PSI - Issue 64

Yining Zhang et al. / Procedia Structural Integrity 64 (2024) 1334–1338 Y. Zhang and L. Hu/ Structural Integrity Procedia 00 (2019) 000 – 000

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The steel plates were welded using the gas metal arc welding (GMAW) method with a shielding gas mixture of 20% CO 2 and 80% Ar. The groove configuration (specified in AWS D1.1/D1.1M (2020)) and welding parameters, including welding current, welding voltage, and welding speed are given in Table 2.

Table 2. Groove configuration and welding parameters. Material Pass Current (A)

Voltage (V)

Welding speed (mm/min)

1

183

18.6

360

2

174

18.3

360

2.2. CFRP and adhesive

The CFRP sheet (HM-30, 300g/m 2 ) and the matching epoxy adhesive (HM-180C3P) used in this study were provided by Shanghai Horse Construction Co., Ltd. The mechanical properties, including f t , E , δ , and the thickness t of one layer are shown in Table 3.

Table 3. Mechanical properties of CFRP and adhesive. Material f t (MPa) E (GPa) δ (%)

t (mm)

CFRP

3667.5

240.0

1.8

0.167

Adhesive

59.6

4.6

1.7

0.500

3. Specimen The surface crack specimen was extracted from the butt-welded steel plate. The configuration of the unstrengthened and CFRP-strengthened specimen is shown in Fig. 2. The electric discharge method (EDM) was used to fabricate a semi-ellipse surface crack at the weld root. The crack has a depth of a =2mm and a width of c =4mm. To enhance the adhesion between CFRP and steel, the surface of the steel was sandblasted. One layer of CFRP was then bonded to both sides of the specimen. Note that the weld was preserved when applying CFRP, as removing the weld is difficult in some engineering cases.

Fig. 2. Un-strengthened and strengthened specimens.