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: 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 disband advances from the inner region to the outer region.

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 patch for reworking an inconsistent area of a composite structure comprises a composite laminate patch and a bond joint between the patch and the structure. The bond joint including at least first and second regions respectively having differing properties for releasing strain energy around the inconsistent area at different rates.

Abstract: The condition of a bond surface is determined. A 3-D wettability tension curve is generated for the bond surface which represents a range of possible wettings of an adhesive on the bond surface that may result in a bond joint of acceptable quality. At least three surface energies on the bond surface are measured, and the wettability curve is used to determine whether the condition of the bond surface is acceptable based on the measured bonding surface energies.

Abstract: A strain measurement device to assess the integrity of a structural repair to a surface comprises a detector, a processor, and a memory module coupled to the processor. The memory module comprises logic instructions stored in a computer readable medium which, when executed by the processor, configure the processor to use the detector to obtain a first strain measurement from an external strain indicator, use the detector to obtain a second strain measurement from the measurement sensor after at least one stress test is applied to the structural repair, and generate a signal when a difference between the first strain measurement and the second strain measurement exceeds a threshold.

Abstract: A protocol for determining process parameters for debulking composite laminates is established using a standardized double vacuum debulk (DVD) process. This allows for the development of a rapid fabrication process for thick laminates of toughened carbon/epoxy composite materials. The protocol provides for obtaining cure and current consolidation information of a composite material system as a preliminary baseline. A test matrix is prepared for varying time/temp profiles to pursue better results or find process limits and the testing defined by the matrix is run with variations of time/temp DVD profiles to confirm data values. Results for the process variations in the test matrix are then assessed. An optimum consolidation is determined and process points are defined at which quality drops off. The protocol results are then applied to part preparation for the material tested.

Abstract: A protocol for determining process parameters for debulking composite laminates is established using a standardized a double vacuum debulk (DVD) process. This allows for the development of a rapid fabrication process for thick laminates of toughened carbon/epoxy composite materials. For rework, a single piece multilayer patch is made available for bonding with an adhesive layer to a prepared structural area.

Abstract: A deterministic non-destructive evaluation system for composite damage assessment and repair includes structure of interest, non-destructive evaluation data and strength test data obtained on the structure of interest, finite element analysis performed on a structural model modified by the non-destructive data and the strength test data, a strength-to-indication correlation based on the finite element analysis and deterministic non-destructive evaluation predictions and recommendations based on the strength-to-indication correlation.

Abstract: A composite laminate comprises a stack of unidirectional fiber reinforced composite plies arranged in a fiber orientation sequence providing the laminate with quasi-isotropic properties.

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: A patch for reworking an inconsistent area of a composite structure comprises a composite laminate patch and a bond joint between the patch and the structure. The bond joint including at least first and second regions respectively having differing properties for releasing strain energy around the inconsistent area at different rates.

Abstract: A protocol for determining process parameters for debulking composite laminates is established using a standardized a double vacuum debulk (DVD) process. This allows for the development of a rapid fabrication process for thick laminates of toughened carbon/epoxy composite materials. For rework, a single piece multilayer patch is made available for bonding with an adhesive layer to a prepared structural area.

Abstract: A method for repairing a damaged area, referred to as the repair area, of a composite structure comprises steps of: making alignment markings on the repair area; fabricating a pair of alignment templates; preparing the repair area for a hot bonded, vacuum bagged repair; assembling a repair patch; consolidating the repair patch; heating the repair patch; transferring and aligning the repair patch to the repair area; vacuum bagging, heating, and cooling the repair patch for a partial cure at the repair area; heating and cooling the repair patch in an oven; and bonding the repair patch to the repair area.

Abstract: A method for repairing a damaged area, referred to as the repair area, of a composite structure comprises steps of: making alignment markings on the repair area; fabricating a pair of alignment templates; preparing the repair area for a hot bonded, vacuum bagged repair; assembling a repair patch; consolidating the repair patch; heating the repair patch; transferring and aligning the repair patch to the repair area; vacuum bagging, heating, and cooling the repair patch for a partial cure at the repair area; heating and cooling the repair patch in an oven; and bonding the repair patch to the repair area.