Issue 46

A. Akhavan-Safar et alii, Frattura ed Integrità Strutturale, 46 (2018) 266-274; DOI: 10.3221/IGF-ESIS.46.24 266 Micro failure analysis of adhesively bonded joints enhanced with natural cork particles: Impact of overlap length and particles volume fraction Alireza Akhavan-Safar Fatigue and Fracture Laboratory, School of Mechanical Engineering, Iran University of Science and Technology, 16846-13114, Tehran, Iran. Akhavan_Safar@iust.ac.ir Ana Queirós Barbosa INEGI, Rua Dr. Roberto Frias,400 4200-465, Porto, Portugal. aqueiros@inegi.up.pt Lucas Filipe Martins da Silva Department of Mechanical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal Lucas@fe.up.pt Majid Reza Ayatollahi Fatigue and Fracture Laboratory, School of Mechanical Engineering, Iran University of Science and Technology, 16846-13114, Tehran, Iran. m.ayat@iust.ac.ir A BSTRACT . In this work, the effects of natural particles on the micro failure mechanisms and static strength of an epoxy are studied using scanning electron microscope (SEM) technique. To this end, bulk specimens and adhesively bonded single lap joints (SLJs) containing different amount of micro cork particles were fabricated and tested. To investigate the toughening mechanisms, the fracture surfaces of the specimens were analyzed using SEM and a magnifying glass. It was shown that the deviation of the crack path and formation of micro-cracks generate multi fracture surfaces which is one of the main sources of energy absorption and resulted in higher fracture energy of the enhanced adhesives. Corks also acts as a crack stopper, stabilizes the crack propagation and prevents unstable crack growth. However, the micro analysis showed that higher contents of cork lead to agglomeration of the particles which acts as a source of stress concentration, with a higher possibility of delamination between the matrix and the micro corks. Accordingly, there is an optimum amount of cork where the best adhesive fracture toughness is reached. The results showed that the optimum value of micro particles depends on the loading conditions. Citation: Akhavan-Safar, A., Ayatollahi, M.R., Queiros Barbosa, A., da Silva, L.F.M., Micro failure analysis of adhesively bonded joints enhanced with natural cork particles: Impact of overlap length and particles volume fraction, Frattura ed Integrità Strutturale, 46 (2018) 266-274. Received: 20.05.2018 Accepted: 15.08.2018 Published: 01.10.2018 Copyright: © 2018 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.