Patent Application
20170350048
The subject matter disclosed herein relates to fiber reinforced composite materials, and more particularly to composite materials having discontinuous fiber reinforcement.
Continuous fibers, such as continuous carbon fibers or continuous glass fibers, are traditionally used as reinforcement for polymer matrix composite (PMC) material. Continuous fiber tows, or rovings, are used to make either prepreg tapes (including the fiber and a matrix material such as epoxy resin) or woven into a fabric. Prepreg tapes with continuous fibers are generally not flexible enough to form components with complex shapes. Further, the mechanical performance of the uni-directional continuous fiber prepreg materials are superior to woven fabric reinforced composites due to the fiber undulation necessary to construct the woven fabric.
As an alternative to the continuous fiber construction, materials with relatively short fiber lengths are being produced. One method of such production begins with continuous fibers, which are then stretched until the continuous fibers break into shorter fibers. Such a process is costly, since it uses continuous fibers as its basis. Further, the stretch-break process is difficult to control. Other short fiber production technologies exist, but those processes result in randomly-oriented short fibers, in which the directional or anisotropic advantages of composite materials are lost.
In one embodiment, a method of forming a fiber reinforced composite material includes cutting a plurality of reinforcing fibers to a selected length, directing the plurality of reinforcing fibers through a fiber alignment mechanism, orienting the plurality of reinforcing fibers in a selected direction via the fiber alignment mechanism, and adhering the aligned plurality of reinforcing fibers to a substrate material to form the fiber reinforced composite material.
Additionally or alternatively, in this or other embodiments the fiber alignment mechanism is one of air, an ultrasonic field or an alignment blade.
Additionally or alternatively, in this or other embodiments directing the plurality of reinforcing fibers through the filter alignment mechanism includes directing the plurality of reinforcing fibers through an electrical field to orient the plurality of reinforcing fibers in the selected direction.
Additionally or alternatively, in this or other embodiments adhering the aligned plurality of reinforcing fibers to the substrate material includes adhering the aligned plurality of reinforcing fibers to a matrix material.
Additionally or alternatively, in this or other embodiments the aligned plurality of reinforcing fibers and the substrate material are directed through a consolidation roller to adhere the aligned plurality of reinforcing fibers to the substrate material.
Additionally or alternatively, in this or other embodiments the fiber reinforced composite material is collected at an output roller.
Additionally or alternatively, in this or other embodiments the plurality of fibers is a plurality of carbon fibers or glass fibers.
In another embodiment, a system for manufacturing a fiber reinforced composite material includes a feed mechanism to direct a substrate material along a selected path, a cutting mechanism to cut a plurality of reinforcing fibers to a selected length, and a fiber alignment mechanism to orient the plurality of reinforcing fibers in a selected direction before adhering the plurality of reinforcing fibers to the substrate material.
Additionally or alternatively, in this or other embodiments the fiber alignment mechanism is one of an airflow, or an ultrasonic emitter.
Additionally or alternatively, in this or other embodiments the fiber alignment mechanism includes a conductive element configured to emit an electrical field, the electrical field configured to orient the plurality of reinforcing fibers in a selected direction when the plurality of reinforcing fibers pass through the electrical field.
Additionally or alternatively, in this or other embodiments the fiber alignment mechanism includes an alignment blade to mechanically orient the plurality of reinforcing fibers in a selected direction.
Additionally or alternatively, in this or other embodiments a consolidation roller adheres the plurality of reinforcing fibers to the substrate material.
The subject matter is particularly pointed out and distinctly claimed at the conclusion of the specification. The foregoing and other features, and advantages of the present disclosure are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
The present disclosure includes continuous relatively low-cost manufacturing processes for fabricating short-fiber tapes or prepreg materials in which the short fibers are aligned in a selected direction. The processes integrate cutting to length, alignment, and impregnation of the aligned fibers into a matrix material sequentially.
Referring now to
Referring now to
The matrix film 14 is fed continuously from a feed portion, for example, a feed roller 20 to an output portion, for example, an output roller 22. While the matrix film 14 follows this path from the feed roller 20 to the output roller 22, the reinforcing fiber material 16 is fed into the manufacturing process 10 over the matrix film 14. The reinforcing fiber material 16 may be in the form of, for example, a narrow sheet, a tow or roving, or a yarn. The reinforcing fiber material 16 proceeds through a fiber cutter 24 where the reinforcing fiber material 16, and thus the reinforcing fibers 18 in the reinforcing fiber material 16, are cut to a selected fiber length.
The cut reinforcing fibers 18 are then laid on the passing matrix film 14. In some embodiments, the fiber cutter 24 is located over the matrix film 14, so the cut reinforcing fibers 18 are placed on the matrix film 14 via gravity. The matrix film 14 has a selected degree of tackiness or stickiness allowing for movement of the cut reinforcing fibers 18 on the matrix film 14 while maintaining adhesion of the cut reinforcing fibers 18 at the matrix film 14. The matrix film 14 and cut reinforcing fibers 18 proceed to a fiber orientation mechanism 26. The fiber orientation mechanism 26 acts on the cut reinforcing fibers 18 to move the cut reinforcing fibers 18 to a selected orientation, for example, orienting the cut reinforcing fibers 18 along a length 28 of the matrix film 14, or conversely, across a width of the matrix film 14. In other embodiments, the selected orientation may be not along the length 28 or across the width, but may be at an angle nonparallel to both the width and the length 28.
The fiber orientation mechanism 26 may utilize one or more technologies to move the cut reinforcing fibers 18 to the selected location as the cut reinforcing fibers 18 are placed on the matrix film 14, or after the cut reinforcing fibers 18 contact the matrix film 14. Such technologies may include, but are not limited to, a flow of air to orient the cut reinforcing fibers 18, dielectrophoresis, where the cut reinforcing fibers 18 are subjected to an uneven electrical field to orient the cut reinforcing fibers 18, or ultrasonic waves may be utilized to align the cut reinforcing fibers 18. In other embodiments, as shown in
Another embodiment of the manufacturing process is illustrated in
The oriented or aligned cut reinforcing fibers 18 proceed, in some embodiments via gravity, to the paper 32 to which the cut reinforcing fibers 18 are adhered. In some embodiments, the reinforcing fibers 18 and paper 32 then may pass through a tackifier, such as a spray tackifier 36 to further adhere the cut reinforcing fibers 18 to the paper 32, and may proceed through consolidation rollers 30. As needed, the paper 32 may proceed past the fiber cutter 24 more than once to collect additional cut reinforcing fibers 18. The paper 32 and cut reinforcing fibers 18 can then be fully impregnated with matrix material 14 resulting in the composite material 12 with discontinuous reinforcing fibers 18 with an alignment in a selected direction.
The composite material 12 with aligned, discontinuous reinforcing fibers 18 may be more readily utilized to fabricate complexly-shaped components because the discontinuity of the reinforcing fibers 18 increases flexibility of the composite material 12. Further, because of the alignment of the reinforcing fibers 18, the anisotropic or directional property features of a traditional composite material are maintained.
While the present disclosure has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the present disclosure is not limited to such disclosed embodiments. Rather, the present disclosure can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate in spirit and/or scope. Additionally, while various embodiments have been described, it is to be understood that aspects of the present disclosure may include only some of the described embodiments. Accordingly, the present disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
