Effect of modifying the thickness of the plate at the level of the overlap length in the presence of bonding defects on the strength of an adhesive joint

Attout Boualem, Sidi Mohamed Medjdoub, Madani Kouider, Kaddouri Nadia, Elajrami Mohamed, Belhouari Mohamed, Amin Houari, Salah Amroune and R.D.S.G. Campilho

Abstract

Adhesive bonding is currently widely used in many industrial fields, particularly in the aeronautics sector. Despite its advantages over mechanical joints such as riveting and welding, adhesive bonding is mostly used for secondary structures due to its low peel strength; especially if it is simultaneously exposed to temperature and humidity; and often presence of bonding defects. In fact, during joint preparation, several types of defects can be introduced into the adhesive layer such as air bubbles, cavities, or cracks, which induce stress concentrations potentially leading to premature failure. Indeed, the presence of defects in the adhesive joint has a significant effect on adhesive stresses, which emphasizes the need for a good surface treatment. The research in this field is aimed at minimizing the stresses in the adhesive joint at its free edges by geometric modifications of the ovelapping part and/or by changing the nature of the substrates. In this study, the finite element method is used to describe the mechanical behavior of bonded joints. Thus, a three-dimensional model is made to analyze the effect of defects in the adhesive joint at areas of high stress concentrations. The analysis consists of estimating the different stresses in an adhesive joint between two 2024-T3 aluminum plates. Two types of single lap joints (SLJ) were analyzed: a standard SLJ and another modified by removing 0.2 mm of material from the thickness of one plate along the overlap length, taking into account several factors such as the applied load, shape, size and position of the defect. The obtained results clearly show that the presence of a bonding defect significantly affects stresses in the adhesive joint, which become important if the joint is subjected to a higher applied load. On the other hand, the geometric modification made to the plate considerably reduces the various stresses in the adhesive joint even in the presence of a bonding defect.

Key Words

adhesive; bonding defect; modified lap joint; single lap joint; stresses

Address

Attout Boualem: Department of Mechanical Engineering, LMPM Laboratory, University of Djillali Liabes, Sidi Bel Abbes, Algeria Sidi Mohamed Medjdoub: Department of Mechanical Engineering, LMSS Laboratory, University of Djillali Liabes, Sidi Bel Abbes, Algeria Madani Kouider: Department of Mechanical Engineering, LMSS Laboratory, University of Djillali Liabes, Sidi Bel Abbes, Algeria Kaddouri Nadia: Department of Mechanical Engineering, LMSS Laboratory, University of Djillali Liabes, Sidi Bel Abbes, Algeria Elajrami Mohamed: Department of Mechanical Engineering, LMSS Laboratory, University of Djillali Liabes, Sidi Bel Abbes, Algeria Belhouari Mohamed: Department of Mechanical Engineering, LMSS Laboratory, University of Djillali Liabes, Sidi Bel Abbes, Algeria Amin Houari: Department of Mechanical Engineering, LMSS Laboratory, UMBB University Boumerdes, Algeria Salah Amroune: Department of Mechanical Engineering, M'sila University, Algeria R.D.S.G. Campilho: CIDEM, ISEP-School of Engineering, Polytechnic Institute of Porto, R. Dr. António Bernardino de Almeida, 431, 4200-072 Porto, Portugal; Institute of Science and Innovation in Mechanical and Industrial Engineering, Rua Dr. Roberto Frias, 400, 4200-465 Porto, Portugal

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