Local evaluation of adhesive failure in similar and dissimilar single-lap joints Florin Adrian Stuparu a , Dragos Alexandru Apostol a , Dan Mihai Constantinescu a,⇑ , Catalin R. Picu a,b , Marin Sandu a , Stefan Sorohan a a University POLITEHNICA of Bucharest, 060042 Bucharest, Romania b Rensselaer Polytechnic Institute, 12180 Troy, NY, USA article info Article history: Received 7 January 2017 Received in revised form 19 May 2017 Accepted 20 May 2017 Available online xxxx Keywords: Single-lap joint Digital image correlation Cohesive zone model Aluminium and carbon adherends abstract Single-lap joints made of aluminium and carbon fibre adherends are tested to understand better the behaviour of such dissimilar joints. Local deformation fields are monitored by using the digital image correlation method (DIC). Over the overlap length strain gauges are emulated as to measure properly the strains in the adhesive. Peeling and shearing strains are investigated, emphasizing that peeling is important in the region where failure is initiated, towards the extremity of the overlap region. Cohesive Zone Modelling (CZM) available in Abaqus Ò was used to simulate the behaviour and strength of dissimilar single-lap adhesively bonded joints. A linear elastic FEM was used. A distinct CZM model is used to show the variation of normalized stresses and damage in the process zone of the single-lap joint. Experiments show that the use of dissimilar aluminium-carbon and carbon-carbon adherends is reducing the strength and stiffness of the joints as the delamination and pull-out of the carbon fibres compromises their integrity. Numerical simulations overestimate the experimental strength and stiffness of the joints. FEM model has to be improved as to consider a refined laminate modelling. Ó 2017 Elsevier Ltd. All rights reserved. 1. Introduction In engineering structural integrity applications the presence of imperfections can reduce significantly the load bearing capacity. Without a better understanding of progressive failure, the fracture criteria and predictive capabilities will be lim- ited. Interface cracking is generally a mixed mode cracking, as both normal and shear stresses develop ahead of the crack tip even when the interface crack is loaded in pure Mode I, [1,2]. Experiments have shown that fracture energy can depend on mode mixity, [3–5]. A comprehensive literature review on the types of tests used for adhesive joints for single and mixed- mode fracture, underlining their advantages and disadvantages, was done by Chavez et al. [6]. They concluded that there is no general agreement about the test suitability for mixed-mode fracture assessment of adhesive joints. During the crack growth process, two new surfaces are created. Before the physical crack is formed, these two surfaces are held together by traction within a cohesive zone. The traction varies in relation to the relative displacement of the surfaces, and a cohesive law describes the phenomena in the cohesive zone in terms of the traction and the separation of the surfaces to be formed during fracture. A cohesive law is also denoted as a traction-separation law. The concept to describe the http://dx.doi.org/10.1016/j.engfracmech.2017.05.029 0013-7944/Ó 2017 Elsevier Ltd. All rights reserved. ⇑ Corresponding author at: Department of Strength of Materials, University POLITEHNICA of Bucharest, 060042 Bucharest, Romania. E-mail address: dan.constantinescu@upb.ro (D.M. Constantinescu). Engineering Fracture Mechanics xxx (2017) xxx–xxx Contents lists available at ScienceDirect Engineering Fracture Mechanics journal homepage: www.elsevier.com/locate/engfracmech Please cite this article in press as: Stuparu FA et al. Local evaluation of adhesive failure in similar and dissimilar single-lap joints. Engng Fract Mech (2017), http://dx.doi.org/10.1016/j.engfracmech.2017.05.029