Lockheed Martin Corporation

Lockheed Fort Worth Company

Elbert Lee McKague, Jr

Ronald P Schmidt

David Uhl

James R Albritton

John Edward Phillips

Ronald Kendall Cox

A preformed component or &ldquo;preform&rdquo; for a structural member has a planar base with two longitudinal legs extending in parallel from the base. A channel is defined between the legs for insertion of a flat plate that forms the first member of the structural member. The base of the preform is bonded to a composite panel. The preform is a composite material having continuous filaments of woven or braided fiber. The preform is impregnated with a thermoset resin that bonds the first member to the second member of the structural member. The preform may have filaments in the legs having a coefficient of expansion to match the plate, and filaments in the base having a coefficient of expansion to match the panel.

Apparatus and method for joining dissimilar materials to form a structural support member

An uncured, thermoset resin sheet is reinforced with oriented fibers and is slit to define a desired length for the fibers. A series of the sheets are cut and stacked to form integrated layers of the composite material for a structural panel. The panel has two outer layers that sandwich two shorter layers on each end, and syntactic or foamed resin layer in between. Each of the composite layers is formed from the same materials and by the same process, but may vary in the directional orientation of their fibers. The uncured panel is assembled into a flexible, substantially flat configuration is heated and formed to the contours of a tool having a undulated surface geometry. The panel is further heated to cure the combined composite and syntactic resins into a series of undulations that permeate each of its layers. In one embodiment, the undulations are in a smooth, sine wave-like pattern that allow the panel to maintain a planar configuration. Although the fibers themselves do not stretch, the short lengths of the fibers enable stretching of the material in the fiber direction so that deformation of the composite is possible in all directions. The panel is stiffened both by spacing its outer layers apart with the syntactic layer, and by its undulated surface.

Composite structural panel with undulated body

A support structure flange preform resembles the Greek letter &ldquo;pi&rdquo; and has a base with two legs extending therefrom. The preform is composed of a composite material that is formed from tows of woven or braided fiber. The tows are oriented to extend throughout each the base and legs. The preform may be either impregnated with a suitable thermoset resin, or may be unimpregnated so that resin may be infused at a later step of the overall manufacturing process. Two of the preforms are joined to a sine wave-shaped web of the structural beam. The web is formed from uncured, thermoset resin sheets that are reinforced with oriented fibers. The web has two outer laminates that sandwich a syntactic or foamed resin layer in between. The legs of each preform straddle one edge of the web and are shaped to both sides to the precise contours of the web. A laminate strip is positioned against the base of each preform to create a pair of flanges for the structural support member. The assembled structure is then heated and cured. The web and/or flanges of the structure also may be configured with alternating beads, tapered in either the vertical or horizontal direction, or inclined at non-orthogonal angles.

Composite material support structures with sinusoidal webs and method of fabricating same

Slits of precisely controlled length are cut in a layer of material having collimated fibers. Each slit begins at a defined coordinate point and proceeds diagonally at an acute angle relative to the axial direction of the fibers. Subsequent slits are initiated at coordinate points relative to the starting coordinate point of the previous slit. The region of fibers located above and below each slit are referred to as upper and lower fiber bands, respectively. The lower bands are substantially aligned in a zonal band that runs perpendicular to the lengths of the fibers. The location of the beginning coordinate point for each slit defining a zonal band is defined by adding a random length dimension to a previous starting coordinate point. The maximum length of the cut fibers may be determined in accordance with the intended application and process. For example, in the case of a corrugated shape that is made by forming a flat laminate into the final corrugated shape in one step, the maximum fiber length is limited to a dimension somewhat less than the period of the corrugations. The minimum length of the fibers is selected to assure maximum load-carrying capacity of the finished composite component.

Method of shaping continuous fiber lamina to an undulated surface by cutting individual fibers

A preformed component or &ldquo;preform&rdquo; for a structural member has a planar base with two longitudinal legs extending in parallel from the base. A channel is defined between the legs for insertion of a flat panel that forms the web of the structural member. The preform is a composite material having continuous filaments of woven or braided fiber. The preform is impregnated with a thermoset resin that bonds the web to the flange of the structural member. The preform provides excellent structural support even if the web and the flange are formed from dissimilar materials such as metallic and composite. The resin is structurally reinforced with oriented fibers in such a manner as to provide coupling strength between the joined members.

A method for fabricating a composite part (42) from a plurality of composite layers (14) is provided. The method includes laying-up the composite layers (26) one upon another to form a collection of layers in a configuration and debulking the configuration of layers (26) by applying pressure sufficient to reduce the thickness of the layers to within approximately twenty percent (20%) of the part's final thickness. The debulked layers (28) may then be stored, generally at room temperature. To later form the part, the debulked layers (28) are heated to a temperature above their glass transition temperature and formed into the part's final shape. Heat may then be continuously applied to the layers while holding them in the part's final shape with sufficient force to achieve and maintain the part's thickness and density and until the heating causes the layers to become sufficiently cured so that the part's shape, thickness, and density are maintained.

Method and system for fabricating parts from composite materials

A composite structural member having an improved joint for securing loads thereto is formed from a body of composite sheet material. A loading member having an outer periphery and being configured to secure loads thereto is provided with an undercut portion or recess located along the outer periphery. The composite sheet material overlays the loading member about the outer periphery and has a lip formed from the sheet material which projects into and engages the undercut portion of the outer periphery. A retaining tension band is wrapped around the outer periphery of the loading member and the lip and maintains the lip in engagement with the undercut portion of the loading member so that the loading member is securely held in place relative to the sheet material when loads are applied to the loading member.

Growing community of inventors

Fort Worth, TX, United States of America

Elbert Lee McKague, Jr