Issue 45

C. Bellini et alii, Frattura ed Integrità Strutturale, 45(2018) 173-182; DOI: 10.3221/IGF-ESIS.45.15 176 The AF 163-2K is a film adhesive with a thickness of about 0.24mm and has a carrier inside which gives it greater tensile strength. The polymerization reaction occurs in an autoclave according to the technical data sheet. In order to guarantee the final geometry of the joints, specific equipment for the bonding was used (Fig.2). In total, 18 specimens were made, which were divided into 6 lots respectively, each consisting of 3 specimens. The 6 lots were randomly divided into three groups, so that each group has the same number of joints made with AF 163-2K and EA 9309NA. Subsequently, the created groups, made up of six specimens each, were subject to different cyclical conditions of ageing (Tab. 2). Factors # Level Levels Adhesive 2 AF 163-2K, EA 9309NA Ageing conditions 3 Distilled water, salt water, air Replications 3 Table 2 : Experimental Plan. To realize the ageing treatments, it has been used a model 125/45HA oven manufactured by Nabertherm GmbH, equipped with a convection chamber; and a 2700 model multimeter manufactured by Keithley Instruments, combined with the use of K-type thermocouples for temperature control during the process; The specimens relative to the first group were subjected to a daily cycle of 4 hours at 85 ° C and about 20 hours at -28 ° C. The specimens of the second group were immersed in distilled water. In order to avoid evaporation of the water, which would cause the rise of the specimens from the water itself, the container was closed with a nylon film called elastomax produced by Aerovac Systems Ltd. The specimens relating to the third group underwent the same process applied to the second group, using salt water instead of distilled water. The saline solution was made according to ASTM D1183. The latter groups were subjected to a daily freezing cycle at -28°C for 16 hours and thawing and maintaining at 85°C for 6 hours. The remaining 2 hours were used to cool the containers to an acceptable temperature in order to place them in the climatic chamber. At the end of each cycle, a check on the water level in the containers was performed and, where necessary, a top- up was carried out. In order to monitor the temperature, a laminate of the same thickness of the adherends was inserted into each group with a K-type thermocouple inside. All three groups have undergone the above-mentioned cycles for thirty days. Figure 3 : Ageing cycles measured with K-thermocouple.