Abstract: Embodiments of the presently disclosed system include a thin thermoplastic or thermosetting polymer film loaded with non-polymeric inclusions that are susceptible to heating under a time-varying magnetic field. Insertion of this additional heating layer into a structural or semi-structural heterogeneous laminate provides an “on-demand” de-bonding site for laminate deconstruction. For example, in some embodiments when the heating layer is inserted between a cured Carbon-Fiber Reinforced Plastic (CFRP) layer and a Polymeric/Metallic film stackup layer, the heating layer can be selectively heated above its softening point (e.g., by using energy absorbed from a locally-applied time-varying magnetic field) to allow for ease of applique separation from the CFRP layer.

Abstract: Edge seals for composite structure fuel tanks are disclosed herein. One disclosed apparatus includes a seal covering an exposed edge of a carbon fiber reinforced composite fuel tank, where the seal comprises a layer of dielectric material to insulate carbon fibers at the exposed edge from fuel in the tank.

Abstract: Embodiments of the presently disclosed system include a thin thermoplastic or thermosetting polymer film loaded with non-polymeric inclusions that are susceptible to heating under a time-varying magnetic field. Insertion of this additional heating layer into a structural or semi-structural heterogeneous laminate provides an “on-demand” de-bonding site for laminate deconstruction. For example, in some embodiments when the heating layer is inserted between a cured Carbon-Fiber Reinforced Plastic (CFRP) layer and a Polymeric/Metallic film stackup layer, the heating layer can be selectively heated above its softening point (e.g., by using energy absorbed from a locally-applied time-varying magnetic field) to allow for ease of applique separation from the CFRP layer.

Abstract: Edge seals for composite structure fuel tanks are disclosed herein. One disclosed apparatus includes a seal covering an exposed edge of a carbon fiber reinforced composite fuel tank, where the seal comprises a layer of dielectric material to insulate carbon fibers at the exposed edge from fuel in the tank.

Abstract: Embodiments of the presently disclosed system include a thin thermoplastic or thermosetting polymer film loaded with non-polymeric inclusions that are susceptible to heating under a time-varying magnetic field. Insertion of this additional heating layer into a structural or semi-structural heterogeneous laminate provides an “on-demand” de-bonding site for laminate deconstruction. For example, in some embodiments when the heating layer is inserted between a cured Carbon-Fiber Reinforced Plastic (CFRP) layer and a Polymeric/Metallic film stackup layer, the heating layer can be selectively heated above its softening point (e.g., by using energy absorbed from a locally-applied time-varying magnetic field) to allow for ease of applique separation from the CFRP layer.

Abstract: The cut laminate edges of aircraft fuel tanks formed of carbon fiber reinforced polymers are sealed to prevent the exposure of carbon fibers to combustible fuel. The edge seal is produced from a prepreg form using a thermosetting resin matched to the characteristics of the resin used in the laminate. The prepreg form can be applied to the cut laminate edges either before or after the laminate is cured. The edge seal acts as a dielectric layer that both electrically insulates the cut laminate edges from the fuel and mechanically contains energetic particles produced at the edges due to lightning strikes or other sources of electrical charges.

Abstract: A method for reworking an electrically conductive layer of a composite skin is disclosed in which a patch replaces the altered section of the electrically conductive layer. The method is performed by removing a portion of the electrically conductive layer to reveal the underlying composite skin. A patch is formed, having an electrically conductive section coupled to an adhesive having a low dielectric breakdown strength, and is then introduced over the underlying composite skin such that the adhesive layer covers the underlying composite skin and overlaps an unremoved portion of the electrically conductive layer. The patch is applied such that the electrically conductive section within the patch covers the adhesive layer and overlaps the unremoved section of the electrically conductive layer. The adhesive layer preferably has a low dielectric breakdown strength, so that electricity from lightning which strikes the composite skin may be conducted through the adhesive.

Abstract: A method for reworking an electrically conductive layer of a composite skin is disclosed in which a patch replaces the altered section of the electrically conductive layer. The method is performed by removing a portion of the electrically conductive layer to reveal the underlying composite skin. A patch is formed, having an electrically conductive section coupled to an adhesive having a low dielectric breakdown strength, and is then introduced over the underlying composite skin such that the adhesive layer covers the underlying composite skin and overlaps an unremoved portion of the electrically conductive layer. The patch is applied such that the electrically conductive section within the patch covers the adhesive layer and overlaps the unremoved section of the electrically conductive layer. The adhesive layer preferably has a low dielectric breakdown strength, so that electricity from lightning which strikes the composite skin may be conducted through the adhesive.

Abstract: A method for reworking an electrically conductive layer of a composite skin is disclosed in which a patch replaces the altered section of the electrically conductive layer. The method is performed by removing a portion of the electrically conductive layer to reveal the underlying composite skin. A patch is formed, having an electrically conductive section coupled to an adhesive having a low dielectric breakdown strength, and is then introduced over the underlying composite skin such that the adhesive layer covers the underlying composite skin and overlaps an unremoved portion of the electrically conductive layer. The patch is applied such that the electrically conductive section within the patch covers the adhesive layer and overlaps the unremoved section of the electrically conductive layer. The adhesive layer preferably has a low dielectric breakdown strength, so that electricity from lightning which strikes the composite skin may be conducted through the adhesive.

Abstract: A fastening assembly for a composite structure including a washer sealing the assembly for internal lightning strike protection. The washer includes one or more concentric ribs that are dielectric rings on both sides. When used (e.g., with a nut and bolt) internal to a structure, especially a composite structure, the washer seals the fastener hole (i.e., that the bolt passes through) and contains any sparking and hot gasses that may arise in the fastener hole from entering the structure.

Abstract: A fastening assembly for a composite structure including a washer sealing the assembly for internal lightning strike protection. The washer includes one or more concentric ribs that are dielectric rings on both sides. When used (e.g., with a nut and bolt) internal to a structure, especially a composite structure, the washer seals the fastener hole (i.e., that the bolt passes through) and contains any sparking and hot gasses that may arise in the fastener hole from entering the structure.

Abstract: A washer, a fastening assembly including the washer and a composite structure including the washer sealing the assembly for internal lightning strike protection. The washer includes one or more concentric ribs that are dielectric rings on both sides. When used (e.g., with a nut and bolt) internal to a structure, especially a composite structure, the washer seals the fastener hole (i.e., that the bolt passes through) and contains any sparking and hot gasses that may arise in the fastener hole from entering the structure.

Abstract: A method for reworking an electrically conductive layer of a composite skin is disclosed in which a patch replaces the altered section of the electrically conductive layer. The method is performed by removing a portion of the electrically conductive layer to reveal the underlying composite skin. A patch is formed, having an electrically conductive section coupled to an adhesive having a low dielectric breakdown strength, and is then introduced over the underlying composite skin such that the adhesive layer covers the underlying composite skin and overlaps an unremoved portion of the electrically conductive layer. The patch is applied such that the electrically conductive section within the patch covers the adhesive layer and overlaps the unremoved section of the electrically conductive layer. The adhesive layer preferably has a low dielectric breakdown strength, so that electricity from lightning which strikes the composite skin may be conducted through the adhesive.

Abstract: A method for reestablishing the electrical continuity of an electrically conductive layer of a composite aircraft wing damaged by a lightning strike or other mechanical event is disclosed in which a copper patch replaced the damaged section of the electrically conductive layer contained. The repair is performed by first removing any surfacers, fasteners, and damaged electrically conductive layer to expose a portion of the underlying composite skin. A copper patch having a copper foil section coupled to an unsupported film adhesive is then introduced onto an underlying composite skin opening contained within an undamaged section of a copper foil grid and covered with resin-impregnated fiberglass material. The film adhesive and resin-impregnated fiberglass material are then cured and fasteners are then reinserted within the fiberglass material, copper patch and underlying composite skin. The surface of the composite wing is then reprimed and repainted to complete the repair.

Abstract: An apparatus, system, and method for lightning strike protection and verification are provided. In one embodiment, the apparatus includes at least one fastener extending through both the structure and substructure to secure the structure and substructure together. The apparatus also includes an insert disposed between the substructure and at least a portion of the fastener, where the insert includes dielectric and magnetizable material such that the insert is capable of reducing the incidence of sparking between at least one component associated with the fastener and the substructure.

Abstract: A method and apparatus for simultaneously measuring current flows through fasteners in a multi-structure composite joint is provided. The method comprising inserting a printed circuit board between at least two structures, the printed circuit board being etched with at least one Rogowski coil sensory circuit the at least two structures being joined with at least one fastener extending through the at least one Rogowski coil sensory circuit in the printed circuit board; detecting current in the at least one fastener; transmitting the detected current from each fastener to a corresponding passive integrator circuit for capturing transient pulses and integrating the pulses into an output; and transmitting the output to a processing unit.

Abstract: The cut laminate edges of aircraft fuel tanks formed of carbon fiber reinforced polymers are sealed to prevent the exposure of carbon fibers to combustible fuel. The edge seal is produced from a prepreg form using a thermosetting resin matched to the characteristics of the resin used in the laminate. The prepreg form can be applied to the cut laminate edges either before or after the laminate is cured. The edge seal acts a dielectric layer that both electrically insulates the cut laminate edges from the fuel and mechanically contains energetic particles produced at the edges due to lighting strikes or other sources of electrical charges.

Abstract: A method and apparatus for simultaneously measuring current flows through individual structures in a multi-structure composite joint is provided. The method comprising inserting a printed circuit board, etched with Rogowski coil sensory circuits, inside the joint between at least two structures with the at least two structures extending through the Rogowski coil sensory circuits in the printed circuit board; detecting induced current in the at least two fasteners; transmitting the induced current to a passive integrator array for capturing transient pulses from the printed circuit board and integrating the pulses into an array output; transmitting the array output to a processing unit.

Abstract: A method and tooling concept for fabricating complex composite parts is provided. The method and tooling concept use various tooling configurations in order to produce varying magnitudes of thermal expansion at different areas within the tooling concept. The varying magnitudes of thermal expansion allow the tool concept to account for varying magnitudes of tool movement needed to debulk and consolidate varying thickness areas of the composite workpiece being cured. The tooling concept is formed of different materials having different thicknesses that allow the tooling concept to produce varying magnitudes of thermal expansion. The exterior surface of the tooling concept is covered by a compliant covering. The compliant covering helps to equalize the consolidation pressures produced by the tooling concept during curing. A composite wing box structure fabricated using the method and tooling concept is also disclosed.

Abstract: An method and tooling concept for fabricating complex composite parts is provided. The method and tooling concept use various tooling configurations in order to produce varying magnitudes of thermal expansion at different areas within the tooling concept. The varying magnitudes of thermal expansion allow the tool concept to account for varying magnitudes of tool movement needed to debulk and consolidate varying thickness areas of the composite workpiece being cured. The tooling concept is formed of different materials having different thicknesses that allow the tooling concept to produce varying magnitudes of thermal expansion. The exterior surface of the tooling concept is covered by a compliant covering. The compliant covering helps to equalize the consolidation pressures produced by the tooling concept during curing. A composite wing box structure fabricated using the method and tooling concept is also disclosed.