Issue 45

C. Bellini et alii, Frattura ed Integrità Strutturale, 45(2018) 173-182; DOI: 10.3221/IGF-ESIS.45.15 173 Influence of hydrothermal ageing on single lap bonded CFRP joints Costanzo Bellini, Gianluca Parodo, Wilma Polini, Luca Sorrentino University of Cassino and Southern Lazio, Cassino (FR), Italy gianluca.parodo@unicas.it A BSTRACT . Nowadays adhesives are widely used in structural applications, in particular for assembly composite materials. In fact, this technique allows to obtain a more uniform load in the joint, to realize a joint with a higher specific strength and to avoid drilling parts as in the case of bolted joints. However, the mechanical properties of bonded parts over time are not well understood if they are subjected to a more or less aggressive environment. Generally, the main factors of influence regarding the durability of bonded joints are humidity and temperature, but their effects are not always clear if these two factors act simultaneously. In this work the effect of hydrothermal ageing on the mechanical resistance of single lap bonded CFRP joints has been investigated. In particular two types of adhesives (AF 163-2K film and EA 9309NA paste) and three ageing environments (thermal cycles from -28 °C to 85 °C in air, distilled water and salt water) have been chosen for the activity. K EYWORDS . Hydrothermal ageing; Adhesive bonding; Single lap joint; Experimental tests. Citation: Bellini, C., Parodo, G., Polini, W., Sorrentino, L., Influence of hydrothermal ageing on single lap bonded CFRP joints, Frattura ed Integrità Strutturale, 45 (2018) 173-182. Received: 02.06.2018 Accepted: 23.06.2018 Published: 01.07.2018 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. I NTRODUCTION n the last decades, there has been an increasing use of composite materials in structural applications. This has entailed greater attentions from the designers regarding the stability of the composite structures in the medium-long term, in particular on the weak points of the structures, namely in the junctions between the components of the assembly. The composite parts can be assembled using rivets or bolts, or adhesives or, in the most complex joints, through a combination of both. Compared to traditional fastening systems, the use of structural adhesives allows to obtain a series of advantages such as the reduction of the weight of the joints, the elimination of corrosive problems typical of metal rivets and bolts and the reduction of the local delamination of the parts due to drilling, as noted by Sorrentino et al. [1,2]. However, nowadays their use is limited by the incomplete knowledge of how they can behave over time in contact with more or less aggressive environments. For example in the case of epoxy adhesives, it is known that the factors of influence of the stability of the joint over time are mainly the temperature and humidity, but in most cases, it is impossible to estimate their effect on the durability of the joint except by experiments. In fact, it is difficult to reach definitive conclusions because of the various possible combinations adherend/adhesive. The knowledge of the behavior of the individual adherend and adhesive is not a sufficient condition to estimate the strength of the assembled joint. An example is the case of hybrid composite-metal coupling, which can lead to corrosion phenomena. In seawater, the galvanic coupling due to the different nature of the I