Issue 28

P.Valentino et alii, Frattura ed Integrità Strutturale, 28 (2014) 1-11; DOI: 10.3221/IGF-ESIS.28.01

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:

m

f

f V V V V V m m m       f f

f 

(1)

 

c

c

m

f

c

f

 

  

 

f 



m

where the subscripts f , m and c indicate the fibre, matrix and composite properties, respectively, V mass and  is the density.

m is the

is the volume,

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

2.75 g/cm 3

1.15 g/cm 3 2.65GPa 0.98GPa

Density, 

Density, 

Y OUNG ’smodulus, E 1 Y OUNG ’smodulus, E 2 Shearmodulus, G 12 Shearmodulus, G 23 P OISSON ’s ratio, ν 12 P OISSON ’s ratio, ν 23

Y OUNG ’smodulus, E

89GPa 89GPa

Shearmodulus, G P OISSON ’s ratio, ν

21.7GPa 21.7GPa

0.35

0.26

0.26 Table 1 :Mechanical properties of basalt fibres [12] and epoxy resin [6].

Fibre volume content f ρ in% 51.85

Fabric type

Warp yarns per cm

Fill yarns per cm

Yarn type Specificweight in g/m²

Layup

Layers Thickness inmm

Thread of direct roving 11.5 µm 110 tex

Twill 2/2

334

16

9

[0°/90°] 6

6

~1,8

6

~1,8

47.88

Twill 2/2

334

16

9

[90°/0°] 6

Twill 1/3 Direct roving 11.5 µm 110 tex Twill 1/3

362 362

18 18

8 8

[0°/90°] 6 [90°/0°] 6

6 6

~1,9 ~1,8

49.17 54.75

Table 2 : Types of fabrics, specificweights and layups.

3