Investigation of Analytical Modeling for Structural Damping Properties in Riveted Lap Joints

Abstract

Riveted lap joints are widely used to assemble aircraft structures. It is well known that structural joints have a significant role to characterize static and fatigue strength, damage tolerance, stiffness, vibration and structural damping. From a structural dynamics analysis point of view, it is needed to determine structural damping characteristics of airframe carefully for evaluating structural dynamics behaviors. Regarding a fatigue evaluation of aircraft structures, “mechanical joint” is one of the important areas where a structural monitoring should be applied during all life of aircraft. In order to establish a method to estimate structural damping characteristics and to characterize degradation and damages inside a mechanical joint from the information of structural damping, the new analytical model which can express structural damping characteristics of riveted lap joints was proposed. The equations for the displacement as the function of tensile load are established as a new analytical model for riveted single lap joint. Using a data of the force/displacement hysteresis loops from cyclic loading tests with riveted single lap joint specimens, unknown coefficients of the new analytical model can be identified. As the results, it is verified that this model can express force/displacement hysteresis loops very well and be used for characterizing structural damping properties of rivet joints. Using the results from finite element analyses and the load-deflection hysteresis loops from cyclic loading tests with additional specimens, assumptions to establish the new analysis model are verified.