 Figure 9 is a perspective illustration showing the substitution of relatively equal 4 - sized rigid system/device materials for certain elements within a Multi-Axial 3-D woven fabric/perform. The un-crimped ire-plane pathways allow for the integration of both rigid 6 and flexible system/device materials. Z-yarns, which alternate from top to bottom of 3-D
7 Multi-Axial weave, connecting the assembly, follow a more complex path, which allows 8 for the integration of continuous flexible systemldevice materials or discrete rigid 9 systemldevice materials. Figure 9 shows isolated system, device, network, and/or sensor materials 56 in the filling or bias direction, isolating base materials 58, and common 11 systemldevice materials 60 forming a simple circuit from the isolated system, device, 12 network, and/or sensor materials in the filling or bias direction.
13 Figure 10 is perspective illustration of how the system/device materials in Filling 14 ~ or Bias directions are included in simple circuit formed by planned intersections with system/device materials in special Z-yarn. This is exemplary of how the sequence of 16 interlacement of various elements within the fabric may be controlled or manipulated in 17 three dimensions so as to allow periodic access to a system/device, or to form planned 18 intersections with in-plane elements and thus circuits as desired. As seen in Figure 10, 19 rigid or flexible system, device, network, andlor sensor materials 62 are being substituted for the base materials; also, z-yarns 64 are shown, along with in-plane 0°, 90°, +45°, -45°
21 yarns 66 in the base fabric structure.
22 Figure 11 is an edgewise illustration of how the system/device materials in Filling 23 or Bias direction are included in simple circuit formed by planned intersections with 1 system/device materials in special Z yarn and the sequence of interlacement may be 2 controlled or manipulated so as to allow periodic access to a system/device, or to form 3 planned intersections with in-plane elements and thus circuits as desired.
Figure 11 4 shows Z/Axial 74 having an altered path making intended intersection with other system/device materials, a circuit path A-A 76, along with in-plane 0°, 90°, +45°, -45°
6 yarns 72, 70, 68, respectively, in the base fabric structure.
7 Figure 12 shows Flexible System/Device Materials Joining Base Material in Fabric Formation 8 Process by Addition.
9 Figure 13 hows Flexible System/Device Materials Joining Base Material in Fabric Formation Process by Substitution.
11 Figure 14 shows Rigid System/Device Materials Joining Base Material in Fabric Formation 12 Process by Addition 13 Figure 15 shows Rigid System/Device Materials Joining Base Material in Fabric Formation 14 Process by Substitution Figure 16 shows Flexible System/Device Materials Joining Base Material after Initial Fabric 16 Formation Process by Addition 17 Figure 17 shows Rigid System/Device Materials Joining Base Material after Initial Fabric 18 Formation Process by Addition 19 Figure 18 shows Flexible System/Device Materials Joining Base Material after Initial Fabric Formation Process by Substitution 21 Figure 19 shows Flexible System/Device Materials Joining Base Material after Initial Fabric 22 Formation Process by Addition 1 Figure 20 shows System/Device Materials Integrated during Preforming Emerge in Dangling 2 Fashion from Composite According to Design 3 Figure 21 shows System/Device Materials Integrated during Preforming Meet Surface of 4 Composite for Access According to Design Figure 22 shows Example of 3-D Braided Fabric/Preform with Integrated System/Device 6 Materials 7 Figure 23 shows a 3-D Braided T-Stiffener Preform Showing Integration of System/Device 8 Materials Along both Axial and Braiding Pathways.
9 Figure 24 shows a 3-D Multi-Axial Woven Fabric/Preform with System/Device Materials Integrated into Warp, Fill and Bias Pathways 11 Figure 25 shows a 3-D Multi-Axial Warp-Knitted or Stitch-Bonded Fabric/Preform with 12 System/Device Materials Integrated into Warp, Fill and Bias Pathways 13 Figure 26 shows an Illustration of Addition or Substitution of System/Device Materials into 14 Fabric/Preform During Regular Fabric Formation Figure 27 shows an Illustration of Addition or Substitution of System/Device Materials into 16 Fabric/Preform After Regular Fabric Formation 17 Figure 28 is a digital photograph of Optical fiber included in fiber supply for additive integration 18 into 3-D weaving.
19 Figure 29 is a digital photograph of Laser light going into network material in standard supply "creel" and into loom.
21 Figure 30 is a digital photograph of Rigid EFPI is miniature and was integrated automatically in 22 3-D weaving.
23 Figure 31 is a digital photograph of Optical fiber emerging from 3-D woven preform.

1 Figure 32 is a' digital photograph of 32 Preform being processed into composite by VARTM
2 method.
3 Figure 33 is a digital photograph of Carbon fiber composite beam test specimens with rigid 4 integrated sensors along straight paths.
Figure 34 is a digital photograph of Fabric with integrated 11 optical fibers in 3 axes.
6 Figure 35 is a digital photograph of Braided preform with integrated optical fibers in axial 7 looped circuit (2 round trips).
8 Figure 36 is a digital photograph of Composite produced with preform having optical sensing 9 fiber pulled in additively after fabric formation; it contains hundreds of sensors.
Figure 37 is a digital photograph of Heat from fingers touching sensing fiber.
11 Figure 38 is a digital photograph of Fibers and signal emerge from completed fabric showing 12 signal still coming from supply.
13 Manufacturing methods for, and resultant fiber/tow paths . within various 3-D
14 fabrics or preforms may be manipulated and exploited so as to allow a relatively easy integration of special, actively or passively functional, flexural or rigid materials within 16 them, by adding said materials to one or more of the host fibers/tows or, alternatively, by 17 replacing one or more fibersltows with the said material. In this way, a fabric is created, 18 which includes various systems, devices, networks, etc. Such 3-D fabrics and preforms 19 containing integrated systems/devices/networks are the principal object of this invention.
Some immediate examples are 3-D fabrics and preforms with integrated optical 21 fibers/fiber bundles and sensors integrated within them, which is one particular object of 22 this invention; actuation means such as piezoelectric fibers, fiber bundles, ribbons, and 23 other suitable elongated bodies for shape control, vibration and dynamic instability 1 suppression, which is another particular object of this invention;
electrical conductors like 2 metal wires, filaments, strands made of stainless steel, copper, carbon, or electrically 3 conductive polymers, which is another particular object of this invention.
Besides, fast 4 progress in the area of microelectronics and nanomaterials makes it feasible to associate complex microelectronic devices, systems and networks to textile fibers/tows and then 6 integrate them into 3-D fabrics and preforms, which is yet another particular object of 7 this invention.
8 Making use of complex fiber architecture in 3-D weaves, braids or knits provides 9 endless opportunities for creating large arrays or networks of sensors, actuators, circuits, conduits and other systems and devices that may serve such purposes as transmitting 11 light, providing controllable light displays for signals or screens or camouflage, 12 conducting electricity and heat, performing logical functions, providing data and power 13 infrastructure in structures, serving as antennae or emitters for sound or electrical power 14 radiation, shielding electromagnetic waves, diffusing radiation or signals, inducing movement or shape change, de-icing, just to mention a few.
16 The system/device materials of interest may be integrated into 3-D
fabric/preform 17 during its formation on the respective machine or mechanism during the regular textile 18 process, which is another object of this invention. Alternatively, they can be integrated 19 after the fabric/preform has been produced, which is yet another object of this invention.
Flexible system/device materials may be introduced along any pathway followed by the 21 regular fiber/tow forming the fabric, specifically, in three, four or five directions, which 22 are most typical cases for the 3-D fabrics of our primary interest. It is very important to 23 ensure that going along such pathways does not impart severe damage to the 1 system/device material, or does not substantially hurt the functional ability of that 2 system/device. The ability and freedom of the 3-D preforms to provide straight pathways 3 suitable for many device materials, while at the same time providing efficient structural 4 performance is an advantage of the present invention over the inclusion of similar device materials in 2D fabrics which are limited in this respect.
6 Integration may take place in several fashions, including simply substituting the 7 system/device material for the flber/tow host material in desired locations during fabric 8 formation, addition of the system/device material to the host materials during formation, 9 replacement/substitution of the host materials after formation, and addition of the system/device materials to the host materials after formation. The described methods of 11 integrating relatively flexible systems/devices into 3-D fabrics and preforms is another 12 object of this invention. Straight (or nearly straight) pathways used in 3-D textile 13 manufacturing processes (the immediate examples are warp fiber direction in 14 orthogonal weaving, multiaxial 3-D weaving or mufti-axial knitting/stitch bonding, and longitudinal fiber direction in 3-D braiding) allow even relatively rigid materials to be 16 used, along with the regular fibers/tows without distortion or functional impingement to 17 the integrated system/device material. This statement has been thoroughly verified 18 through experimentation with both rigid and flexible optical devices and fibers, ceramic 19 fiber, and stainless steel wire bundles on~the available automated 3-D
weaving and 3-D
braiding machines. The described methods of integrating relatively rigid systemsldevices 21 into 3-D fabrics and preforms.is another object of this invention.
22 Prior to formation of the fabric with integrated system/device material such as 23 optical fiber, or metallic conductor, or piezoelectric/magneto-strictive actuator/sensor, or 1 shape memory alloy element, may be wound together with the host fiber/tow in the 2 desired ratio onto the standard spools or beams, thus forming a hybrid tow, which is 3 loaded into the 3-D weaving, braiding or knitting machine so as to be included in the 4 fabric formation process. Alternatively, the system/device material may be used as substitute for some number of regular fibers/tows by adding it to the supply of a textile 6 machine as if weaving a simple plaid, ribbed, or hybrid fabric. Where the effects of the 7 additional volume, mass, or other physical property of the system/device material causes 8 no undesirable effects, the system/device material may be simply added to the existing 9 host materials .by methods including but not limited to fastening the system/device material to a host material and allowing it to be pulled into the akeady formed fabric as a 11 parasite, or by allowing the system/device material to be inserted by the rapiers, needles, 12 or fluid jets along with the resident host material. Standard "color picker"s and jacquard 13 heddle controls used fore plaids and upholstery fabrics allow for on-demand placement of 14 system/device material in looms, and the grippers,on standard rapiers can accommodate rigid materials. The described methods of incorporating a system/device material into the 16 tow/yarn supply system is another particular object of this invention.
17 The fundamental concept of integrating various systems/devices into 3-D
fabrics 18 and fabric preforms described above enables the next step, namely to manufacture 19 polymer matrix, ceramic matrix, metal matrix, carbon-carbon or carbon-silicon composite materials and structures instrumented with such systems/devices. This concept, which is 21 the second principal object of this invention, extends to any composite material, which .
22 can be made with the use of the aforementioned instrumented fabric preforms. A.ny 23 suitable fabrication technique can be utilized for this purpose. In the case of polymer 1 matrix composites one can use methods like Resin Transfer Molding, Vacuum Assisted 2 Resin Transfer Molding, Resin Film Infusion, Pultrusion, Hot Press Forming, Autoclave 3 Curing, etc: Of course, special care has to be taken to protect the integrated system/device 4 against elevated cure temperatures/pressures or against elevated temperatures/pressures required for thermal forming of a composite structural part. The integrated system/device 6 should not contain any structural elements, adhesives, coatings or other (typically 7 polymeric) components that would not withstand the projected composite processing 8 and/or in-service temperatures/pressures.
9 The above requirement becomes much more severe in the case of ceramic matrix, metal matrix and carbon-carbon composites, which must be processed at high 11 temperatures, and likely exposed to high temperatures in seivice. The selection of 12 appropriate systems/devices that can be safely integrated into these types of composites 13 without special thermal protection means asks for special attention and care. For 14 example, even if pure glass fibers and pure ceramic fibers can withstand high temperatures used for processing some of the aforementioned composites, conventional 16 fiber optic sensors or piezoceramic actuators based, respectively, on glass or ceramic 17 materials, may include various polymeric elements (claddings, substrate films, insulating 18 casings, etc.), which will not withstand the high processing or in-service temperatures. To 19 substantiate this point, we make a reference to U.S. Patent 5,338,928, where it was suggested that "an optical fiber capable of high temperature environments can be inserted 21 into the structure prior to chemical vapor infiltration as in the case of CMCs or prior to 22 plasma spraying, foil-fiber-foil construction, or other assembly methods as in the case of 23 MMCs". However, according to that patent, each optical fiber was clad with an inert 1 cladding, such as gold or iridium. Also, gold-coated silica fibers or sapphire fibers were 2 suggested as the preferred types of fibers for integration into high-temperature 3 composites.
4 Piezoelectric sensors/actuators commonly used for embedment into graphite fiber composite laminates require a suitable insulating casing, which can be, for example, a 6 polyimide film Kapton, as suggested in U.S. Patent 5,195,046 or a fiberglass fabric/epoxy 7 composite, as recommended in U.S. Patent 5,305,507. Of course, other suitable approaches can be explored. One possible solution, which is another object of this 9 invention, is inspired by the nature of 3-D fabrics. Its essence is to functionally hybridize the fabric, i.e., substitute glass fiber or other insulating material fiber tows for some of 11 graphite fiber tows in those parts of the fabric where piezoelectric sensors/actuators have 12 to be integrated. This approach enables to naturally surround the piezoelectric element 13 with sufficient amount of insulating material fibers and thus ensure its insulation from 14 graphite fibers contained in the other neighboring tows.
Electrical conductors, like metallic wires/fibers/strands or polymeric conducting 16 fibers/yarns, represent another category of systemsldevices that can be integrated into 3-17 D fabrics, preforms and composites, though they require special treatment before being 1 ~ used in the integration process. Depending on the functional purpose, different pre-19 integration treatments of this kind systems/devices can be applied. They may be intentionally left bare and allowed for mutual contacts at the crossover points, thus 21 providing a conductive circuit. They may be left bare, but in a non-interlacing pattern (as 22 dictated, for example, by the application considered in U.S. Patent 5,210,499). They can 23 be locally insulated by polymeric fibers/tapes or may be separated at the crossover points 1 by special electrically partially resistive material (like in the case of the pressure sensor 2 construction in U.S. Patent 4,795,998). Some of these requirements can be naturally 3 fulfilled by using another object of this invention, which is to purposefully choose those 4 layers of warp, weft, and/or bias fibers/tows and specific locations within the 3-D fabric, where the electrically conductive system/device should be integrated. Yet, according to 6 another object of this invention, an electrically conductive system/device, depending on 7 its intended functional designation, can be either left bare without a host tow (e.g. by 8 using the substitution approach) or being encapsulated within the necessary amount of 9 insulating fibers of its host tow (e.g. by using the addition approach).
With no doubt, the capability of using 3-D fabrics as the carriers of various conducting 11 systems/devices/networks far exceeds the capability of 2-D fabrics and will inspire new 12 efficient solutions.
i3 Other technicalities of the invention in the parts of manufacturing 3-D
fabrics, 14 preforms and composites, will be clear to those skilled in the art, after getting familiar with the illustrations, their detailed description, and several reduction to practice 16 . examples.
17 The systems, devices, and/or networks integrated with the preform of the present 18 invention are generally not required to provide any structural function within the preform, 19 although they may optionally do so in particular embodiments.
In one embodiment of the present invention, optical fibers are integrated within 21 the fabric preform of the present invention prior to composite formation, where the 22 preform is intended for later use as a composite material or component.

1 . Both optical capabilities and structural characteristics may be enhanced by using 2 ribbons or bundles of fibers in place of single, discrete fibers integrated with the fabric 3 preform of the present invention. Ribbons may comprise parallel strands for scanning 4 devices, or interlaced strands to add structural integrity to the composite.
Alternatively, interwoven bundles may be employed for structural purposes or to provide large cross 6 section optical paths for illumination energy to be conducted from remote light sources to 7 areas where illumination is desired for enhancing vision.
8 The present invention further includes a method for forming a 3-D preform for 9 composites including the steps of providing yarn system component for forming a three-dimensional engineered fiber preform formed by intersecting textile system components;
11 and providing at least one system, device, andlor network integrated with the preform for 12 providing a predetermined function, wherein the at least one system, device, and/or 13 network is introduced prior to formation of a composite structure including the preform, 14 thereby providing a 3-D fabric preform for composites. Additional steps may include introducing device/network materials to the textile system supply for integration with the 16 preform in at least one fiber or pathway of they network materials; and producing the 17 preform via a textile processing system; thereby producing a 3-D fabric having integrated 1 ~ networks/devices therein. Furthermore, the at least one fiber or pathway of the network 19 materials, device and/or sensors may either be a substantially straight pathway, as in the case of optical fibers, especially glass fibers, or the at least one fiber or pathway may be 21 flexible, as in the case of a flexible material/fiber where a non-straight pathway, e.g., an 22 electrical circuit or network produced by integration of a plurality of convoluted 23 pathways having predetermined intersection or contact points. Importantly, the method 1 of the present invention provides for the introduction of the systems, devices, and/or 2 networks and integratiori thereof with the preform prior to any composite formation steps, 3 which obviously are intended to occur after the integration of the components with the 4 . preform according to the present invention where the preform is intended for use as a composite material.
6 ~ Other method steps may be included or substituted without departing from the 7 scope of the present invention, depending upon the particular systems, devices, andlor 8 networks and combinations thereof that are integrated with the 3-D fiber preform and the 9 application for the composite material that may ultimately be formed therewith.
The systems, devices, and/or networks integrated with the preform of the present 11 invention are generally not required to provide any structural function within the preform, 12 although they may optionally do so in particular embodiments.
13 . In one embodiment of the present invention, optical fibers are integrated within 14 the fabric preform of the present invention prior to composite formation, where the preform is intended for later use as a composite material or component.
16 Both optical capabilities and structural characteristics may be enhanced by using 17 ribbons or bundles of fibers in place of single, discrete fibers integrated with the fabric 18 preform of the.present invention. Ribbons may comprise parallel strands for scanning 19 devices, or interlaced strands to add structural integrity to the' composite. Alternatively, interwoven bundles may be employed for structural purposes or to provide large cross 21 section optical paths for illumination energy to be conducted from remote light sources to 22 areas where illumination is desired for enhancing vision.

1 Regarding conductive materials, a conductor may comprise single- or multi-2 stranded wires, and suitable materials include stainless steel, tinned copper or carbon 3 fiber.
4 Regarding applications wherein a structural component has piezoelectric fiber composite the structural layers are made, for example, of standard carbon fiber reinforced 6 composite material. Preferred embodiments include epoxy polymers, which are 7 chemically and mechanically compatible with the polymers in the host composite 8 structures, i.e., the piezoelectric composite epoxy is bondable to the structural composite 9 epoxy and has similar mechanical and electrical properties. Preferably, the conductive layers are in direct contact with the fibers. The conductive electrode layers are relatively 11 flexible. Thin metal layers are desirable, because they do not restrain the composite of the 12 structural component during actuation. Silver is preferred. Other metals, which may be 13 used, include aluminum, copper, and gold, as well as non-metallic conductors such as 14 conductive polymers. In embodiments, the electrode layers may be formed of a thin polymer substrate coated with an ultra-thin layer of metal. The electrodes may be etched 16 in a pattern. The electrode layers may adhere directly to structural materials.
17 The composites may be used in many structural components. For example, in 18 aeroelastic structures for active control of composite wings to suppress flutter at high 19 airspeeds by applying AC fields, thereby effectively increasing the top speed of an aircraft. The composites can be used for both sensing and actuation in a closed-loop 21 configuration. The anisotropic nature .of piezoelectric displacement can be maximized by 22 choosing a polymeric material and piezoelectric ceramic material, which have large 23 differences in their mechanical stiffnesses.

1 In the embodiment where a health monitoring system is used with the present 2 invention, it may be based on the use of vibration signature of the structure to determine 3 its mechanical and thermal state. Sensor modules are located throughout the structure and 4 are connected to the host CPU by the high speed databus, by way of example and not limitation. A principle underlying the operation of a Health Monitoring System (HMS) 6 of the present invention is the use of specimen vibration signatures to determine 7 mechanical and thermal properties. A specimen vibration signature is derived from the 8 dynamic response or reaction. of the structure to a stimulus. Such dynamic response 9 typically is the varying electrical output of transducers attached to the structure. The HMS applies this concept to obtain dynamic response characteristics corresponding to 11 failure or damage of structural components. Specifically, HMS mechanically excites the 12 structure and monitors its dynamic response through sensors or feedback transducers. The 13 excitation energy is preferably in the form of a single pulse, which generates a wideband 14 frequency range of vibration of the structure. The feedback transducers are preferably piezoelectric film transducers. ~ Pattern recognition techniques are used to process 16 vibration signals and classify the type and location of structural damage.
In addition to 17 the pattern recognition techniques, key components of the overall HMS
include 18 intelligent sensor modules, a host central processing unit (CPU), and a high speed 19 databus. . The sensor module contains an actuation mechanism to generate a physical impulse and apply it to the structure, and feedback transducers and signal processing 21 circuitry to detect the corresponding vibration signals, process them, and transmit the 22 preferably digitized data to the host CPU when queried. The sensor module is also 23 provided with an embedded processor for controlling the actuation mechanism as well as 1 for data acquisition. The host CPU executes pattern recognition software which 2 distinguishes among fatigue cracks, rivet line failure, ice or material buildup on the 3 structure, and other disturbances.
4 Desi ng_ Example(s) This section outlines a few design examples, not necessarily optimized or 6 ~ intended to limit the scope of the invention thereto, but illustrative of what can be done 7 for a fabric preform having integrated systems, devices, and/or networks according to the 8 present invention, wherein the systems, devices, and/or' networks are integrated with the 9 preform prior to composite formation, where the fabric is intended for later composite applications. These design examples include, but are not limited to, the following:
11 In the practical implementation of the present invention, various embodiments 12 may be constructed using a range and combination of many types of system or device 13 materials according to the desired function of the complete system or device within the 14 fabric or composite structure/part made with it. Combinations of passive, active, conductive, fluidic conduit, optical conduit and many more may be employed so to 16 achieve the desired functions. Among the most commonly desired features of diagnostics 17 and health monitoring of a structure or part is to determine, measure, or monitor the 18 strain, stress, damage, delamination, cracks, temperature, moisture, acceleration, and 19 other performance characteristics, which are usually hidden in the interior of the materials or in parts of the structure which are difficult to access for inspection, as was 21 described in section "BACKGROUND OF THE INVENTION". This is one of many 22 applications referred to as smart materials or smart structures. Current application of 23 optical sensors in aircraft and spacecraft requires bonding optical sensors to the surfaces, 1 or embedding them between plies of a laminated composite. This leaves delicate fibers 2 exposed, the fibers may move during infusion or curing, and may induce delamination 3 along the delicate bond line between the laminate plies.
4 Several prototypes of embodiment of the present invention have been demonstrated toward this particular purpose. It should be noted that the prototypical 6 demonstrations are not exhaustive but rather exemplary of modifications to composite 7 construction methods and might be considered a sub-element of a larger composite 8 structure or vehicle such as a fuselage section, hull skin, wing panel, composite beam or 9 strut within a boat or aircraft, windmill blade, or rotor shaft among others.
Continuous supply of warp (axial) optical fiber from creels or beams has proven 11 to be quite suitable in automation. Likewise, continuous optical fibers were placed uncut 12 repeatedly, back and forth, across the width of the preform in the weft direction at several 13 levels forming a regular grid. The transmitted light intensity was measured during 14 weaving-and efficiencies found to be suitable. Experimental data collected from tested specimens allowed mapping strains and clearly indicated internal strain gradients near 16 stress risers and loading sites.
17 Manufacture of said smart structure prototypes included the accomplishment of 18 several step-wise tasks. Automated production of preforms for composite materials 19 instrumented with fiber optic sensors has been performed. Optical fibers and sensors have been integrated into 3-D woven and 3-D braided preforms by addition, and substitution, 21 both before and after initial preform fabric formation. Continuous automated integration 22 of optical fibers into 3-D weaving process during fabric formation was performed, 23 sensors of both rigid and flexible types were integrated into 3-D fabrics, several methods 1 were utilized to mark and map optical fiber and sensor positions within composites, 2 demonstration of various methods of connection to the optical systems have been applied 3 and refined, and testing of composite coupons instrumented with large number of 4 integrated sensors has yielded useful data quantifying the internal strain state of the material.
6 In one particular demonstration, eleven spools were wound with one optical fiber 7 each having acrylic coating, the bound end of each was connected to by fusion slicing, 8 whereupon those same spools were mounted in a creel, and in filling stands, along with 9 hundreds . of other spools having variously carbon, glass, or Kevlar tows arranged to supply the weft, warp, and z yarns to a loom for producing a multi-layer 3-D
woven 11 hybrid fabric. The free end of each optical fiber was passed through standard, or modified 12 guides so as to merge with selected base fabric structural fibers in the warp, weft, and z 13 directions within the fabric. Those optical fibers added to the weft supply merged with 14 the weft yarns near the tips of the rapiers used by the machine during insertion of weft yarns during the process of weaving and passed through the final rapier eyelets as an 16 integral part of the weft yarn at that point during weaving. The z yarns were passed 17 through particularly chosen heddles and followed those harness motions during weaving.
18 A laser detector was connected to the optical fibers near the fell of the fabric at the loom 19 after the optical fibers were teased from their parent and carrier structural fibers. Laser light was injected into the optical fibers at the supply spool, and the intensity of the light 21 transmitted was documented during weaving as all effects of the weaving system and the 22 effects of integration in the fabric accumulated. Light transmission was found to be 23 suitable, efficient, and particularly so in the straight, in-plane weft-directional optical 1 fibers. Results of weaving trials showed that transmission efficiencies are nearly 2 unaffected by the fiber path in the warp and weft directions within the fabric. Losses do 3 occur at tight bends in the z-directional fibers at the bends seen at the top and bottom 4 surfaces, though those losses may be mitigated by manipulation of the z yarn paths and choice of fiber and signal types.
6 In another demonstration, one E-glass 3-D braided preform was produced 7 containing 4 optical fibers incorporated in axial tows. Transmission efficiency was 8 measured after braiding. Not surprisingly, the losses in the practically straight axial fibers 9 were very low.
In another demonstration, at least 9 EFPI fiber optic sensors with 830nm optical 11 fiber leads were integrated into an 8-weft and 7-warp layer 3-D woven carbon fiber 12 preform during weaving on a digitally controlled automated 3-D weaving machine. The 13 rigid .sensors and their flexible leads were carried into the fabric along with the regular 14 carbon fiber material iri the weft direction periodically, and in several of the 8 weft layers within the .8 inch thick multi-layer fabric. The preform was cut in the weft direction 16 down to nominally 12"x18". Each of the fibers having one EFPI sensor along their length 17 passed across the preform intimately with one carbon weft yarn yielding a preform with 9 18 EFPI sensors at several depths through the fabric. Additionally, during momentary pauses 19 of the loom, several EFPI sensors were placed through the thickness of the fabric by lowering them through the z corridor at the fell until stopped by a tape flag adhered at a 21 known location leaving the EFPI suspended at a known depth in the fabric when the loom 22 was released, and the fabric continued to form. Also, certain of the sensor/fiber 23 assemblies had FC type connectors applied prior to weaving and as such, those .

1 connectors were integrated into the fabric and were located at the selvedge of the same.
2 The ends of the sensing fibers were left long, extending as if fringe beyond the edges of 3 the fabric, and the z axis sensor leads were bent 90 degrees at the surface and integrated 4 into the topmost weft yarn until they reached the edge of the fabric.
The 3-D carbon fiber preforms were placed under a simple vacuum bag on a flat 6 surface with an olefin platen on top, and with vacuum grease packed into the connectors 7 to exclude resin from them, while the free ends of the optical fibers were sleeved with a 8 small flouro-polymer tubes, and passed across and shallowly embedded in the mastic 9 vacuum seal. The preform was infused with an epoxy modified vinyl-ester resin, cured at room temperature, removed from the bag, and post-cured for several hours at 250F per 11 the resin manufacturers recommendations. Three instrurnented test coupons were cut 12 from different sections of the same panel. Connections to those fiber ends left free were 13 made by cleaving, and fusion splicing of FC connecterized 1550nm SMF leads, using a 14 Fujikura semi-automated splicer. Connection to those fibers with the connectors woven in were made by rinsing out the grease, and mating with the corresponding male FC
16 connector to the interrogation system. Finally, resistive foil strain gauges were adhered to 17 the surfaces as references, and the internally instrumented composite specimen was 18 mechanically tested in 4-point bending. The optical sensors were, interrogated during 19 loading by commercially available demodulation systems. Strains at several points within the composite beams were displayed in real time duxing loading, and clearly reflected 21 internal strain gradients within the composite material near stress risers and loading sites.
22 In another demonstration, at least 16 EFPI fiber optic sensors with 830nm optical 23 fiber leads were integrated into a 7 weft x 6 warp layer 3-D woven carbon fiber preform 1 during weaving on a digitally controlled automated 3-D weaving machine. The rigid 2 sensors and their flexible leads were carried into the fabric along with the regular carbon 3 fiber material in the weft direction periodically, and in several of the 7 weft layers within 4 the .5 inch thick multi-layer fabric. The preform was cut in the weft direction. Each of the fibers had one EFPI sensor along their length passed across the preform intimately with 6 one carbon weft yarn yielding a preform with 9 EFPI sensors at several depths through 7 the thickness. Additionally, during momentary pauses of the loom, several EFPI sensors 8 were placed through the thickness of the fabric by inserting them through the z corridor at 9 the fell until stopped by a tape ' flag adhered at a known location, leaving the EFPI
suspended at a known depth in the fabric when the loom was released, and the fabric 11 continued to form. Also, certain of the sensorlfiber assemblies had, FC
type connectors 12 applied prior to weaving, and as such, those connectors were integrated into the fabric 13 and were located at the selvedge of the same. The ends of the sensing fibers were left 14 long, extending as if fringe beyond the edges of the fabric, and the z axis sensor leads were bent 90 degrees at the surface and integrated into the topmost weft yarn until they 16 reached the edge of the fabric.
17 The 3-D carbon fiber preforms were placed under a simple vacuum bag on a flat 18 surface with an olefin platen on top, while the free ends of the optical fibers were sleeved 19 with a small flouro-polymer tubes, and passed across and shallowly embedded in the mastic vacuum seal. The preform was infused with an epoxy modified vinyl-ester resin, 21. cured at room temperature, removed from the bag, and post-cured for several hours at 22 250F per the resin manufacturers recommendations. Three instrumented test coupons 23 with special notch-like features were milled from the same panel using carbide cutters.

1 Connections to those fiber ends left free were made by cleaving, and fusion splicing of 2 FC connecterized leads, using a semi-automated splicer. Finally, resistive foil strain 3 gauges were adhered to the surfaces as references, and the internally instrutriented 4 composite specimen was mechanically tested in tension. The ' EFPI sensors were interrogated during loading by commercially available demodulation systems.
Strains in 6 the test direction and through thickness at several points within the composite beams 7 were monitored using the sensors in real time during loading, and clearly indicated 8 internal strain gradients near the notches.
9 ~ another demonstration, at least ten flexible DSS brand optical fibers manufactured by Luna Innovations were integrated into a previously formed 3-D
woven 11 carbon fiber preform in the weft direction by attaching the optical fibers to duplicates of 12 the selected host yarns, fastening the joined pair to the selected host yarn and pulling out 13 the host, thereby replacing the regular yarn with the instrumented yarn.
This was 14 performed periodically, and in five of the nine layers within the .235 inch thick multi-layer fabric, which had been cut to nominally 12"x18". Each of the optical fibers having 16 multiple Bragg gratings each Smm long and paced every lOmm along the fiber length 17 passed across the preform intimately with one carbon weft yarn, returned with another 18 and so on, yielding a preform with more than 360 Bragg grating sensors within the 19 confines of the preform. The ends of the sensing fibers were left long, extending as if fringe beyond the edges of the fabric. The 3-D carbon fiber preforms were then placed 21 under a simple vacuum bag on a flat surface while the free ends of the optical fibers were 22 sleeved with a small flouro-polymer tubes, and passed across and shallowly embedded in 23 the mastic vacuum seal. The preform was infused with an epoxy modified vinyl-ester 1 resin, cured at room temperature, removed from the bag, and post-cured for several hours 2 at 250F per the resin manufacturers recommendations. Connections were made by 3 cleaving, and fusion splicing of FC connecterized 1550nm SMF leads, using a Fujikura 4 semi-automated splicer. Notches were machined into certain specimens after elastic testing with '/z hole at each edge, thus inducing a strain gradient. Finally, resistive foil 6 strain gauges were adhered to the surfaces as references, and the internally instrumented 7 composite specimens were mechanically tested in 4-point bending. The Bragg gratings 8 were interrogated during loading by commercially available demodulation equipment 9 produced by Luna Innovations. Strains at hundreds of points were displayed in real time during loading, and clearly indicated internal strain gradients near stress risers and 11 loading sites.
12 In another demonstration, at least eighteen flexible DSS brand optical fibers 13 manufactured by Luna Innovations were integrated into a previously formed 3-D woven 14 carbon fiber preform in the weft direction periodically, and in five of the nine layers within the 0.235 inch thick mufti-layer fabric which had been cut to nominally 12"x24".
16 Each of the optical fibers having multiple Bragg gratings each Smm long and spaced 17 every lOrnm along their length passed across the preform intimately with one carbon weft 18 yarn, returned with another and so on, yielding a preform with more than 550 Bragg 19 grating sensors within the confines of the fabric. The ends of the sensing fibers were left long, extending as if fringe beyond the edges of the fabric. The 3-D carbon fiber preforms 21 were placed under a simple vacuum bag on a flat surface, while the free ends of the 22 optical fibers were sleeved with a small flouro-polymer tubes, and passed across and 23 shallowly embedded in the mastic vacuum seal. The preform was infused with an epoxy 1 modified vinyl-ester resin, cured at room temperature, removed from the bag, and post-2 cued for several hours at 250F per the resin manufacturers recommendations.
Two 3 sensor instrumented, and two sensor-free coupons were cut from different sections of the 4 same panel and bonded to form a double-lap joint specimen using epoxy adhesive.
Connections were made by cleaving, and fusion splicing of FC connecterized 1550nm 6 SMF leads, using a Fujikura semi-automated splicer. Next, resistive foil strain gauges 7 were adhered to the surfaces as references, and the internally instrumented double-lap 8 ~ composite bonded joint specimen was mechanically tested in tension. The Bragg gratings 9 were interrogated during loading by commercially available demodulation equipment produced by Luna Innovations. Strains at hundreds of points were displayed in real time 11 during loading.
12 Certain modifications and improvements will occur to those skilled in the art upon 13 a reading of the foregoing description. All modifications and improvements have been 14 deleted herein for the sake of conciseness and readability but are properly within the scope of the following claims.

Claims

1. A 3-D fabric or preform for composites comprising:
a three-dimensional engineered fiber preform formed by intersecting yarn system components; and at least one system, device, and/or network integrated with the preform for providing a predetermined function, wherein the at least one system, device, and/or network is introduced prior to formation of a composite structure including the preform, thereby providing a 3-D fabric preform for composites.

2. The preform according to claim 1, wherein the at least one system, device, and/or network is introduced at or during the fabric-forming process.

3. The preform according to claim 1, wherein the at least one system, device, and/or network is introduced after the fabric-forming process, but prior to the formation of the composite or other application of the fabric.

4. The preform according to claim 2, wherein the at least one system, device, and/or network is integrated with the preform while the preform is being formed on a machine.

5. The preform according to 1, wherein the at least one system, device, and/or network is automatically integrated with the preform.

6. The preform according to claim 1, wherein the at least one system, device, and/or network is manually integrated with the preform.

7. The preform according to claim 1, wherein the preform is formed from a 3-D
woven fabric.

8. The preform according to claim 1, wherein the preform is formed from a 3-D
orthogonally woven fabric.

9. The preform according to claim 1, wherein the preform is formed from a 3-D
braided fabric.

10. The preform according to claim 1, wherein the preform is formed from a 3-D
multiaxial fabric.

11. The preform according to claim 1, wherein the at least one system, device, and/or network includes at least one sensor.

12. The preform according to claim 11, wherein the at least one sensor is selected from the group consisting of fiber optic sensors, piezoelectric sensors, temperature sensors, pressure sensors, piezomagnetic sensors, electrically conductive sensors, hydraulic sensors, and combinations thereof, and combinations thereof.

13. The preform according to claim 1, wherein the at least one system, device, and/or network includes electrically conductive components.

14. The preform according to claim 1, wherein the components include electrically conductive components aimed at telecommunication, data transmission, electromagnetic reception, electromagnetic transmission, electromagnetic diffusion/diffraction, electromagnetic shielding of electronic equipment, personnel protection against electromgnetic radiation, and other similar functions which are distinct from the functions of sensing and actuation.

15. The preform according to claim 1, wherein the at least one system, device, and/or network includes at least one actuator.

16. The preform according to claim 1, wherein the at least one system, device, and/or network includes at least one transducer.

17. The preform according to claim 1, wherein the at least one system, device, and/or network includes at least one diagnostic system, device, or network.

18. The preform according to claim 17, wherein the at least one system, device, and/or network includes at least one fabric diagnostic system, device, or network.

19. The preform according to claim 1, wherein the at least one system, device, and/or network includes at least one magnetic component.

20. The preform according to claim 1, wherein the at least one system, device, and/or network includes at least one component for releasing a medication.

21. The preform according to claim 1, wherein the at least one system, device, and/or network includes at least one component for repairing the preform.

22. The preform according to claim 1, wherein the at least one system, device, and/or network includes at least one audio component.

23. The preform according to claim 1, wherein the at least one system, device, and/or network includes at least one video component.

24. The preform according to claim 1, wherein the at least one system, device, and/or network includes at least one receiver and/or transmitter components.

25. The preform according to claim 1, where the 3-D fabric or preform is to be used for its own purpose or without being included in further composite processes.

26. The preform according to claim 1, wherein the preform is formed from a 3-D
multiaxial woven fabric incorporating more than three directions of fibers/tows, where at least one of them is oriented at an angle to the direction of fabric formation.

27. The preform according to claim 1 wherein the network forms a circuit for the transmission of fluids, electricity, or light.

28. The preform according to claim 1 wherein the network forms a circuit for the transmission of fluids, electricity, or light and which performs logical functions.

29. The preform according to claim 1, wherein the preform is formed from/as a warp-knitted fabric.

30. The preform according to claim 1, wherein the at least one system, device, and/or network includes at least one optical fiber.

31. The preform according to claim 1, wherein the at least one system, device, and/or network includes at least one piezoelectric fiber or other piezoelectric object substantially extended in one direction.

32. The preform according to claim 1, wherein the at least one system, device, and/or network includes at least one shape memory alloy fiber or other shape memory alloy object substantially extended in one direction.

33. The preform according to claim 1, wherein the at least one system, device, and/or network includes at least one tubular , hollow, or microchannel fiber, rod, or filament.

34. A method for forming a 3-D preform for composites comprising the steps of providing yarn system component for forming a three-dimensional engineered fiber preform formed by intersecting textile system components; and providing at least one system, device, and/or network integrated with the preform for providing a predetermined function, wherein the at least one system, device, and/or network is introduced prior to formation of a composite structure including the preform, thereby providing a 3-D fabric preform for composites.

35. The method according to claim 34, further including the steps of:
introducing device/network materials to the textile processing system supply for integration with the preform in at least one fiber or pathway of the network materials;
producing the preform via a textile processing system; thereby producing a 3-D
fabric having integrated networks/devices therein.

36. The method according to claim 35, wherein the at least one fiber or pathway of the network materials, device and/or sensors is a substantially straight pathway.

37. The method according to claim 35 wherein the at least one fiber or pathway is flexible.

38. The method according to claim 35 wherein the at least one fiber or pathway is rigid.

39. A polymer matrix composite material which is manufactured with the utilization of the preform according to claim 1 using any suitable room temperature or elevated temperature composite fabrication technique.

40. A ceramic matrix, metal matrix and/or carbon matrix composite material which is manufactured with the utilization of the preform according to claim 1 using any suitable processing technique, with the selection of the system, device, and/or network able to maintain its functionality in a respective high temperature processing and/or in-service environment.