3D composites

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Three-dimensional composites use fiber preforms constructed from yarns or tows arranged into complex three-dimensional structures. These can be created from a 3D weaving process, a 3D knitting process, a 3D braiding process, or a 3D lay of short fibers. A resin is applied to the 3D preform to create the composite material. Three-dimensional composites are used in highly engineered and highly technical applications in order to achieve complex mechanical properties. Three-dimensional composites are engineered to react to stresses and strains in ways that are not possible with traditional composite materials composed of single direction tows, or 2D woven composites, sandwich composites or stacked laminate materials.

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3D Woven Composites

Three dimensional woven fabrics are fabrics that could be formed to near net shape with considerable thickness. There is no need for layering to create a part, because a single fabric provides the full three-dimensional reinforcement. The 3-D woven fabric is a variant of the 2D weaving process, and it is an extension of the very old technique of creating double and triple woven cloth. 3D weaving allows the production of fabrics up to 10 cm in thickness. [1] Fibers placed in the thickness direction are called z-yarn, warp weaver, or binder yarn for 3D woven fabrics. More than one layer of fabric is woven at the same time, and z-yarn interlaces warp and woof yarns of different layers during the process. At the end of the weaving process, an integrated 3D woven structure, which has a considerable thickness, is produced. [2] Three-dimensional woven structures can create composite materials with fiber volume fractions around 50% in both 3D unit cell and 3D orthogonal structures. [3]

Angle-interlock three-dimensional woven structures are also common in order to create much thicker woven preforms. In the interlock structures yarns can be woven from one layer of yarns to another and then back to the original layer to lock adjacent layers to each other. In complex interlock structures yarns may be woven at specified points into several layers in order to join multiple layers. These structures have a great advantage over laminated materials because of their excellent resistance to layer delamination. [4]

By using jacquard woven techniques such as bifurcation, the 3D woven preforms can be created into nearly endless shapes ranging from a standard I-Beam to a complex Sine-Curve I-Beam, to Aircraft Airfoils, and many other shapes. 3D woven composites, finished with resin transfer molding have been produced larger than 26 feet long. [5]

3D woven composites are used for various engineering applications, including engine rotors, rocket nose cones and nozzles, engine mounts, aircraft framework, T- and X-shape panels, leading edges for aircraft wings, and I-Beams for civil infrastructure. [6]

Classification of 3D woven fabrics

There are several types of 3D woven fabrics that are commercially available; they can be classified according to their weaving technique. [7]

  1. 3D woven interlock fabrics, are 3D woven fabrics produced on a traditional 2D weaving loom, using proper weave design and techniques, it could either have the weaver/z-yarn going through all the thickness of the fabric or from layer to layer.
  2. 3D orthogonal woven fabrics, are 3D woven fabrics produced on a special 3D weaving loom. The process to form such fabric was patented by Mohamed and Zhang. [8] The architecture of the 3D orthogonal woven fabric consists of three different sets of yarns; warp yarns (y-yarn), weft yarns (x-yarn), and (z-yarn). Z-yarn is placed in the through-thickness direction of the preform. In 3D orthogonal woven fabric there is no interlacing between warp and weft yarns and they are straight and perpendicular to each other. On the other hand, z-yarns combine the warp and the weft layers by interlacing (moving up and down) along the y-direction over the weft yarn. Interlacing occurs on the top and the bottom surface of the fabric. [9] [10]

Advantages

3D Braided Composites

"3D braided fabrics technology is an extension of the well-established 2-D braiding technology wherein the fabric is constructed by the intertwining of two or more yarn systems to form an integral structure." [13] Developed in the late 1960s, in an effort to circumvent the problems related to 2D composite laminates yet at the same time retain the benefits of the braiding process. [14] Braided structures, used as composite preforms, have a number of advantages over other competing processes, such as filament winding and weaving. [15]

Braided composites have superior toughness and fatigue strength in comparison to filament wound composites. Woven fabrics have orthogonal interlacement while the braids can be constructed over a wide range of angles, from 10 to 858. An additional set of axial yarns can be introduced to the braiding process to produce triaxial braids (Fig. 1); triaxial braids are more stable and exhibit nearly isotropic properties.

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Braids can be produced either as seamless tubes or flat fabrics with a continuous selvedge. Composites produced with the braided preforms exhibit superior strength and crack resistance in comparison to broadcloth composites, due to fiber continuity; Composites with braided holes (Fig.2) exhibit about 1.8 times the strength in comparison to drilled holes, again due to fiber continuity.

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There are two main types of 3D braiders, horn gear and track and column types. Horn gear type 3D braiders use a large number of traditional horn gears for carrier propulsion. By arranging the horn gears in a square, 3D solid braids with a variety of cross-sections (e.g. H section) can be produced. [16] [17]

Applications of 3D Braided Composites

3D Stitched Composites

The stitching of laminates in the through thickness direction with a high strength thread has proven a simple, low-cost method for producing 3-D composites. The stitching process basically involves sewing high tensile strength yarn (e.g. glass, carbon or Kevlar®), through an uncured prepreg laminate or dry fabric plies using an industrial sewing machine. [18] [19]

Studies report an improvement to in-plane mechanical properties due to stitching, whereas others find unchanged or degraded properties.The data assembled for stitched laminates reveal that the tension, compression, flexure, shear and open-hole strengths are improved or degraded up to 20% by stitching relative to those of unstitched laminates. [20]

Applications of 3D Stitched Composites

3D Z-Pinning

This alternative method to the standard stitching process was first introduced in the late 1980s and was commercially developed by the company Aztex as Z-Fiber™ technology. "This technology consists of embedding previously cured reinforcement fibers into a thermoplastic foam that is then placed on top of a prepreg, or dry fabric, lay-up and vacuum bagged." 12 The foam will collapse as temperature and pressure are increased, which allows the fibers to be slowly pushed into the lay-up. 3D reinforcement in regards to Z-pinning is necessary to introduce a mechanical link between the different plies of the composite lamina, this link being a stiff carbon fiber rod in Z-pinning. Z-pin (carbon fiber of small diameter embedded in the thickness direction-z) composites are a means to provide higher through-the-thickness stiffness and strength that 2D woven composites do not possess.

Application of 3D Z-Pinned Composites

Resin Application to Three-Dimensional Preforms

Many Three-Dimensional preforms are transformed into complex composite materials when a resin is applied and cured within the preform to create a solid fiber reinforced matrix. The most common form of resin application for 3D preforms is the Resin Transfer Molding process where a mold is created in the shape of a preform and the preform is then placed inside. The mold is closed and then the resin of the matrix material is injected under particular temperature and pressure, then allowed to cure. the mold is then removed from the exterior of the 3D composite material. [20]

Mechanical Evaluation of 3D Composites vs. 2D Composites

The microstructure of a 3D woven composite is mainly determined by the fiber architecture to the woven preform and weaving process, and to a lesser extent by the process of consolidation.Various types of defects are inadvertently created during the 3D weaving process that can possibly degrade the in-plane, through-thickness, and impact properties of the 3D composite. Research has found that testing various 3D composite materials that " ...the strength is the same or slightly higher than an equivalent two-dimensional (2D) material." When compared to a 2D composite, the impact resistance, compression after impact (CAI), and delamination control is significantly improved with a 3D composite without significantly reducing the mechanical properties along the plane. [21]

Related Research Articles

Textile Material produced by twining, weaving, felting, knotting, or otherwise processing natural or synthetic fibers

A textile is a flexible material made by creating an interlocking network of yarns or threads, which are produced by spinning raw fibres into long and twisted lengths. Textiles are then formed by weaving, knitting, crocheting, knotting, tatting, felting, bonding or braiding these yarns together.

Composite material Material made from a combination of two or more unlike substances

A composite material is a material produced from two or more constituent materials with notably dissimilar chemical or physical properties that, when merged, create a material with properties unlike the individual elements. The individual components remain separate and distinct within the finished structure, distinguishing composites from mixtures and solid solutions.

Carbon fibers Material fibers about 5–10 μm in diameter composed of carbon

Carbon fibers or carbon fibres are fibers about 5 to 10 micrometers (0.00020–0.00039 in) in diameter and composed mostly of carbon atoms. Carbon fibers have several advantages including high stiffness, high tensile strength, low weight, high chemical resistance, high temperature tolerance and low thermal expansion. These properties have made carbon fiber very popular in aerospace, civil engineering, military, and motorsports, along with other competition sports. However, they are relatively expensive when compared with similar fibers, such as glass fibers or plastic fibers.

Fiberglass, or fibreglass is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet, or woven into a fabric. The plastic matrix may be a thermoset polymer matrix—most often based on thermosetting polymers such as epoxy, polyester resin, or vinylester—or a thermoplastic.

Satin Smooth, lustrous fabric, usually of silk or synthetic fiber, woven with a long-float satin binding in warp or weft

Satin refers to the weave of a fabric rather than the material. It typically has a glossy surface and a dull back, one of three fundamental types of textile weaves along with plain weave and twill. The satin weave is characterized by four or more fill or weft yarns floating over a warp yarn, four warp yarns floating over a single weft yarn. Floats are missed interfacings, for example where the warp yarn lies on top of the weft in a warp-faced satin. These floats explain the high luster and even sheen, as unlike in other weaves, the light reflecting is not scattered as much by the fibres. Satin is usually a warp-faced weaving technique in which warp yarns are "floated" over weft yarns, although there are also weft-faced satins. If a fabric is formed with a satin weave using filament fibres such as silk, polyester or nylon, the corresponding fabric is termed a satin, although some definitions insist that the fabric be made from silk. If the yarns used are short-staple yarns such as cotton, the fabric formed is considered a sateen.

Fibre-reinforced plastic (FRP) is a composite material made of a polymer matrix reinforced with fibres. The fibres are usually glass, carbon, aramid, or basalt. Rarely, other fibres such as paper, wood, or asbestos have been used. The polymer is usually an epoxy, vinyl ester, or polyester thermosetting plastic, though phenol formaldehyde resins are still in use.

Metallic fiber Thread wholly or partly made from metal

Metallic fibers are manufactured fibers composed of metal, metallic alloys, plastic-coated metal, metal-coated plastic, or a core completely covered by metal.

Filament winding is a fabrication technique mainly used for manufacturing open (cylinders) or closed end structures. This process involves winding filaments under tension over a rotating mandrel. The mandrel rotates around the spindle while a delivery eye on a carriage traverses horizontally in line with the axis of the rotating mandrel, laying down fibers in the desired pattern or angle. The most common filaments are glass or carbon and are impregnated in a bath with resin as they are wound onto the mandrel. Once the mandrel is completely covered to the desired thickness, the resin is cured. Depending on the resin system and its cure characteristics, often the rotating mandrel is placed in an oven or placed under radiant heaters until the part is cured. Once the resin has cured, the mandrel is removed or extracted, leaving the hollow final product. For some products such as gas bottles, the 'mandrel' is a permanent part of the finished product forming a liner to prevent gas leakage or as a barrier to protect the composite from the fluid to be stored.

Warp knitting

Warp knitting is a family of knitting methods in which the yarn zigzags along the length of the fabric; i.e., following adjacent columns, or wales, of knitting, rather than a single row, or course. For comparison, knitting across the width of the fabric is called weft knitting.

Pultrusion is a continuous process for manufacture of spendere materials with constant cross-section. The term is a portmanteau word, combining "pull" and "extrusion". As opposed to extrusion, which pushes the material, pultrusion pulls the material.

The manufacture of textiles is one of the oldest of human technologies. To make textiles, the first requirement is a source of fibre from which a yarn can be made, primarily by spinning. The yarn is processed by knitting or weaving, which turns yarn into cloth. The machine used for weaving is the loom. For decoration, the process of colouring yarn or the finished material is dyeing. For more information of the various steps, see textile manufacturing.

Ripstop

Ripstop fabrics are woven fabrics, often made of nylon, using a special reinforcing technique that makes them resistant to tearing and ripping. During weaving, (thick) reinforcement yarns are interwoven at regular intervals in a crosshatch pattern. The intervals are typically 5 to 8 millimeters. Thin and lightweight ripstop fabrics have a 2-dimensional structure due to the thicker yarns being interwoven in thinner cloth. Older lightweight ripstop fabrics display the thicker interlocking thread patterns in the material quite prominently, but more modern weaving techniques make the ripstop threads less obvious. A similar effect can be achieved by weaving two or three fine yarns together at smaller intervals.

In architecture, fabric structures are forms of constructed fibers that provide end users a variety of aesthetic free-form building designs. Custom-made fabric structures are engineered and fabricated to meet worldwide structural, flame retardant, weather-resistant, and natural force requirements. Fabric structures are considered a sub-category of tensile structure.

Textile-reinforced concrete

Textile-reinforced concrete is a type of reinforced concrete in which the usual steel reinforcing bars are replaced by textile materials. Instead of using a metal cage inside the concrete, this technique uses a fabric cage inside the same.

Carbon fiber reinforced polymer, Carbon fibre reinforced polymer, or carbon fiber reinforced plastic, or carbon fiber reinforced thermoplastic, is an extremely strong and light fiber-reinforced plastic which contains carbon fibers. The spelling 'fibre' is typically used outside the US. CFRPs can be expensive to produce, but are commonly used wherever high strength-to-weight ratio and stiffness (rigidity) are required, such as aerospace, superstructures of ships, automotive, civil engineering, sports equipment, and an increasing number of consumer and technical applications.

In the field of composite materials, tufting is an experimental technology to locally reinforce continuous fibre-reinforced plastics along the z-direction, with the objective of enhancing the shear and delamination resistance of the structure.

Spread tow fabric (stf) is a type of lightweight fabric. Its production involves the steps of spreading a tow in thin and flat uni-directional tape, and weaving the tapes to a Spread Tow Fabric. This technique increases the mechanical properties of the material and is also used to reduce weight on composites. Manufacturers of Spread Tow Tapes include Oxeon AB, Teknomax Corp., Harmoni Industry Inc., Sakaiovex.

Dimensional stability, is the change of dimensions in textile products when they are washed or relaxed. The change is always expressed relative to the dimensions before the exposure of washing or relaxing. Shrinkage is also called residual shrinkage and measured in percentage. The major cause of shrinkages is the release of stresses and strains introduced in manufacturing processes. Textile manufacturing is based on the conversion of fiber into yarn, yarn into fabric, includes spinning, weaving, or knitting, etc. The fabric pass through many inevitable changes and mechanical forces during this journey. When the products are immersed in water, the water acts as a relaxing medium, and all stresses and strains get relaxed and try to come back to its original state. The dimensional stability of textile materials is an important quality parameter. Failing and unstable materials can cause deforming of the garments or products. Shrinkage is tested at various stages, but most importantly before cutting the fabric into further sewn products and after cutting and sewing prior to supplying the products to buyers and consumers. It is a required parameter of quality control to ensure the sizes of the products to avoid any complaints regarding deformation or change in dimensions after domestic Laundry. The tests are conducted with provided specifications of buyers imitating the same conditions like washing cycle time, temperature and water ratio and fabric load and sometimes top loading and front loading washing machines are chosen to authenticate the test and assurance of the results. This procedure provides standard and alternate home laundering conditions using an automatic washing machine. While the procedure includes several options, it is not possible to include every existing combination of laundering parameters. The test is applicable to all fabrics and end products suitable for home laundering.

Tailored fiber placement

Tailored fiber placement (TFP) is a textile manufacturing technique based on the principle of sewing for a continuous placement of fibrous material for composite components. The fibrous material is fixed with an upper and lower stitching thread on a base material. Compared to other textile manufacturing processes fiber material can be placed near net-shape in curvilinear patterns upon a base material in order to create stress adapted composite parts.

3D braided fabrics are fabrics in which yarn runs through the braid in all three directions, formed by inter-plaiting three orthogonal sets of yarn. The fiber architecture of three-dimensional braided fabrics provides high strength, stiffness, and structural integrity, making them suitable for a wide array of applications. 3D fabrics can be produced via weaving, knitting, and non-weaving processes.

References

  1. 1 2 3 P. Schwartz, "Structure and Mechanics of Textile Fibre Assemblies", Woodhead publishing Ltd. 2008.
  2. 1 2 F. C. Campbell, Manufacturing Processes For Advanced Composites, Oxford, UK: Elsevier, 2004.
  3. ↑ Bilisik, Kadir (2010). "Multiaxis 3D Woven Preform and Properties of Multiaxis 3D Woven and 3D Orthogonal Woven Carbon/Epoxy Composites". Journal of Plastics and Reinforced Composites. 29.8 (1173–186).
  4. ↑ De Luycker, E.; Morestin, F.; Boisse, P.; Marsal, D. (2009). "Simulation of 3D Interlock Composite Preforming" (PDF). Composite Structures. 88 (4): 615–23. doi:10.1016/j.compstruct.2008.06.005.
  5. ↑ McClain & Goering (2013). "Overview of Recent Developments in 3D Structures". Albany Engineered Composites (AEC).
  6. ↑ "3D Woven Composite Structures". Bally Ribbon Mills. Retrieved 20 July 2016.
  7. ↑ N. Khokar, "3D Fabric-forming Processes: Distinguishing between 2D-weaving, 3Dweaving and an Unspecified Non-interlacing Process," Journal of the Textile Institute, vol. 87, no. 1, pp. 97–106, 1996.
  8. ↑ M. H. Mohamed and Z.-H. Zhang, "Method of Forming Variable Cross-Sectional Shaped Three-Dimensional Fabrics". US Patent 5085252, 4 February 1992.
  9. ↑ N. Khokar, "3D-weaving: Theory and Practice," Journal of the Textile Institute, vol. 92, no. 2, pp. 193–207, 2001.
  10. ↑ N. Khokar, "Noobing: A Nonwoven 3D Fabric-forming process explained," Journal of the Textile Institute, vol. 93, no. 1, pp. 52–74, 2002.
  11. 1 2 3 M. H. Mohamed and K. K. Wetzel, "3D Woven Carbon/Glass Hybrid Spar Cap for Wind Turbine Rotor Blade," Journal of Solar Energy Engineering, vol. 128, no. November, pp. 562–573, 2006.
  12. ↑ Moutos FT, Glass KA, Compton SA, Ross AK, Gersbach CA, Guilak F, Estes BT. Anatomically shaped tissue-engineered cartilage with tunable and inducible anticytokine delivery for biological joint resurfacing. Proc Natl Acad Sci U S A. 2016;113(31):E4513-22. doi: 10.1073/pnas.1601639113.
  13. ↑ Miravete, Antonio (1999). Three-D Textile Reinforcements in Composite Materials. CRC Press.
  14. ↑ Bannister, M. (2001). "Challengers for Composites into the Next Millennium – A Reinforcement Perspective". Composite Part A. 32 (901–910).
  15. ↑ Potluri, P.; Rawal, A.; Rivaldi, M.; Porat, I. (2003). "Geometrical Modelling and Control of a Triaxial Braiding Machine for Producing 3D Preforms". Composites Part A: Applied Science and Manufacturing. 34 (6): 481–492. doi:10.1016/S1359-835X(03)00061-7.
  16. ↑ Tada, M.; Osada, T.; Nakai, A.; Hamada, H. (2000). Proceedings of 6th International SAMPE Symposium. Tokyo.
  17. ↑ Laourine, E.; Schneider, M.; Wulfhorst, B. (2000). "Production and Analysis of 3D Braided Textile Preforms for Composites". Texcomp. 5.
  18. ↑ Mouritz & Bannister (1999). "Review of Applications for Advanced Three-Dimensional Fibre Textile Composites". Composites Part A: Applied Science and Manufacturing. 30 (12): 1445–1461. doi:10.1016/S1359-835X(99)00034-2.
  19. 1 2 Tong, L.; Mouritz, A.P.; Bannister, M. (2002). 3D Fibre Reinforced Polymer Composites. Elsevier. ISBN   9780080439389.
  20. 1 2 Mouritz & Cox (2000). "A Mechanistic Approach to the Properties of Stitched Laminates". Composites 2000. 31A (1–27).
  21. ↑ Mahmood, A. Grey Systems – Theory and Application.
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