Abstract: An assembly comprising first and second structural elements having aligned holes, an fastener that occupies at least respective portions of the holes without a surrounding sleeve, and a mating part that is coupled to the fastener. The fastener comprises: a head; a circular cylindrical shank extending from the head; a mating portion comprising external projections; and a transition portion disposed between the shank and the mating portion. The transition portion comprises a first radiused lead-in section that meets the shank at a shank/lead-in intersection and a second radiused lead-in section that meets the first radiused lead-in section. The first radiused lead-in section curves gradually in a first axial direction toward the mating portion and has a first profile that is a circular arc having a first radius, while the second radiused lead-in section curves abruptly in the first axial direction and has a second profile that is a circular arc having a second radius which is much smaller than the first radius.

Abstract: An electromagnetic effect suppressing termination part is provided for a fastener formed of a metallic material, the fastener having a head, a shank, and a threaded portion opposite the head. The termination part includes a main body defining an internally threaded portion configured to threadably receive the threaded portion of the fastener, the internally threaded portion defining a thread major diameter. A collar is coupled to a distal end of the main body by a frangible web, wherein the main body, collar, and frangible web are formed of a metallic core coated by a layer of dielectric material. The frangible web, when broken, presents an exposed portion of the metallic core, wherein the frangible web includes an inner surface radially outwardly offset from the thread major diameter of the internally threaded portion by a setback distance.

Abstract: Apparatus and methods for injecting molten filler material into a hole. The method in accordance with one embodiment comprises: drilling a hole in a composite layer; heating filler material comprising an electrically conductive low-melting alloy to a molten state; inserting a nozzle having an internal channel system into the hole with a gap separating the nozzle and the hole; forcing molten filler material into, through and out of the internal channel system of the nozzle and into the gap; and retracting the nozzle from the hole. The nozzle may be rotary or not rotary.

Abstract: A blind fastener system including a sleeve and, optionally, a core bolt insertable into the sleeve, wherein at least one of the sleeve and the core bolt includes a lubricious metallic coating containing at least one of tin, bismuth, indium and aluminum.

Abstract: An electromagnetic effect suppressing termination part is provided for a fastener formed of a metallic material, the fastener having a head, a shank, and a threaded portion opposite the head. The termination part includes a main body defining an internally threaded portion configured to threadably receive the threaded portion of the fastener, the internally threaded portion defining a thread major diameter. A collar is coupled to a distal end of the main body by a frangible web, wherein the main body, collar, and frangible web are formed of a metallic core coated by a layer of dielectric material. The frangible web, when broken, presents an exposed portion of the metallic core, wherein the frangible web includes an inner surface radially outwardly offset from the thread major diameter of the internally threaded portion by a setback distance.

Abstract: An electromagnetic effect suppressing termination part for a fastener formed of a metallic material, the fastener having a head, a shank, and a male threaded portion opposite the head, has a metallic core coated by a layer of dielectric material. An internal bore of the termination part includes an inner wall, a counterbore hole, and a cavity disposed therebetween. An outer surface includes an outer wall, and a frustoconical wall positioned proximally relative to the outer wall, the frustoconical wall extending radially outwardly from the outer wall and having an included angle of less than approximately 90 degrees. A seal is disposed in the counterbore hole, and the frustoconical wall is configured so that a compressive force applied to the frustoconical wall deforms the inner wall to conform to the male threaded portion of the fastener and deforms the seal to fill the cavity.

Abstract: Apparatus and methods for injecting molten filler material into a hole. The method in accordance with one embodiment comprises: drilling a hole in a composite layer; heating filler material comprising an electrically conductive low-melting alloy to a molten state; inserting a nozzle having an internal channel system into the hole with a gap separating the nozzle and the hole; forcing molten filler material into, through and out of the internal channel system of the nozzle and into the gap; and retracting the nozzle from the hole. The nozzle may be rotary or not rotary.

Abstract: A fastening device for coupling an assembly includes a fastener comprising a head, a threaded portion, and a shank extending between the head and the threaded portion. The fastening device also includes a coating formed around the fastener, wherein the coating is electrically conductive and comprises a varying thickness along the shank.

Abstract: A method for treating surfaces of fasteners made of titanium alloy or corrosion-resistant steel using a sol-gel pretreatment process prior to the application of an aluminum pigment coating. The sol-gel pretreatment process produces an interface film on the fastener surface, which interface film comprises an organometallic-based network system. The interface film aids in improving adhesion and surface roughness when fasteners are used in interference fit conditions (i.e., the hole diameter is smaller than the fastener shank diameter).

Abstract: An assembly comprising first and second structural elements having aligned holes, an fastener that occupies at least respective portions of the holes without a surrounding sleeve, and a mating part that is coupled to the fastener. The fastener comprises: a head; a circular cylindrical shank extending from the head; a mating portion comprising external projections; and a transition portion disposed between the shank and the mating portion. The transition portion comprises a first radiused lead-in section that meets the shank at a shank/lead-in intersection and a second radiused lead-in section that meets the first radiused lead-in section. The first radiused lead-in section curves gradually in a first axial direction toward the mating portion and has a first profile that is a circular arc having a first radius, while the second radiused lead-in section curves abruptly in the first axial direction and has a second profile that is a circular arc having a second radius which is much smaller than the first radius.

Abstract: An assembly comprising first and second structural elements having aligned holes, a fastener that occupies at least respective portions of the holes without a surrounding sleeve, and a mating part that is coupled to the fastener. The fastener comprises: a head; a circular cylindrical shank extending from the head; a mating portion comprising external projections; and a transition portion disposed between the shank and the mating portion. The transition portion comprises a tapered lead-in section that meets the shank at a shank/lead-in intersection and a radiused lead-in section that meets the tapered lead-in section. The tapered lead-in section tapers gradually in a first axial direction toward the mating portion and has a first profile that is linear and a taper angle equal to or less than 20 degrees, while the radiused lead-in section curves abruptly in the first axial direction and has a second profile that is a circular arc having a radius.