Issue 49

R. Marat-Mendes et alii, Frattura ed Integrità Strutturale, 49 (2019) 568-585; DOI: 10.3221/IGF-ESIS.49.53

(a)

(b)

Figure 1: Manufacturing of the sandwiches with: (a) aluminum skins; (b) BFRP skins.

Polyurethane core BFRP [(0/90)/(45/-45)] s

lay-up

Peel-ply Felt Teflon film Vacuum sealant Steel plate

(a)

(b)

Figure 2: Manufacturing of the SB sandwich composites: (a) Stacking sequence before vacuum bagging; (b) Vacuum bag.

Density [kg/m 3 ]

E 11

=E 22

E 33 [GPa]

G 12

= G 13

= G 23

Thickness [mm]

 

= 

 

[GPa]

[GPa]

BFRP composite

1538

16

3.2

0.33

0.35

2.7

h f

= 1

Table 2: BFRP Properties. (1, 2, 3 refers to longitudinal, transversal and across the thickness of the specimens, respectively)

P

P

(a)

(b)

a=L/2

a=L/2

h c +2h f

h c +2h f

h c

h c

L=90 or 136mm 390 mm

L=250 or 340mm 390 mm

P/2

P/2

P/2

P/2

(c)

(d)

a=L/4

a=L/3

h c +2h f

h c +2h f

h c

h c

L=90 or 136mm

L=250 or 340mm 390 mm

390 mm

Figure 3: Schematic diagram of the test field configuration for the specimens’ with: (a) 3PB short-beam; (b) 3PB long-beam; (c) 4PB short-beam; (d) 4PB long-beam. (all specimens have the same width, b =70mm, perpendicular to the paper)

Mechanical Testing Mechanical tests were undertaken in an Instron3369 universal test machine equipped with a 10 kN load cell. Three-point bending (3PB) and four-point bending (4PB) flexural tests were conducted in conformity to ASTMC393 [7] with a crosshead rate of 2 mm/min. Prior to mechanical tests, strain gages were glued to the surfaces of the 3PB (bottom) and 4PB (top and bottom) specimens in order to obtain the strains in the sandwich composite faces.

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