The use of reinforced composite materials to produce structural components is now widespread, particularly in applications where their desirable characteristics are sought, including being light in weight, strong, tough, thermally resistant, self-supporting and adaptable to being formed and shaped.
In this regard, contour woven preforms are used to provide fiber reinforcement in resin transfer molded articles, for example fancases for jet engines. Such preforms are engineered to have a specific cross-sectional shape when they are wound onto an appropriately sized mandrel. These shapes can generally be described as a variable thickness barrel section with an integral flange at either end.
Typically, such preforms consist of fabrics which are woven from materials such as glass, carbon, ceramic, aramid, polyethylene, and/or other materials which exhibit desired physical, thermal, chemical and/or other properties, chief among which is great strength against stress failure. Through the use of such fabrics, which ultimately become a constituent element of the completed composite article, the composite preform imparts the desired characteristics of the fabrics, such as very high strength, into the completed composite article. Usually particular attention is paid to ensure the optimum utilization of the properties for which the fabrics have been selected.
After the desired preform has been constructed, a molding or densifying operation takes place where a resin matrix material may be introduced to and into the woven preform, so that typically the preform becomes encased in the resin matrix material that fills the interstitial areas between the constituent elements of the preform. The resin matrix material may be any of a wide variety of materials, such as epoxy, phenolic, polyester, vinyl-ester, ceramic, carbon and/or other materials, which also exhibit desired physical, thermal, chemical and/or other properties. The materials chosen for use as the resin matrix may or may not be the same as that of the reinforcement preform and may or may not have comparable physical, chemical, thermal or other properties. Typically, however, they will not be of the same materials or have comparable physical, chemical, thermal or other properties, since a usual objective sought in using composites in the first place is to achieve a combination of characteristics in the finished product that is not attainable through the use of one constituent material alone. So combined, the woven preform and the matrix material may then be cured and stabilized in the same operation by thermosetting or other known methods, and then subjected to other operations toward producing the desired component. It is significant to note at this point that after being so cured, the then solidified mass of the matrix material normally is very strongly adhered to the reinforcing material (e.g., the woven preform). As a result, stress on the finished component, particularly via its matrix material acting as an adhesive between fibers, may be effectively transferred to and borne by the constituent material of the preform.
Fancases for jet engines, such as the example shown in FIG. 1, using contour woven preforms that provide fiber reinforcement, and then impregnated for example by resin transfer molding, are already known in the art. Use of this type of preform offers several advantages, some of which are: provide continuous fiber in the circumferential and axial directions; minimize touch labor through the elimination of cutting and darting; and minimize process waste by eliminating the need for cutting and darting.