Patent Application
20080008898
So that the manner in which the features and advantages of the present invention, which will become apparent, are attained and can be understood in more detail, a more specific description of the invention briefly summarized above may be had by reference to the embodiments thereof that are illustrated in the appended drawings which form a part of this specification. It is to be noted, however, that the drawings illustrate only some embodiments of the invention and therefore are not to be considered limiting of its scope as the invention may admit to other equally effective embodiments.
a and 3b are highly magnified metallurgical sectional views of the structural joint of
Referring to
As shown in
Since the preform 13 is formed from flexible metallic fibers, the preform 13 conforms to a shape of the first and second components 21, 25. The braze 23 may comprise a high temperature braze metal alloy that forms a matrix for the wire and to join the woven preform 13 to the skin 21 and the frame 25. The braze 23 may be selected from commercially available braze alloys and form depending upon joint material selection and design. Braze 23 may further comprise a braze alloy in the form of a powder, tape, and braze foil.
The edges of the preform 13 are tapered to a feather edge to avoid stress concentrations and stiffness mismatch. The fiber used to form the preform 13 may be formed from a metal such as stainless steel alloys, titanium alloys, nickel-based alloys, etc. However, still other materials, such as copper, also may be used. In one embodiment, the fibers have a diameter in a range of a few microns to 0.010 inches. Depending on the temperature and other conditions, parameters, etc., used to form the structural joint 11, the fibers of the preform 13 and the braze 23 may remain separate and distinct materials in a connector or structural joint, or, alternatively, both the fibers of the preform 13 and the braze 23 may be diffused into each other to form a homogenous metal alloy connector.
Referring now to
The method also may comprise joining the preform and the first and second components together without structural fasteners, and providing the first component as a structural skin, and the second component as a flangeless frame. In addition, one embodiment of the structural joint may be formed in a vacuum or inert atmosphere. After steps 113 and 115, the fibers and braze may remain substantially separate and distinct materials, or, when held at temperature, completely diffuse to form a single homogenous material. Furthermore, common industry practices, such as resistance tack welding, may be used to initially maintain the position of the components before heating.
The present invention has many advantages. The use of metallic fibers in a three-dimensional woven preform with a brazing process creates a metallic structural joint capable of withstanding high temperature environments. Joining applications include honeycomb core panels, sine wave spars, beaded hat stiffeners to skins, and other web-to-flange type structural joints that require reduced weight and metallic structure. The preforms may be used as thermal protection liners, strain isolation layers, or actual structural shapes of brazed metallic fiber woven preforms. The present invention also may be adapted for many applications by fiber orientation to reduce or distribute load. The elimination or reduction in fastener requirements also reduces weight, and facilitates joining complex contoured structures. Furthermore, the metal fiber and braze connector has inherent fatigue resistance since the dissimilar materials provide no homogenous grain structure along which cracks may propagate.
While the invention has been shown or described in only some of its forms, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes without departing from the scope of the invention.
