Abstract: There is provided a laminated composite structure having improved impact damage resistance and improved strength. The laminated composite structure has a plurality of stacked layers of a composite material. The plurality of stacked layers have one or more interlaminar corrugations formed within the plurality of stacked layers. Each interlaminar corrugation has a substantially sinusoidal shaped profile, and has a depth and a length dependent on a size of the laminated composite structure formed. The laminated composite structure with the one or more interlaminar corrugations has improved strength and improved impact damage resistance at an exposed edge of the laminated composite structure, when the exposed edge is subjected to an impact force.

Abstract: There is provided a laminated composite structure having improved impact damage resistance and improved strength. The laminated composite structure has a plurality of stacked layers of a composite material. The plurality of stacked layers have one or more interlaminar corrugations formed within the plurality of stacked layers. Each interlaminar corrugation has a substantially sinusoidal shaped profile, and has a depth and a length dependent on a size of the laminated composite structure formed. The laminated composite structure with the one or more interlaminar corrugations has improved strength and improved impact damage resistance at an exposed edge of the laminated composite structure, when the exposed edge is subjected to an impact force.

Abstract: Disclosed herein is a method of repairing surface damage in an exterior surface of a hollow bladder, made of a cured elastomer. The method comprises placing first strips, made of an uncured elastomer, at least partially within the surface damage in the exterior surface of the hollow bladder in a side-by-side arrangement. The method also comprises sealing the surface damage, the first strips, and a portion of the exterior surface surrounding the surface damage in a vacuum bag. The method further comprises reducing pressure within the vacuum bag relative to outside the vacuum bag. The method additionally comprises while the pressure within the vacuum bag is reduced, heating the first strips from within the vacuum bag to cure the first strips.

Abstract: There is provided a laminated composite structure having improved impact damage resistance and improved strength. The laminated composite structure has a plurality of stacked layers of a composite material. The plurality of stacked layers have one or more interlaminar corrugations formed within the plurality of stacked layers. Each interlaminar corrugation has a substantially sinusoidal shaped profile, and has a depth and a length dependent on a size of the laminated composite structure formed. The laminated composite structure with the one or more interlaminar corrugations has improved strength and improved impact damage resistance at an exposed edge of the laminated composite structure, when the exposed edge is subjected to an impact force.

Abstract: Disclosed herein is a method of repairing surface damage in an exterior surface of a hollow bladder, made of a cured elastomer. The method comprises placing first strips, made of an uncured elastomer, at least partially within the surface damage in the exterior surface of the hollow bladder in a side-by-side arrangement. The method also comprises sealing the surface damage, the first strips, and a portion of the exterior surface surrounding the surface damage in a vacuum bag. The method further comprises reducing pressure within the vacuum bag relative to outside the vacuum bag. The method additionally comprises while the pressure within the vacuum bag is reduced, heating the first strips from within the vacuum bag to cure the first strips.

Abstract: Methods for measuring out-of-plane wrinkles in composite laminates are described. An example method includes scanning a first side of a composite laminate with an ultrasonic transducer. The method further includes locating an out-of-plane wrinkle of the composite laminate on a B-scan ultrasound image generated in response to the scanning of the first side of the composite laminate. The method further includes associating a first marker with the B-scan ultrasound image, the first marker determined based on a location of a crest of the out-of-plane wrinkle on the B-scan ultrasound image. The method further includes associating a second marker with the B-scan ultrasound image, the second marker determined based on a location of a trough focal point of the out-of-plane wrinkle on the B-scan ultrasound image. The method further includes determining an amplitude of the out-of-plane wrinkle based on a distance between the first marker and the second marker.

Abstract: A mandrel for composite fabrication includes an open cell foam carrier and at least one vacuum bag enclosing the open cell foam carrier.

Abstract: There is provided a laminated composite structure having improved impact damage resistance and improved strength. The laminated composite structure has a plurality of stacked layers of a composite material. The plurality of stacked layers have one or more interlaminar corrugations formed within the plurality of stacked layers. Each interlaminar corrugation has a substantially sinusoidal shaped profile, and has a depth and a length dependent on a size of the laminated composite structure formed. The laminated composite structure with the one or more interlaminar corrugations has improved strength and improved impact damage resistance at an exposed edge of the laminated composite structure, when the exposed edge is subjected to an impact force.

Abstract: Methods for measuring out-of-plane wrinkles in composite laminates are described. An example method includes scanning a first side of a composite laminate with an ultrasonic transducer. The method further includes locating an out-of-plane wrinkle of the composite laminate on a B-scan ultrasound image generated in response to the scanning of the first side of the composite laminate. The method further includes associating a first marker with the B-scan ultrasound image, the first marker determined based on a location of a crest of the out-of-plane wrinkle on the B-scan ultrasound image. The method further includes associating a second marker with the B-scan ultrasound image, the second marker determined based on a location of a trough focal point of the out-of-plane wrinkle on the B-scan ultrasound image. The method further includes determining an amplitude of the out-of-plane wrinkle based on a distance between the first marker and the second marker.

Abstract: An apparatus for forming a material layer onto a form tool may include at least one nosepiece configured to laterally sweep a ply carrier onto a form tool contour. The apparatus may include a pair of tension arms configured to support opposing lateral sides of a ply carrier having a material layer mounted to a lower surface thereof. The apparatus may include one or more actuators configured to position the tension arms during forming of the ply carrier to the form tool contour. The one or more actuators may be configured to sense and control lateral tension in the ply carrier during forming of the ply carrier to the form tool contour.

Abstract: A composite stiffener is fabricated using preforms of laminated, unidirectional composite tape. The stiffener includes a void that is reinforced by a filler wrapped with a structural adhesive. The surfaces of the preforms surrounding the void include a layer of composite fabric which is bonded to the filler by the adhesive, thereby increasing the toughness of stiffeners around the void and improving pull-off strength of the stiffener.

Abstract: A method and system of preparing a releasable underlying support for use in preparing a composite laminate is presented where a base tool is a covered with a conformable thin sheet on the tooling surface of a base tool, where the thin sheet is configured with one high tack surface side and an opposite side having a non-tack surface in contact with the tooling surface. The non-tack surface side will allow release of laid up pre-cure composite lamina that can then be cured on a separate curing tool. The thin sheet is positioned over the base tool and a vacuum source and sealed around the perimeter edge of the base tool. Drawing a vacuum causes the non-tack surface side of the film to be drawn downward into contact with the tooling surface. Plies of pre-cure lamina can then be added to the base tool covering and adhering to the high tack surface side.

Abstract: An apparatus for forming a material layer onto a form tool may include at least one nosepiece configured to laterally sweep a ply carrier onto a form tool contour. The apparatus may include a pair of tension arms configured to support opposing lateral sides of a ply carrier having a material layer mounted to a lower surface thereof. The apparatus may include one or more actuators configured to position the tension arms during forming of the ply carrier to the form tool contour. The one or more actuators may be configured to sense and control lateral tension in the ply carrier during forming of the ply carrier to the form tool contour.

Abstract: A mandrel for composite fabrication includes an open cell foam carrier and at least one vacuum bag enclosing the open cell foam carrier.

Abstract: A mandrel for composite fabrication includes an open cell foam carrier and at least one vacuum bag enclosing the open cell foam carrier.

Abstract: A method and system of preparing a releasable underlying support for use in preparing a composite laminate is presented where a base tool is a covered with a conformable thin sheet on the tooling surface of a base tool, where the thin sheet is configured with one high tack surface side and an opposite side having a non-tack surface in contact with the tooling surface. The non-tack surface side will allow release of laid up pre-cure composite lamina that can then be cured on a separate curing tool. The thin sheet is positioned over the base tool and a vacuum source and sealed around the perimeter edge of the base tool. Drawing a vacuum causes the non-tack surface side of the film to be drawn downward into contact with the tooling surface. Plies of pre-cure lamina can then be added to the base tool covering and adhering to the high tack surface side.

Abstract: A collapsible bladder has flexible outer walls and at least one strut inside the enclosure. The strut is connected to the outer walls and controls the shape into which the enclosure may be collapsed.

Abstract: Methods of forming a collapsible mandrel are disclosed herein. An example method disclosed herein includes forming a layup on a substrate by providing a first layer of rubber, positioning a reinforcement strip on the first layer of rubber, providing first and second release films in spaced apart from each other adjacent the reinforcement strip to expose a portion of the reinforcement strip, providing a second layer of rubber overlying the exposed portion of the reinforcement strip, and laminating the first and second layers of rubber to the reinforcement strip. The release films to prevent the first and second layers of rubber from adhering to each other and the reinforcement strip such that non-adhered ends of the first and second layers of rubber and the reinforcement strip define flaps. The method includes placing the layup in a cavity of a mold forming part of a tool assembly, consolidating the layup when the layup is in the cavity of the mold, and curing the layup to form the collapsible mandrel.

Abstract: A collapsible bladder has flexible outer walls and at least one strut inside the enclosure. The strut is connected to the outer walls and controls the shape into which the enclosure may be collapsed.

Abstract: A flyback converter uses primary side sensing to sense the output voltage for regulation feedback. A comparator on the primary side detects whether the output voltage has exceeded a predetermined regulated voltage by a first threshold to detect an over-voltage condition, resulting from a current generated by the converter exceeding the load current. Triggering of the comparator causes the converter to enter a non-switching sleep mode, whereby the output voltage droops over a period of time. When the output voltage has drooped below the predetermined regulated voltage by a second threshold, a synchronous rectifier is controlled to turn on, then off, to generate a pulse in the primary winding. Upon detection of the pulse, the sleep mode is terminated, and normal operation resumes until a regulated voltage is achieved or until the first threshold is again exceeded by the output voltage.