Effects of Clearance Fit and Friction Coefficient on Triple-Row Riveted Lap Joints

Effects of fastener clearance fit, friction coefficient, and corrosion pillowing on the stress state in triple-row riveted lap joints were studied numerically using three-dimensional finite element methods. The material elastoplastic constitutive relationship and geometric nonlinear properties, as well as nonlinear contact boundary conditions, were included in the numerical simulations. The numerical modeling was validated using experimental measurements of the rivet driven head deformation and in-situ strains. The lap joints were loaded in tension after riveting. Three different clearance fits, three different friction coefficients, and four corrosion pillowing conditions were analyzed. The stress variation along prescribed paths during the tensile loading stage is discussed for each of these conditions. Full-field contours of the friction and maximum principal stresses during the tensile loading stage were investigated. Numerical results showed that a small increase in the clearance fit considerably increased the joint stress magnitude. The clearance fit magnitude also affected the maximum stress location in the vicinity at the top fastener hole. A large friction coefficient increased the contact and friction stresses in the hole vicinity. These results could explain the scatter degree of the fatigue data and could be used to improve the manufacture quality for high fatigue-rated riveted lap joints. Serious corrosion pillowing significantly increased the stress magnitude at both the middle and top hole regions, and led to the co-existence of the two highly-stressed areas in the outer sheet, which greatly decreased the integrity of the aged riveted lap joint due to the occurrence of the multiple-sited damages during cyclic loading.Peer reviewed: YesNRC publication: Ye