Issue 46

A. Akhavan-Safar et alii, Frattura ed Integrità Strutturale, 46 (2018) 266-274; DOI: 10.3221/IGF-ESIS.46.24 272 Figure 10 : Different failure phenomena caused by cork particles. Figure 11 : Crack initiation and propagation between two adjacent cork particles. Fig. (10) shows two aggregated particles. Cork agglomeration increases the stress concentration areas and subsequently decreases the joint strength. Higher cork density also causes a decrease of the adhesive thickness between two adjacent particles, which results in the weakening of the bonding strength between them. In this condition, crack bridging (initiation and propagation of crack between two particles) takes place quickly between the neighbour corks (see Fig. (11)) which leads to cork coalescence and creating a larger damaged area inside the specimen. Considering the present results, it can be concluded that there is an optimum amount of cork corresponding to the best adhesive fracture toughness and highest joint strength. The trend presented by the bulk results (Fig. (7)) is different from that shown by the SLJs results (Fig. (9)). It is mainly because the bulk specimens are loaded in tension and the SLJs are