Residual Stress/Strain in Three-Row, Countersunk, Riveted Lap Joints

Abstract

The stress/strain variations from the riveting process to the tensile loading stage in lap joints with three-row countersunk rivets were studied experimentally and numerically. Three different forces were used in the riveting process. After releasing the rivet squeeze forces, the lap joints were then loaded in tension. Three-dimensional finite element models were developed to simulate the experimental setup. The material elasto-plastic constitutive relationship and geometric non-linear properties, as well as, nonlinear contact boundary conditions were included in the numerical simulations. The numerical modeling techniques were validated using experimental data. The effect of the residual stress on the stress variations, along a prescribed path during the tensile loading stage, is discussed. Full-field contours of the residual minimum principal stress induced by the riveting process, and the maximum principal stress during the tensile loading stage are also analyzed. The aim of this research is to develop an accurate three-dimensional numerical technique to study the complex stress and strain distributions induced by the entire loading sequence, and to use this information to more accurately predict the fatigue life of fuselage lap joints.