Patent Application
20090136734
The disclosure relates to panels used for material characterization testing. More particularly, the disclosure relates to unidirectional resin infused panels having sections which may lack secondary fill-binding material and are suitable for material property characterization testing.
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 material 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, unidirectional resin infused panels 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 resin infused panel. An illustrative embodiment of the unidirectional resin infused panel includes a plurality of laminated plies of a unidirectional reinforcing fiber material each comprising a plurality of unidirectional reinforcing fibers. An unbound section is provided along the reinforcing fibers and generally free from fill-binding material. A first bound section having a fill-binding material is provided along the reinforcing fibers on a first side of the unbound section. A second bound section having a fill-binding material is provided along the reinforcing fibers on a second side of the unbound section. A cured resin is infused in the plurality of laminated plies of a unidirectional fiber material.
The disclosure is further generally directed to a method of fabricating a unidirectional resin infused panel. An illustrative embodiment of the method includes providing a plurality of plies of dry unidirectional fiber material each including a plurality of unidirectional reinforcing fibers and first and second bound sections having a fill-binding material and an unbound section generally lacking the fill-binding material between the first and second bound sections; stacking the plurality of plies of dry unidirectional fiber material; infusing the plurality of plies of dry unidirectional fiber material with resin; and curing the resin.
The disclosure is further generally directed to a method of creating test specimens from a unidirectional resin infused panel. An illustrative embodiment of the method includes providing a unidirectional resin infused panel including first and second bound sections having a fill-binding material and an unbound section between the first and second bound sections and generally lacking the fill-binding material; identifying individual sections of the unidirectional resin infused panel to be tested; and cutting the unidirectional resin infused panel between the sections.
The disclosure is generally directed to unidirectional resin infused panels which are suitable for creating test specimens for material property characterization testing using such mechanical property prediction methods as Strain Invariant Failure Theory (SIFT), for example and without limitation. The unidirectional resin infused panels may be collated from multiple lengths of dry unidirectional fiber material including bound sections having fill-binding material and unbound sections which lack fill-binding material and extend between or alternate with the bound sections. Test specimens may subsequently be cut from the unbound sections of the panels for material characterization testing.
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Each ply of 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 completely lack the fill-binding material 5. The bound sections 3 at respective ends of each unbound section 4 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.
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 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.
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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.
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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.
