Dynamic deformation of lap joints and scarf joints under impact loads

The propagation of stress waves and the concentration of dynamic stress und er impact loading in single lap joints, tapered lap joints and scarf joints , which were bonded adhesively, were investigated analytically and experime ntally Viscoelastic properties of cured adhesive resin were obtained from t he variation of strain waves which propagated in a rod of cured resin. The compliance of the cured adhesive resin depended on the frequency of the str ain waves. The viscoelastic properties obtained in the test were formulated by Voigt viscoelastic models. The stress distribution and the time variati on of stress and strain in the joints under tensile impact loading were cal culated using the finite element method, considering the viscoelastic prope rties of the adhesive. Stress concentration occurred in both the edges of t he adhesive layers of the single lap joints and the tapered lap joints. The stress concentration in the scarf joints was relatively small. The stress occurred in the taper lap joints was smaller than that in the single lap jo ints when the taper lap joints had enough taper length. Impact test on the joints, which had adherends of aluminum alloy, was conducted to verify the pertinence of the analyses. The deformation of the tapered lap joints and t he scarf joints showed good agreement on the analytical results. The deform ation of the single lap joints was more complicated than the analytical res ults. (C) 2000 Elsevier Science Ltd. All rights reserved.