Improvement of the mode II interface fracture toughness of glass fiber reinforced plastics/aluminum laminates through vapor grown carbon fiber interleaves

Figures & data

Table 1 Physical and mechanical properties of GFRP prepregs, A2017 and VGCF.

GFRP prepreg			VGCF
Young’s modulus (fiber direction)	48 GPa	Diameter	150 nm
Young’s modulus	5 GPa	Length	10–20 μm
Glass fiber	65%	Aspect ratio	10–500
A2017		Density	2.0 g cm^−3
Young’s modulus	72 GPa	Young’s modulus	273–760 GPa
Tensile strength	375 MPa	Tensile stress	2700–3500 MPa

Figure 1 Schematic illustration of the specimen fabrication process.

Figure 2 Surface morphology of the aluminum layers. (a) Before acid etching treatment; (b) after acid etching treatment.

Figure 3 Specimen for ENF tests (length U = 140 mm; width B = 20 mm; height H = 4.34 mm; L = 50 mm; initial crack length a = 40 mm).

Figure 4 Typical load-displacement curves for all kinds of (a) 0° GFRP/Al laminates; (b) 90° GFRP/Al laminates.

Figure 5 Critical loads of various GFRP/Al laminates.

Figure 6 Fracture toughness at crack growth for various GFRP/Al laminates.

Figure 7 Increasing ratios of critical load and fracture toughness for all kinds of specimens. (Increasing ratio: (P_Increased−P_Plain)/P _Plain, ‘P’ denotes G_IIC or critical load, ‘Increased’ denotes samples of acid treatment or VGCF addition, and ‘Plain’ denotes pristine samples.)

Figure 8 Difference ratios of critical load and fracture toughness of 90° specimens compared to 0° specimens. (Difference ratio: (P₉₀°−P₀°)/P₀°, ‘P’ denotes G _IIC or critical load, ‘90°’ denotes 90° samples, and ‘0°’ denotes 0° samples.)

Table 2 Material properties of cohesive element.

Specimen	K (GPa mm^−1)	G IIC (J m^−2)	N (MPa)
Plain-0°	200	155.1	15
Plain-90°	200	149.7	15
A-V10-0°	250	572.6	30
A-V10-90°	250	711.0	30

Figure 9 Numerical and experimental load-displacement curves for (a) Plain-0° and V10-0° specimens; (b) Plain-90° and V10-90° specimens.

Figure 10 Crack propagation of all kinds of GFRP/Al laminates (a) Plain; (b) V10; (c) A-V0; (d) A-V10; (e) V20; (f) A-V30.

Figure 11 Fracture surface observation of all kinds of GFRP/Al laminates (a) Plain; (b) V10; (c) A-V0; (d) A-V10; (e) A-V20; (f) A-V30.

Figure 12 SEM images of fracture surface (a) A-V10; (b) A-V20; (c) A-V30.

Figure 13 VGCF dispersion condition (a) A-V10; (b) A-V20; (c) A-V30.

Figure 14 Schematic illustration of the toughening mechanism of the rolling stripes.