Consideration on the strength improvement of stepped-lap joint based on the analysis of singular stress field

Abstract

The stepped lap joint has intermediate properties of butt joints and lap joints. By changing the step number Ns, it is possible to simulate the unevenness of the bonding interface to improve the adhesive strength. In this paper, the intensity of a singular stress field (ISSF) is focused, and the effect of Ns on the adhesive strength is investigated in terms of the ISSF. Two models are considered. One is the model to analyze the ISSF at the end of the stepped joint. The other is the model to investigate the ISSF at the first corner of the bonded interface when the first step is broken. The adhesive strength mechanism is studied in terms of those ISSFs values under the σ_x^∞ and σ_x^∞ = σ_c^Initial applied and also under the crack initiation load is applied.