Abstract: Ignition-quenching covers are configured to quench an ignition event in a combustible environment triggered by an ignition source associated with an ignition-risk structure. Ignition-quenching covers comprise a porous body that includes two or more porous elements and are configured to cover the ignition-risk structure, wherein the ignition-risk structure is associated with a potential ignition source that may produce the ignition event in the combustible environment. The porous body defines passages sized to quench the ignition event. Methods comprise installing a porous ignition-quenching cover over an ignition-risk structure to prevent bulk combustion, e.g., of a fuel vapor in a fuel tank, due to an ignition event associated with the ignition-risk structure.

Abstract: Ignition-quenching covers are configured to quench an ignition event in a combustible environment triggered by an ignition source associated with an ignition-risk structure. Ignition-quenching covers comprise a porous body that includes two or more porous elements and are configured to cover the ignition-risk structure, wherein the ignition-risk structure is associated with a potential ignition source that may produce the ignition event in the combustible environment. The porous body defines passages sized to quench the ignition event. Methods comprise installing a porous ignition-quenching cover over an ignition-risk structure to prevent bulk combustion, e.g., of a fuel vapor in a fuel tank, due to an ignition event associated with the ignition-risk structure.

Abstract: Ignition-quenching systems include an ignition-risk structure that extends from a support structure into a combustible environment and include a porous ignition-quenching cover that substantially covers the ignition-risk structure. The ignition-quenching cover is configured to quench an ignition event triggered by an ignition source associated with the ignition-risk structure. Ignition-quenching covers generally include a porous body. The porous body may include one or more porous elements. Methods according to the present disclosure include installing a porous ignition-quenching cover over an ignition-risk structure to prevent bulk combustion, e.g., of a fuel vapor in a fuel tank, due to an ignition event associated with the ignition-risk structure.

Abstract: An example method for producing thrust includes injecting a neutral gas into a cavity between an outer electrode and an inner electrode of a thruster, ionizing the neutral gas within the cavity into a plasma, causing the plasma to form into a plasma arc between the end of the inner electrode and the exhaust orifice of the outer electrode, generating a magnetic field that applies pressure on the plasma arc, maintaining stability of the plasma arc, and exhausting the plasma arc out of the exhaust orifice based on the applied pressure of the magnetic field, thereby producing thrust.

Abstract: Propagating brush discharge testing systems include an initiation electrode, a high-voltage switch, a sensor, and a controller. The initiation electrode has an exposed tip positioned adjacent to a surface of a test article. The high-voltage switch is configured to selectively isolate the initiation electrode from ground potential. The sensor is positioned and configured to detect a propagating brush discharge between the initiation electrode and the test article. The controller is programmed to operate the high-voltage switch to ground the initiation electrode.

Abstract: A method for placing electrical conductors interior to a composite structure prior to curing. A laminate stack is formed by assembling one or more composite layers, wherein the composite layers are pre-impregnated with a resin. One or more electrical conductors are placed on at least one of the composite layers prior to curing the laminate stack. One or more electrical insulators is optionally placed in proximity to one or more of the electrical conductors in at least one of the composite layers prior to curing the laminate stack. The laminate stack, including the composite layers, the electrical conductors, and the electrical insulators, is then cured to create the composite structure.

Abstract: A method and apparatus for measuring a dynamic tensile stress and/or tensile strain response of a material such as an elastic material and/or a ductile material. The apparatus may include a striker bar, a stretcher bar, and a drive assembly configured to propel the striker bar toward the stretcher bar. The apparatus may further include a stationary specimen mount and a movable specimen mount that receive a test sample. The striker bar and the stretcher bar of the apparatus may provide a continuous stress on the test sample and an accurate tensile stress/strain measurement.

Abstract: Propagating brush discharge testing systems include an initiation electrode, a high-voltage switch, a sensor, and a controller. The initiation electrode has an exposed tip positioned adjacent to a surface of a test article. The high-voltage switch is configured to selectively isolate the initiation electrode from ground potential. The sensor is positioned and configured to detect a propagating brush discharge between the initiation electrode and the test article. The controller is programmed to operate the high-voltage switch to ground the initiation electrode.

Abstract: Propagating brush discharge testing systems may include a dielectric layer, an initiation electrode, a high-voltage switch, an optical sensor, and a controller. The initiation electrode has an exposed tip positioned adjacent to a surface of the dielectric layer. The high-voltage switch is configured to selectively isolate the initiation electrode from ground potential. The optical sensor is positioned and configured to sense light generated at the surface due to a propagating brush discharge. The controller is programmed to operate the high-voltage switch to ground the initiation electrode and to operate the optical sensor to collect light from the propagating brush discharge. Propagating brush discharge testing methods include positioning an exposed tip of an initiation electrode with respect to a surface of a dielectric layer, then charging the surface, and then grounding the initiation electrode to neutralize charge on the surface (generally causing a propagating brush discharge).

Abstract: A method for promoting electrical conduction between metallic components and composite materials. A composite body is coated with an adhering layer comprising a conductive material, and a metallic component is electrically connected to the conductive material of the adhering layer, when the metallic component is coupled to the composite body. The adhering layer is deposited inside a hole in the composite body, and/or along an edge of the hole, and/or on at least a portion of a surface of the composite body. The composite body is a structure of an aircraft or other vehicle comprised of composite materials formed from carbon fiber-reinforced polymers (CFRPs), the metallic component is a fastener or is positioned at an interface between the fastener and the composite body, and the electrical connection is made as part of a lightning protection system, an electromagnetic effects (EME) management system, or grounding system.

Abstract: Propagating brush discharge testing systems may include a dielectric layer, an initiation electrode, a high-voltage switch, an optical sensor, and a controller. The initiation electrode has an exposed tip positioned adjacent to a surface of the dielectric layer. The high-voltage switch is configured to selectively isolate the initiation electrode from ground potential. The optical sensor is positioned and configured to sense light generated at the surface due to a propagating brush discharge. The controller is programmed to operate the high-voltage switch to ground the initiation electrode and to operate the optical sensor to collect light from the propagating brush discharge. Propagating brush discharge testing methods include positioning an exposed tip of an initiation electrode with respect to a surface of a dielectric layer, then charging the surface, and then grounding the initiation electrode to neutralize charge on the surface (generally causing a propagating brush discharge).

Abstract: An apparatus and a method for simulating a mechanical stress applied to a sealant from a lightning strike upon an aircraft is provided. The apparatus comprises a specimen, a test fixture, and a capacitor. The specimen comprises an electrically non-conductive sealant for an aircraft fuel tank having a cylindrical shape, and an electrically conductive wire centered axially within the sealant. The test fixture secures the specimen during testing. The capacitor is electrically coupled to the test fixture, and simulates a lightning strike upon the aircraft by vaporizing the wire with a current to generate a mechanical shock to the sealant.

Abstract: A method for promoting electrical conduction between metallic components and composite materials. A composite body is coated with an adhering layer comprising a conductive material, and a metallic component is electrically connected to the conductive material of the adhering layer, when the metallic component is coupled to the composite body. The adhering layer is deposited inside a hole in the composite body, and/or along an edge of the hole, and/or on at least a portion of a surface of the composite body. The composite body is a structure of an aircraft or other vehicle comprised of composite materials formed from carbon fiber-reinforced polymers (CFRPs), the metallic component is a fastener or is positioned at an interface between the fastener and the composite body, and the electrical connection is made as part of a lightning protection system, an electromagnetic effects (EME) management system, or grounding system.

Abstract: A method for placing electrical conductors interior to a composite structure prior to curing. A laminate stack is formed by assembling one or more composite layers, wherein the composite layers are pre-impregnated with a resin. One or more electrical conductors are placed on at least one of the composite layers prior to curing the laminate stack. One or more electrical insulators is optionally placed in proximity to one or more of the electrical conductors in at least one of the composite layers prior to curing the laminate stack. The laminate stack, including the composite layers, the electrical conductors, and the electrical insulators, is then cured to create the composite structure.

Abstract: A method and apparatus for measuring a dynamic tensile stress and/or tensile strain response of a material such as an elastic material and/or a ductile material. The apparatus may include a striker bar, a stretcher bar, and a drive assembly configured to propel the striker bar toward the stretcher bar. The apparatus may further include a stationary specimen mount and a movable specimen mount that receive a test sample. The striker bar and the stretcher bar of the apparatus may provide a continuous stress on the test sample and an accurate tensile stress/strain measurement.

Abstract: According to an embodiment a current return network assembly, for an aircraft having a predetermined potential lightning strike zone, is mounted within the predetermined potential lightning strike zone. The current return network assembly includes an electrically conductive honeycomb central core that conducts electrical current both through the assembly and through the predetermined potential lightning strike zone. The electrical current is caused by a lightning strike on the aircraft at the predetermined potential lightning strike zone. According to an embodiment, an aircraft has a predetermined potential lightning strike zone. A current return network assembly is within the zone. An electrically conductive honeycomb central core is provided for conducting electrical current through the assembly and through the zone wherein the electrical current has been caused by a lightning strike on the aircraft at the zone.

Abstract: Embodiments described herein provide apparatus and a method for simulating a mechanical stress applied to a sealant from a lightning strike upon an aircraft. One embodiment comprises a specimen, a test fixture, and a capacitor. The specimen comprises an electrically non-conductive sealant for an aircraft fuel tank having a cylindrical shape, and an electrically conductive wire centered axially within the sealant. The test fixture secures the specimen during testing. The capacitor is electrically coupled to the test fixture, and simulates a lightning strike upon the aircraft by vaporizing the wire with a current to generate a mechanical shock to the sealant.

Abstract: Ignition-quenching systems include an ignition-risk structure that extends from a support structure into a combustible environment and include a porous ignition-quenching cover that substantially covers the ignition-risk structure. The ignition-quenching cover is configured to quench an ignition event triggered by an ignition source associated with the ignition-risk structure. Ignition-quenching covers generally include a porous body. The porous body may include one or more porous elements. Methods according to the present disclosure include installing a porous ignition-quenching cover over an ignition-risk structure to prevent bulk combustion, e.g., of a fuel vapor in a fuel tank, due to an ignition event associated with the ignition-risk structure.

Abstract: A method for sealing an interface to attenuate high energy currents and voltages traveling thereacross may include forming a cover defining an inner volume shaped to enclose the interface; forming a filled sealant including a semi-rigid sealant mixed with a filler having a multiplicity of discrete particles of different composition than the semi-rigid sealant; placing the filled sealant within the inner volume; and placing the cover containing the filled sealant over the interface such that the filled sealant is adjacent the interface.

Abstract: An apparatus comprises a housing, a core located in the housing, a coil unit associated with the core and located in the housing, and a backing plate made of a high-permeability material. The apparatus may be used for generating high clamping forces between materials that are interposed between the core and the backing plate such that manufacturing operations can be carried out. The core has a cross section with an elongate shape. The coil unit is configured to generate magnetic fields and has the elongate shape.