Abstract: A method of installing fastening elements, and rivetless fasteners for use with the method. Rivetless nutplate fasteners are installed in metal structures by providing flush fit barrel shaped plug or bushing portions in a hole in the structure as defined by an edge wall. The barrel portion is acted upon axially, and expanded radially outward toward the edge wall of the hole, to provide an interference fit. The ends of the barrel portion are machined as desired for flushness. Also, a hole is installed as necessary. Rivetless nutplates are easily installed, and the installation enhances fatigue life of the hole surrounding the barrel of the nutplate.

Abstract: A method for cold working metal structures. A compound indenter is used to produce deformation in a workpiece, to provide a selected beneficial residual stress profile, to provide improved fatigue life structures with minimal manufacturing steps. A compound indenter deforms a workpiece, resulting in dimples therein. A relatively uniform beneficial residual stress profile is provided at the surface and at the midplane of apertures in a workpiece, so as to improve overall fatigue life. A compound indenter tool having a first, elongate indenter with a shaped indenter surface portion, and a second shaped indenter surrounding the first indenter and forming an annular shoulder recessed from the surface portion of the first indenter, is used. Optionally, a foot having a bottom portion is used to confiningly surround an indenter during application of deforming force to the surface of a workpiece, to prevent deformation of adjacent workpiece surface.

Abstract: Metal cold-working tooling and a method of employing such tooling. The tooling is used to produce deformation in a workpiece, to provide a selected beneficial residual stress profile in the workpiece, in order to provide high fatigue life structures in a minimum number of manufacturing steps. An indenter is used to coldwork a workpiece, causing dimples in the workpiece. Preferably, the dimples are provided with a shape formed by application of a uniform pressure profile to the workpiece surface. As optimized, a relatively uniform beneficial residual stress profile is provided at both the surface and at the midplane apertures in a workpiece, so as to improve overall fatigue life. Also, an improved indenter tool profile shape is described, having a smoothly curved indenter surface portion. And, the use of consumable lamina wafers provides the benefit of easy application of uniform stress profile to a workpiece.

Abstract: A method of manufacturing a fatigue life enhanced product from a plurality of workpiece parts. At least one fatigue enhancing operation is performed on a first workpiece at a first work station. At least one fatigue enhancing operation is performed on a second workpiece at a second work station. The first and second workpieces are transferred to a first assembly station, where the workpieces are joined to form a fatigue life enhanced product. Aerostructures manufactured according to the method may include components fabricated at different locations to have fatigue life enhancing properties, especially in bounding material adjacent to holes designed to accommodate fasteners. By use of the method, the final assembly step can thus avoid the necessity to include the processing of holes to enhance fatigue life, since this step has been performed prior to bringing components into position to be joined in the final shape or assembly of the airframe.

Abstract: A compound indenter for metal coldwork, and a method of employing such tooling. The compound indenter tool is used to produce deformation in a workpiece structure, to provide a selected beneficial residual stress profile in the workpiece, in order to provide high fatigue life structures in a minimum number of manufacturing steps. Preferably, action of a compound indenter causes deformation of the workpiece, causing dimples in the workpiece. By optimized use of the method, a relatively uniform beneficial residual stress profile is provided at both the surface and at the midplane apertures in a workpiece, so as to improve overall fatigue life. An improved, compound indenter tool profile shape is described, having a first, elongate indenter with a shaped indenter surface portion, and a second shaped indenter surrounding the first indenter and forming an annular shoulder recessed from the surface portion of the first indenter.

Abstract: Metal coldworking tooling and a method of employing such tooling. The tooling is used to produce deformation in a workpiece, preferably via use of stress waves, to provide a selected beneficial residual stress profile in the workpiece, in order to provide high fatigue life structures in a minimum number of manufacturing steps. Preferably, action of an indenter causes propagation of stress waves to coldwork a workpiece, causing dimples in the workpiece. Preferably, the dimples are provided with a shape formed by application of a uniform pressure profile to the workpiece surface. By optimized use of the method, a relatively uniform beneficial residual stress profile is provided at both the surface and at the midplane apertures in a workpiece, so as to improve overall fatigue life. An improved indenter tool profile shape is described, having a smoothly curved indenter surface portion.

Abstract: Metal coldworking tooling and a method of employing such tooling. The tooling is used to produce deformation in a workpiece, preferably via use of stress waves, to provide a selected beneficial residual stress profile in the workpiece, in order to provide high fatigue life structures in a minimum number of manufacturing steps. Preferably, action of an indenter causes propagation of stress waves to coldwork a workpiece, causing dimples in the workpiece. Preferably, the dimples are provided with a shape formed by application of a pre-selected pressure profile to the workpiece surface. By optimized use of the method, a relatively uniform beneficial residual stress profile is provided at both the surface and at the midplane apertures in a workpiece, so as to improve overall fatigue life.

Abstract: Tooling and a method of employing tooling to produce beneficial stress waves in a substrate to provide high fatigue life structures. Stress waves are provided to work a substrate, causing dimples in the workpiece, along a uniform pressure profile in the workpiece. By use of the method, uniform beneficial residual stress is provided at surface and midplane apertures in a workpiece, so as to improve overall fatigue life. An improved tool shape is described, having a smooth curve, rather than a flat punch. Also, the use of a consumable wafer provides additional uniform stress profile benefits.

Abstract: Metal coldworking tooling and a method of employing such tooling. The tooling is used to produce deformation in a workpiece, preferably via use of stress waves, to provide a selected beneficial residual stress profile in the workpiece, in order to provide high fatigue life structures in a minimum number of manufacturing steps. Preferably, action of an indenter causes propagation of stress waves to coldwork a workpiece, causing dimples in the workpiece. Preferably, the dimples are provided with a shape formed by application of a uniform pressure profile to the workpiece surface. By optimized use of the method, a relatively uniform beneficial residual stress profile is provided at both the surface and at the midplane apertures in a workpiece, so as to improve overall fatigue life. An improved indenter tool profile shape is described, having a smoothly curved indenter surface portion.