Abstract: A system for repair of damaged holes in composite structures incorporates a repair system tool device having a sleeve sized to be closely received in a hole in a composite structure. The sleeve has a central bore for receiving parent resin and an array of orifices for radial expulsion of the parent resin into the hole. A caul plate seals the central bore and a vacuum bag covering the caul plate is sealed to the surface of the composite structure. Introduction of vacuum in the vacuum bag provides a differential pressure for infusion of resin from the orifices in the sleeve into delaminations extending from the hole.

Abstract: There is provided a high temperature hybridized molecular functional group adhesion barrier coating for a composite structure. The coating has one or more hybridized molecular functional groups attached to a composite surface of the composite structure, wherein the one or more hybridized molecular functional groups are hybridized through a chemical derivatization process. The coating further has one or more chemical derivatization compounds attached to the one or more hybridized molecular functional groups via a condensation reaction. The coating is resistant to high heat temperatures in a range of from about 350 degrees Fahrenheit to about 2000 degrees Fahrenheit, and the coating is a thermally protective, toughened adhesion coating that mitigates effects of a hostile operating environment.

Abstract: Disclosed are systems and methods of creating altered adhesive bonded joints between metal or composite substrates, including bonds that are weaker in strength than selected reference bonds. One method of creating an altered adhesive bond includes providing a first substrate and a second substrate, selecting a manufacturing process having a plurality of steps designed to produce a desired, or reference, adhesive bond having a desired strength, and selectively altering at least one of the plurality of steps during performance of the manufacturing process to produce an altered bond between the first substrate and the second substrate, the altered bond having an altered strength that is weaker than the strength of the desired adhesive bond. The systems may include systems that may be utilized to create the altered adhesive bonds and/or test standards.

Abstract: Apparatus and methods to determine structural integrity of composites are described herein. One described example method for determining sufficiency of structural integration of a composite structure for an aircraft includes applying a fluid droplet to a surface of the composite structure, determining a three-dimensional contact angle between the surface and a portion of the droplet, comparing the three-dimensional contact angle to a threshold angle, and determining whether the structural integration of the composite structure is sufficient based on the comparison.

Abstract: There is provided a high temperature hybridized molecular functional group adhesion barrier coating for a composite structure. The coating has one or more hybridized molecular functional groups attached to a composite surface of the composite structure, wherein the one or more hybridized molecular functional groups are hybridized through a chemical derivatization process. The coating further has one or more chemical derivatization compounds attached to the one or more hybridized molecular functional groups via a condensation reaction. The coating is resistant to high heat temperatures in a range of from about 350 degrees Fahrenheit to about 2000 degrees Fahrenheit, and the coating is a thermally protective, toughened adhesion coating that mitigates effects of a hostile operating environment.

Abstract: A method and apparatus comprising a composite section. The composite section has a cylindrical shape. The composite section also has an outer wall configured to be bonded to a first inner wall of a first composite cylindrical fuselage section and a second inner wall of a second composite cylindrical fuselage section for an aircraft.

Abstract: The disclosure provides in one embodiment a method of applying a high temperature hybridized molecular functional group adhesion barrier coating to a surface of a structure. The method includes providing a structure having at least one surface to be bonded, preparing the at least one surface to expose active reactive surface sites, providing one or more liquid or solid phase chemical derivatization compounds, applying heat to the one or more liquid or solid phase chemical derivatization compounds to vaporize the one or more liquid or solid chemical derivatization compounds, depositing the one or more vaporized chemical derivatization compounds on the prepared surface to form a derivatized composite surface having hybridized molecular functional groups, and heat curing the derivatized composite surface to form a high temperature hybridized molecular functional group adhesion barrier coating.

Abstract: A patch for a structure has a rework area with an inconsistency formed therein. The patch comprises a patch body having at least two regions including a fail-safe region and a safe-life region encompassing the fail-safe region. The safe-life region has a mode I interlaminar fracture toughness that is less than the mode I interlaminar fracture toughness of the fail-safe region.

Abstract: A unitized composite aircraft wing includes upper and lower composite laminate wing skins that have differing stiffnesses and are bonded to a composite grid structure. The grid structure includes grid spars extending in a span-wise direction, and cross beams extending in a chord-wise direction of the wing. The grid spars include caps bonded to the upper and lower wing skins.

Abstract: A patch for reworking an inconsistent area in a composite structure includes a composite laminate patch and a layer of adhesive for bonding the laminate patch to the composite structure. The laminate patch has at least first and second regions for releasing strain energy around the inconsistent area respectively at different rates.

Abstract: A method and apparatus for reworking a composite structure. A composite rework patch system comprises a composite rework patch and a plurality of adhesive layers. The composite rework patch includes a first side having a contour conforming to an inconsistent area on the composite structure. The composite re patch comprises a plurality of regions having different structural properties. The plurality of adhesive layers is on the first side of the composite rework patch. The plurality of adhesive layers change in thickness within at least one region of the composite rework patch to form tapered adhesive sections.

Abstract: A patch for a structure has a rework area with an inconsistency formed therein. The patch comprises a patch body having at least two regions including a fail-safe region and a safe-life region encompassing the fail-safe region. The safe-life region has a mode I interlaminar fracture toughness that is less than the mode I interlaminar fracture toughness of the fail-safe region.

Abstract: A patch for reworking an inconsistent area in a composite structure includes a composite laminate patch adapted to cover the inconsistent area and bonded to the structure by a layer of adhesive. The patch includes a plurality of composite plies having a tapered cross section, and at least first and second regions respectively having differing fracture toughnesses.

Abstract: The disclosure provides in one embodiment a method of promoting adhesion on a composite surface. The method comprises providing a composite structure having at least one composite surface to be bonded. The method further comprises preparing the at least one composite surface. The method further comprises providing a chemical derivatization compound containing active functional groups that promote adhesion. The method further comprises depositing the chemical derivatization compound on the prepared composite surface to form a functional group-adhesive promoter derivatized layer. The method further comprises applying an adhesive layer to the derivatized layer. The method further comprises heat curing the adhesive layer to result in a bond with another structure made of a composite, a metal, or a combination thereof.

Abstract: A repair patch for reworking an inconsistent area of a composite structure includes a patch body adapted to cover the inconsistent area and having a first patch region, a second patch region outside the first patch region and a first separation zone between the first patch region and the second patch region, with the first patch region, the first separation zone and the second patch region having increasing interlaminar fracture toughness from a center to an edge of the patch body; and a layer of adhesive for bonding the patch body to the composite structure.

Abstract: A unitized composite aircraft wing includes upper and lower composite laminate wing skins that have differing stiffnesses and are bonded to a composite grid structure. The grid structure includes grid spars extending in a span-wise direction, and cross beams extending in a chord-wise direction of the wing. The grid spars include caps bonded to the upper and lower wing skins.

Abstract: A bond surface testing apparatus and method are presented. The bond surface testing apparatus comprises a solution chamber; a plurality of solution containers located in the solution chamber; a plurality of microfluidic pipettes; and an information capture module. Each solution container in the plurality of solution containers includes a microfluidic pipette in the plurality of microfluidic pipettes. A number of the plurality of microfluidic pipettes has a non-circular cross-section. The information capture module is physically associated with the solution chamber and is configured to capture information relating to bonding surface properties of the bonding surface.

Abstract: A composite laminate patch for reworking an inconsistent area in a structure has inner and outer control regions possessing differing interlaminar fracture toughnesses for controlling the advance of a disbond in the patch. One or more separation zones in the patch between the control regions aids in diffusing the fracture energy of the disbond as the disbond advances from the inner region to the outer region.

Abstract: A repair patch for reworking an inconsistent area of a composite structure includes a patch body adapted to cover the inconsistent area and having a first patch region, a second patch region outside the first patch region and a first separation zone between the first patch region and the second patch region, with the first patch region, the first separation zone and the second patch region having increasing interlaminar fracture toughness from a center to an edge of the patch body; and a layer of adhesive for bonding the patch body to the composite structure.

Abstract: A bond surface testing apparatus includes a solution chamber; a plurality of solutions in the solution chamber, the solution chamber adapted to dispense the solutions onto a bonding surface; an information capture module carried by the solution chamber and adapted to capture information relating to bonding surface properties of the bonding surface; at least one analysis module interfacing with the information capture module and adapted to analyze the bonding surface properties of the bonding surface; and a structural wettability factor prediction module interfacing with the at least one analysis module and adapted to predict a structural wettability factor based on the bonding surface properties.