The disclosure relates to dry unidirectional fiber material which is suitable for a resin infusion process and suitable for material property characterization testing. More particularly, the disclosure relates to a dry unidirectional fiber material and a method of fabricating a dry unidirectional fiber material having bound sections which include fill-binding material and unbound sections which lack fill-binding material and alternate with the bound sections.
In the fabrication of composite materials, it may be necessary to utilize testing methods for material characterization such as to determine mechanical properties of the fabricated materials using Strain Invariant Failure Theory (SIFT) and/or other mechanical property prediction methods. Unidirectional fiber which is used for material characterization testing may include fill-binding materials such as fill direction yarns, veils or thermofused filaments, for example and without limitation. These secondary fill-binding materials may impact basic physical material parameters such as fiber volume and resin density and may adversely affect the tensile, compression and shear test results for determination of strength, modulus and strain invariant properties. Therefore, a unidirectional fiber material having sections or zones which lack secondary fill-binding materials may be useful for material characterization analysis in implementation of mechanical property prediction methods such as SIFT.
The disclosure is generally directed to a unidirectional fiber material. An illustrative embodiment of the unidirectional fiber material includes a plurality of unidirectional reinforcing fibers, an unbound section provided along the reinforcing fibers and generally free from fill-binding material, a first bound section having a fill-binding material provided along the reinforcing fibers on a first side of the unbound section and a second bound section having a fill-binding material provided along the reinforcing fibers on a second side of the unbound section.
The disclosure is further generally directed to a method of fabricating a unidirectional fiber material. An illustrative embodiment of the method includes providing a plurality of reinforcing fibers, orienting the reinforcing fibers in generally parallel relationship with respect to each other, applying a fill-binding material to a first length of the reinforcing fibers, applying a fill-binding material to a second length of the reinforcing fibers and leaving a third length of the reinforcing fibers between the first length of the reinforcing fibers and the second length of the reinforcing fibers free from a fill-binding material.
The disclosure is generally directed to a dry unidirectional fiber material and fabrication of a dry unidirectional fiber material which is suitable for a resin infusion liquid molding process compatible with material property characterization testing using such mechanical property prediction methods such as Strain Invariant Failure Theory (SIFT), for example and without limitation. The dry unidirectional fiber material may include bound sections having fill-binding material and unbound sections which lack fill-binding material and alternate with the bound sections. The fabricated dry unidirectional fiber material may subsequently be subjected to a resin infusion liquid molding process to form a test composite material. The unbound sections which are free of the fill-binding material in the composite may define test zones for extraction of material characterization test specimens.
Referring initially to
The unidirectional fiber material 1 may include a pair of bound sections 3 and at least one unbound section 4 between the bound sections 3. A fill-binding material 5 may be provided in each bound section 3. The fill-binding material 5 may be glass fiber, thermofusable yarn, fill direction yarn, veils, stitches and/or any other suitable fill binder. The fill-binding material 5 may be oriented in generally perpendicular relationship with respect to the unidirectional reinforcing fibers 2. Each unbound section 4 may partially or completely lack the fill-binding material 5. The bound sections 3 may facilitate handling of the unidirectional fiber material 1.
In some embodiments, the unidirectional fiber material 1 may include multiple bound sections 3 and multiple bound sections 4. The bound sections 3 may be disposed in spaced-apart relationship with respect to each other along the longitudinal axis 8 of the unidirectional fiber material 1. The unbound sections 4 may be disposed in spaced-apart relationship with respect to each other along the longitudinal axis 8 of the unidirectional fiber material 1 and may alternate with the bound sections 3. Therefore, each unbound section 4 may be flanked by a pair of bound sections 3. In the illustrative embodiment of the unidirectional fiber material 1 which is shown in
The unidirectional fiber material 1 may be fabricated using any suitable technique which is known by those skilled in the art. In some fabrication methods, the unidirectional fiber material 1 may be fabricated on a conventional weaving loom (not shown) using fiber tows and spacing of the unidirectional fibers 2 which will provide the desired areal weight of the unidirectional fiber material 1. The unidirectional fibers 2 may be woven with the fill-binding material 5 across the full width of the unidirectional fibers 2 for the required length stabilization during panel molding along the longitudinal axis of the unidirectional fibers 2. The resulting fabric material may then be run through the weaving loom with no fill-binding material 5 for the length required for mechanical testing [PEG1] along the longitudinal axis of the unidirectional fibers 2. This sequence of alternating bound sections or zones with the fill-binding material 5 and unbound sections or zones without the fill-binding material 5 may be repeated any desired number of times to fabricate a selected yardage of the unidirectional fiber material 1 for use in test specimens, for example and without limitation. The fabrication process may be accomplished through the use of manual or pre-programmed means that stop and restart the fill-binding material 5 as required.
Referring next to
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Each of the processes of method 78 may be performed or carried out by a system integrator, a third party, and/or an operator (e.g., a customer). For the purposes of this description, a system integrator may include without limitation any number of aircraft manufacturers and major-system subcontractors; a third party may include without limitation any number of vendors, subcontractors, and suppliers; and an operator may be an airline, leasing company, military entity, service organization, and so on.
As shown in
The apparatus embodied herein may be employed during any one or more of the stages of the production and service method 78. For example, components or subassemblies corresponding to production process 84 may be fabricated or manufactured in a manner similar to components or subassemblies produced while the aircraft 94 is in service. Also, one or more apparatus embodiments may be utilized during the production stages 84 and 86, for example, by substantially expediting assembly of or reducing the cost of an aircraft 94. Similarly, one or more apparatus embodiments may be utilized while the aircraft 94 is in service, for example and without limitation, to maintenance and service 92.
Although the embodiments of this disclosure have been described with respect to certain exemplary embodiments, it is to be understood that the specific embodiments are for purposes of illustration and not limitation, as other variations will occur to those of skill in the art.