Issue 48

M. Bezzerrouki et alii, Frattura ed Integrità Strutturale, 48 (2019) 491-502; DOI: 10.3221/IGF-ESIS.48.47 492 classifying different Materials used normalized specimen. The ASTM D1002 [2] is used for testing shear stress strength of adhesive for single lap joint made of two normalize plates adhesively bonded under tensile load. One presents here a brief outline of previous related works in the same domain. Goland and Reissner worked on the behavior of flexible adhesive using a normal stress [3]. Hart-Smith studied the shear and peel stresses distributions and gives a simplification for uncoupling shear and peel stresses [4]. He also developed solutions for stepping a single lap joint [5]. Bigwood and Crocombe [6] presented general elastic, shear and peel analysis for single lap joint using finite element analysis. Chiu and Jones [7] applied a finite element method to study a shear stress using a thick adherend test for a single and a symmetrical double lap joint . Pereira and Morais [8] conducted an experimental study using a double cantilever beam tests for single and double lap joints measured the critical strain energy-release rate and numerical one with finite element analysis using Abaqus code to explain a strength behavior and peel stresses at the edges of overlap area. Setoodeh, A. R and al. [9] used numerical and analytical methods for double lap joints to calculate peel stress using crack closure integral method and J- integral approach. Nunes, S.L.S and al. [10] a numerical analysis was used to compares the tensile performance of different chosen adhesives for single and double-lap joints by varying the overlap length to express normal and shear stresses over adhesive thickness and the cohesive zone modeling approach is introduced to estimate the joint strength. Recently, several studies have been made to try to reduce the stress concentration at the edges of the adhesive by the geometric modification of the edges of the plate by bevelling and or bead of the adhesive [11, 12] or by the combination of two modifications. Others have tried to improve the overlap length by geometrical modification for the adhesive and adherends edge such a waved, beveled or notched which presented a significant decrease in peel and shear stresses and ameliorate the quality and the durability of the structural adhesive joints [13], as well as the assembly of composite materials, attempts have been made to introduce hybrid composite materials and to change fiber orientations in the different adhesive layers. Madani, K. and al. [14] studies the effect of the geometry of the edge adhesive and adherend on reducing Von Mises, peel and shear stresses in the adhesive layer, several forms were considered namely bead of adhesive, internal and external beveling of the plate and the combination of an adhesive bead and beveling of the plate [15]. Our work fits in this context; the aim of this study is to improve the bonding techniques by introducing geometric modifications on ASTM-D1002 single-lap-joint making with 2024-T3 Aluminum specimens bonded with ADEKIT A- 140 adhesive. Two modifications are made to the single-lap-joint ASTM-D1002, the first is a reduction of thicknesses of plates along overlap length and the second one is to apply a reduction for only one plate for the assembly. The specimens were simulated numerically by the three-dimensional finite element method using the ABAQUS calculation software. The results clearly show that these two modifications bring about a considerable reduction of the stresses at the edge and the depth of the adhesive. G EOMETRICAL MODEL AND MECHANICAL PROPERTIES ne considers an assembly of two 2024-T3 Aluminum plates bonded with ADEKIT A-140 adhesive. The basic geometric model is the ASTM D1002 single-lap-joint. The dimensions of the different substrates of the ASTM D1002 single-lap-joint without modification are shown in Fig. 1 and it is called in this paper: Model 1. The fixations localized are gives at grips areas and the stress are applied at one side along X axis using variable values. Figure 1: Basic geometrical model ASTM D1002 (Model 1). O mm Grip area Grip area Overlap area Lo=12.7 63.5 mm 190.5 mm 139.7 mm 25 4 mm 25.4 mm 63.5 mm 25.4 mm Overlap area 2 mm 0.2 mm 2 mm σ X Y Z