PSI - Issue 22

Lunwen Guo et al. / Procedia Structural Integrity 22 (2019) 194–200 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

198

5

(a)

(b)

Fig. 4. The failure images: (a) scaled double-layer steel pipes and (b) scaled CFRP-steel pipes

Table 1. The results of tensile test

Fillet radius /mm

Average tensile limit load/N

The winded filament number on single pin

Load require: yes or no

Specimens

204000 226000 240000

15 18 21

no

CFRP-steel pipe Double-layer steel pipe

9

yes yes

—

230000

—

yes

The results of tensile test indicated that the load capacity improved with the increasing of the winded filament number on single pin. The maximum loads can be up to 21T while the fillet radius was 9mm and the winded filament number was 18 bundles. In addition, it implied that this flange structure can reach the required tensile load. 4. The manufacture and test of CFRP-steel pipe 4.1. Winding process The explosion-proof outer layer and the stress sharing inner layer were winded with an angle at 90°, and the middle layer was winded with a small angle at 17°. The winding of the middle connecting layer is the most difficult in the whole winding process. According to the filament winding process, it is unable to build the winding model of pins with the present software. But the flange pins can be equivalent to a very large friction coefficient based on equivalent principle on the winding software, and the winding patterns simulation of filament winding on pins can be realized indirectly. The process of filament winding patterns simulation and the winding process of the middle layer are shown in Fig. 5.

(a)

(b)

Fig. 5. (a) The patterns simulation of filament winding on pins; (b) The winding process of the middle layer

From the tensile test of the above- mentioned scaled specimens, it’s shown that when the pin radius was 9 mm, the winding angle was 17°, the winded filament number on single pin were 18 bundles, and the carbon fiber prestress of single bundle of was 35 MPa, the connection structure can meet the requirements of axial tensile load. The test results