Issue 45

C. Bellini et alii, Frattura ed Integrità Strutturale, 45(2018) 173-182; DOI: 10.3221/IGF-ESIS.45.15 175 M ATERIALS AND METHODS ingle lap joints were obtained from two laminates measuring 25.4mm x 101.6mm x 2.5mm while, in order to have a square bonding area, the overlap length was placed at 25.4mm. All the specimens are realized according to ASTM D5868 and ASTM D1002. The nominal thickness of the adhesive was set equal to 0.76mm (Fig. 1). Figure 1 : Measures of a single lap joint specimen. A prepreg produced by SAATI S.p.A., made of ER450 epoxy resin and CC289 carbon fibres with 5H satin weave, was used for the realization of the adherends. The layup used was [(0°, 90°)] 8 , where (0°, 90°) is one layer of fabric. The treatment process consists of a ramp of 2°C/min. for 55min. and in maintenance at 135 ° C for 2 hours at a pressure of seven bar. The peel ply used is 51789 produced by Precision Fabric Group, made of nylon fibres woven together. The operations carried out to obtain the surface finish simply consist of inserting it at the end of stratification on the laminate and removing it at the end of the polymerization just before the bonding phase. The adhesives identified to perform the tests are the EA 9309NA paste adhesive produced by Hysol and the AF 163-2K film adhesive produced by 3M Scotch-Weld. The general characteristics of the adhesives are reported in Tab. 1. Type Shear Strength [MPa] ASTM D1002 Poisson’s Coefficient Tensile Strength (25°C) [MPa] ASTM D638 Tensile Modulus (25°C) [MPa] ASTM D638 T g (Dry) [°C] AF 163-2K Film 39.9 0.34 48.26 1103.2 108 EA 9309NA Paste 34.5 0.35 37.90 2067.0 59 Table 1 : Properties of the adhesives . Figure 2 : CAD of the mold used to realize SLJ specimens. The Hysol EA 9309NA is a two-component paste adhesive, composed of a translucent beige paste (part A) and a red activator (part B), to be mixed according to the weight ratio of respectively 100 (part A) and 23 (part B). For this adhesive, the polymerization reaction takes place at room temperature for 7 days. S