Patent Application
20120318448
The present invention generally involves a method for manufacturing a composite surface. Particular embodiments of the present invention may produce a laminated ply assembly having an interrupted ceramic surface profile.
Ceramic matrix composites are commonly used in high temperature applications because of their low weight and high heat resistance. Shrouds for gas turbine engines include mounting features to engage with adjacent support structures to retain the shroud segment. Mounting features between ceramic matrix composites and metal structures include an engagement tolerance within the retaining features to permit differing thermal growths between the shroud segments and the support structure. The shrouds are often made from or coated with a ceramic matrix composite that is lighter than superalloys and can also withstand the high temperature environment associated with a hot gas path. The tolerance in the attachment of the shroud to the outer case may result in undesirable movement or vibration of the shroud. As a result, a mechanical damper may be placed against the shroud to reduce or prevent vibration of the shroud. The mechanical damper, often made from but not limited to metals, acts as a mass against the shroud, and the resulting friction between the mechanical damper and the shroud reduces or prevents relative motion of the shroud.
Over time, the continuous contact between the ceramic material in the shroud and the mechanical damper may have an abrasive effect on the mechanical damper. Specifically, temperature changes, pressure changes, vibrations, and other dynamic forces may cause the ceramic material to abrade or erode the adjacent metal surfaces of the mechanical damper. The abrasion or erosion of the mechanical damper reduces the effectiveness of the mechanical damper, requiring increased maintenance and inspections to avoid premature failure and/or unanticipated outages.
Reducing the surface area of the ceramic material in contact with the mechanical damper is one method to reduce the erosive wear on the mechanical damper. For example, prior attempts to reduce the surface area of the ceramic material in contact with the mechanical damper have focused on post-fabrication removal of local areas in the ceramic surface and/or the application of a wear inhibiting material to the ceramic component and/or mechanical damper. However, the post-fabrication removal of ceramic material in a localized area is difficult to accomplish. For example, portions of the ceramic component may be inaccessible to post-fabrication machining, and inadvertent excessive removal of the ceramic material may damage the component, resulting in additional costly repairs. The application of a wear inhibiting material, as in a coating form, may be complicated by the ability to successfully bond the wear inhibiting material to the ceramic component and/or mechanical damper. Once bonded, the wear inhibiting material will be under extended distress due to cyclic loading of the contact pressure between the ceramic component and the mechanical damper, and the high temperatures associated with the hot gas path may break down the bond strength, resulting in a limited life of the bond.
Therefore, an improved method for manufacturing a composite surface that reduces wear between the ceramic materials and mating metallic surfaces would be useful.
Aspects and advantages of the invention are set forth below in the following description, or may be obvious from the description, or may be learned through practice of the invention.
One embodiment of the present invention is a method for manufacturing a composite. The method includes perforating an outer ply to create perforations through the outer ply and inserting a filler material into the perforations. The method further includes laminating the outer ply to an inner ply.
In another embodiment, a method for manufacturing a composite includes forming an outer composite ply and removing portions from the outer composite ply to create perforations through the outer composite ply. The method further includes filling at least a portion of the perforations in the outer composite ply with a filler material and laminating the outer composite ply to an inner ply.
In yet another embodiment, a method for manufacturing a composite includes forming an outer ply, removing portions from the outer ply to create an interrupted surface on the outer ply, and applying a filler material to the interrupted surface. The method further includes laminating the outer ply to an inner ply.
Those of ordinary skill in the art will better appreciate the features and aspects of such embodiments, and others, upon review of the specification.
A full and enabling disclosure of the present invention, including the best mode thereof to one skilled in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which:
Reference will now be made in detail to present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention.
Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope or spirit thereof For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.
Various embodiments of the present invention include methods for manufacturing a composite material having a localized interrupted surface on an outer surface of the composite. In particular embodiments, multiple layers or plies of ceramic, metal, and/or organic matrix composites may be laminated together with the localized interrupted surface on the outer surface of the laminate. As a result, the method produces the desired interrupted surface without requiring post-fabrication machining or other processing to achieve the desired surface characteristics.
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The method of manufacture described herein thus provides several technical and commercial advantages over existing post-fabrication machining techniques. For example, the removal of the portions 16 from the single ply 10 prior to formation of the system component allows unrestricted access to the entire surface area of the single ply 10 to permit precise positioning of the interrupted surface 12 at the desired location without risking accidental damage to the inner plies 28 of the system component. In addition, the precise placement of the interrupted surface 12 is not limited by the final shape, location, or accessibility of the system component.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other and examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
