Issue 35

S. Xinhong et alii, Frattura ed Integrità Strutturale, 35 (2016) 441-448; DOI: 10.3221/IGF-ESIS.35.50

direction of the specimen and the direction normal to the crack initiation and early propagation plane is defined as critical plane orientation, φ , which is shown in Fig. 2, where the origin O of the coordinate system is at the surface of the minimum diameter dimension of specimen, the x direction is the longitudinal direction of the specimen and the y direction is the direction circumferential to the surface of the specimen.

Figure 2 : Definition of the crack initiation and early propagation plane orientation 

The crack path under different mean stress is shown in Fig.3. The position of the crack initiation and early propagation plane orientation is marked in the figure.

X

X

,  x m

,  x a

,  x m

,  x a

(a)

=0MPa,

=185 MPa

(b)

= 50MPa,

=185 MPa

X

X

,  x m

,  x a

,  x m

,  x a

(c)

= 100MPa,

=180 MPa

(d)

= 150MPa,

=140 MPa

Figure 3 : crack path under different mean stress.

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