Materials

The material used in this study consists of 2400 Tex E-glass fibres impregnated with an epoxy matrix. The resin is an EPOLAM pre-polymer, EPOLAM 2020 hardener and 2020 accelerator from Axson. Glass fibres are commonly used for naval applications because of their high strength/mass ratio and their low cost compared to other reinforcements. The reinforcement consists of a plain weave fabric with 90% warp yarns and 10% weft yarns. Panels are made by an infusion process and seven orientations are studied: 0°, ±20°, ±30°, ±45°, ±60°, ±70° and 90°. The square panels, 500×500 mm, were cut into cubic samples of the geometry dimensions as shown in Table 1. The standard deviations are indicated in brackets.

Panel

Thickness,

(mm)

Surface

(mm2)

Void fraction (%)

Stacking

sequence

Fibre volume Fraction (%)

A

13.00 (0.1)

13×13 (0.2)

2.26

[0]40

53.5 (0.5)

B

12.52 (0.3)

13×13 (0.2)

2.00

[±20]20

54.0 (0.5)

C

13.00 (0.1)

13×13 (0.2)

1.78

[±30]20

55.0 (0.5)

D

12.78 (0.2)

13×13 (0.2)

1.69

[±45]20

54.3 (0.5)

Table 1. Geometry and fibre mass fraction of the samples, standard deviation in brackets

Two types of static compression tests are used to obtain the elastic properties of the lamina. In-plane loading (IP), parallel to the plies plane; plane (1,2), and out-of-plane loading (OP), according to the thickness; direction 3 (Figure 1). Table 2 compares the elastic values of the characteristics drawn from relations of micromechanics (Chamis, 1984) with those resulting from experimental work.

Characteristics

E1 (MPa)

E2 (MPa)

E3 (MPa)

V12

V13

V 23

G12 (MPa)

G13 (MPa)

G23 (MPa)

Experimental

46217

16086

9062

0.28

0.41

0.097

2224

3500

4540

Rules law

42030

14524

9130

0.31

0.01

3441

3273

4508

Table 2. Elastic properties of E-glass/epoxy lamina

1} mm

Materials

Fig. 1. Sample loadings and coordinates of axis