Abstract
The residual stresses in and around riveted joints, formed with an electromagnetic riveter (as used in production of the Airbus A380 wing) have been investigated. Synchrotron X-ray and neutron diffraction were used to assess the stresses introduced into skin panel sections by installation of the fasteners. The stress profiles thus obtained exhibited an annular compressive zone, peaking around 400 MPa, around the fastener hole, balanced by tensile residual stresses (at a maximum of approximately 150 MPa) in the bulk material. The in-plane stress field was found to resemble that expected around a cold expanded hole. An analytical solution for the residual stresses in an autofrettaged tube was compared with the stresses around the rivet, allowing estimation of the pressures applied by the rivet to the fastener hole during rivet placement. These pressures were related to the yield stress of the skin material being riveted. This pressure produces a plastic misfit around the hole that places the rivet/hole interface under significant hoop compression. This compressive region is expected to confer significant advantages in terms of the fatigue lifetime of the riveted joints.
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