Abstract: An apparatus is provided for finite element modeling and analysis of a structural product. A pre-processing system may produce a finite element model of a structural product including component parts joined by a fastener. The finite element model may represent the product by respective meshes of elements including shell or solid elements for the component parts, and beam and spring elements for the fastener in which at least one spring element has an axial offset from the shell or solid elements with respect to an axis of the fastener. A processing system may perform a finite element method (FEM) failure analysis of the finite element model under an external load that is transferable from the component parts to the fastener. The FEM failure analysis may produce an output that indicates a behavior of the fastener, and the FEM failure analysis may predict a component failure rate of the fastener based on the behavior.

Abstract: A member has a wave inhibitor adapted to control the effects of a wave of longitudinally displaced material positioned ahead of an expansion mandrel used to expand the member. The wave inhibitor has a decreasing transverse cross-sectional area to diminish the effects attributable to the wave, such as workpiece distortions, material upset of the workpiece, lengthening of the member, and excessively high strains in the workpiece. The wave inhibitor can also induce radially compressive stresses in the workpiece and produce an interference fit.

Abstract: An apparatus is provided for finite element modeling and analysis of a structural product. A pre-processing system may produce a finite element model of a structural product including component parts joined by a fastener. The finite element model may represent the product by respective meshes of elements including shell or solid elements for the component parts, and beam and spring elements for the fastener in which at least one spring element has an axial offset from the shell or solid elements with respect to an axis of the fastener. A processing system may perform a finite element method (FEM) failure analysis of the finite element model under an external load that is transferable from the component parts to the fastener. The FEM failure analysis may produce an output that indicates a behavior of the fastener, and the FEM failure analysis may predict a component failure rate of the fastener based on the behavior.

Abstract: A member has a wave inhibitor adapted to control the effects of a wave of longitudinally displaced material positioned ahead of an expansion mandrel used to expand the member. The wave inhibitor has a decreasing transverse cross-sectional area to diminish the effects attributable to the wave, such as workpiece distortions, material upset of the workpiece, lengthening of the member, and excessively high strains in the workpiece. The wave inhibitor can also induce radially compressive stresses in the workpiece and produce an interference fit.

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 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.