Fatigue resistant fastener and method of manufacturing joints therewith

Claim 1

For fatigue resistant structural joints, an interference fit, relatively nondeformable metal, headed, round pin-type fastener cooperable with structural members of relatively deformable metal to be fastened having a round straight fastener receiving hole therein, said fastener comprising an elongated round shank terminating at one end in a fastener head having an underside surface, said shank comprising a main body portion of straight cylindrical configuration larger in diameter than said hole and that terminates at its end opposite the head through a convexly rounded lead-in shoulder and, beyond such shoulder, in a protruding locking end portion of smaller diameter than said main body portion, said shank main body portion undergoing progressive expansion of diameter from said straight cylindrical configuration through a concave substantially curvilinear profile lengthwise thereof toward the fastener head with a relatively large starting radius of curvature tangential to said cylindrical configuration and continuing therefrom through a final concave curvature of relatively small radius fairing smoothly therewith and with the underside surface of the fastener head.

Claim 13

The method of manufacturing fatigue-resistant structural joints with interference fit fasteners joining together structural members of relatively deformable metal by fasteners of relatively nondeformable metal, headed, round pin configuration, said method comprising: forming a straight fastener-receiving round hole through mutually superimposed structural members, forcing through said hole the body of such a fastener larger in diameter throughout its length than the diameter of the hole, which body diameter progressively increases in a concave curvilinear profile starting tangentially therewith at relatively large radius adjacent its end initially inserted, said curvilinear profile terminating with smooth curvilinearity through a relatively small radius on the underside of said head, continuing the insertion and increasing the force of insertion as the curvilinear profile diameter entering the hole increases thereby to increase the wall stress in the structural member around the hole in the region thereof adjacent to a fastener head, until the fastener head itself is forced into contact with the adjacent structural member, with the opposite end portion of the fastener protruding through the structural members, and locking the fastener in the hole by means including said protruding end portion operable to react against the adjacent structural member and thereby to exert tension stress lengthwise in the fastener.

Claim 14

The method of manufacturing fatigue-resistant structural joints with interference fit fasteners joining together structural members of relatively deformable metal by fasteners of relatively nondeformable metal, headed, round pin configuration, said method comprising: forming a straight fastener-receiving round hole through mutually superimposed structural members, forcing through said hole the body of such a fastener larger in diameter throughout its length than the diameter of the hole, which body diameter progressively increases in a concave curvilinear profile starting tangentially therewith at relatively large radius adjacent its end initially inserted, said curvilinear profile terminating with smooth curvilinearity through a relatively small radius on the underside of said head, continuing the insertion and increasing the force of insertion as the curvilinear profile diameter entering the hole increases thereby to increase the wall stress in the structural member around the hole in the region thereof adjacent to a fastener head, until the fastener head itself is forced into contact with the adjacent structural member, with the opposite end portion of the fastener protruding through the structural members, and locking the fastener in the hole by means including said protruding end portion operable to react against the adjacent structural member and thereby to exert tension stress lengthwise in the fastener.