Issue 28

P.Valentino et alii, Frattura ed Integrità Strutturale, 28 (2014) 1-11; DOI: 10.3221/IGF-ESIS.28.01 3 The volume fraction of fibre has been evaluated by calculating the mass variation of a sample after heat treatment. In particular, a certain number of specimens, with plane dimensions of 20 x 10 mm, has been collected from the created panels, and each of them has been weighted by using a precision balance M ETTLER T OLEDO 204-S. A heat treatment, needed to completely burn the polymericmatrixwithout effecting the reinforcement [8-11], has been performed by using a Muffle furnace C ARBOLITE EML 11/6 for 15 minutes at 620 °C. After cooling, all the treated samples have been weighted again, therefore, the density of thematrix and fibres and, consequently, the fibre volume content, φ f , according to the standardDINEN 2559 [13], has been calculated as below: f f f f f c c m f c f f m m V V V V V m m m                   (1) where the subscripts f , m and c indicate the fibre, matrix and composite properties, respectively, V is the volume, m is the mass and  is the density. Figure 1 : Scheme of the layup used in the processing: 1 sealant tape, 2 vacuum connector, 3 release film, 4 peel ply, 5 composite layup, 6 peel ply, 7 perforated foil, 8 bleeder, 9 vacuum bag. Basalt fibres Epoxy resin Mechanical Property Value Mechanical Property Value Density,  2.75 g/cm 3 Density,  1.15 g/cm 3 Y OUNG ’smodulus, E 1 89GPa Y OUNG ’smodulus, E 2.65GPa Y OUNG ’smodulus, E 2 89GPa Shearmodulus, G 0.98GPa Shearmodulus, G 12 21.7GPa P OISSON ’s ratio, ν 0.35 Shearmodulus, G 23 21.7GPa P OISSON ’s ratio, ν 12 0.26 P OISSON ’s ratio, ν 23 0.26 Table 1 :Mechanical properties of basalt fibres [12] and epoxy resin [6]. Fabric type Yarn type Specificweight in g/m² Warp yarns per cm Fill yarns per cm Layup Layers Thickness inmm Fibre volume content f ρ in% Twill 2/2 Thread of direct roving 11.5 µm 110 tex 334 16 9 [0°/90°] 6 6 ~1,8 51.85 Twill 2/2 334 16 9 [90°/0°] 6 6 ~1,8 47.88 Twill 1/3 Direct roving 11.5 µm 110 tex 362 18 8 [0°/90°] 6 6 ~1,9 49.17 Twill 1/3 362 18 8 [90°/0°] 6 6 ~1,8 54.75 Table 2 : Types of fabrics, specificweights and layups.