Issue 49

D. E. Belhadri et alii, Frattura ed Integrità Strutturale, 49 (2019) 599-613; DOI: 10.3221/IGF-ESIS.49.55

API 5L X65 properties [21]

Young’s modulus (GPa)

205 0.3 415

Poisson’s ratio

Minimum yield stress (MPa)

Yield strain

0.5%

Glass epoxy composite properties [22]

Young’s modulus E 1 Young’s modulus E 2 Poisson’s ratio υ 12 , υ 13 Poisson’s ratio υ 23 Shear modulus G 12 Shear modulus G 23

(GPa)

55

, E 3

(GPa)

15.2 0.254 0.428

, G 13

(GPa )

4.7

(GPa)

3.28

Adhesive (FM73) properties [23]

Young’s modulus (GPa)

3.28 0.45

Poisson’s ratio

Table 1: Material’s properties.

Figure. 3: Mesh type of the model and a geometry of the repaired pipe.

F INITE ELEMENT MODELING

T

he cracked pipe was modeled using ABAQUS 6.14 [24], and meshed using a structured mesh with three-dimensional hex-dominated quadratic elements with a focused mesh surrounding the crack-tip of 0.02 mm element [24, 25, 26, 27, 28]. A meshed pipe is shown in Fig. 3. The reduced, C3D20R integration elements are used in this modelization to compute the stress intensity factors. Only a quarter of the specimen was modeled due to symmetry conditions. The procedure used in the finite element analysis involved the following steps: (i) the internal pressure was applied to the

602