PSI - Issue 14

Ritu. J. Singh et al. / Procedia Structural Integrity 14 (2019) 549–555

552

4

Ritu .J. Singh/ Structural Integrity Procedia 00 (2018) 000–000

� � � �����������

���� � � � � � �� � � � �� � � � � � � � � �

(1)

a

b

Hoop Stress Radial Stress Von Mises Stress

Hoop Stress Radial Stress Von Mises Stress

100 200 300 400 500 600 Stress, MPa

100 200 300 400 500 600

Stress, MPa

-200 -100 0

-200 -100 0

Isotropic case

Anisotropic case

0

20 40 60 80 100

0

20 40 60 80 100

Distance from inner surface, %

Distance from inner surface, %

Fig. 2. Modelling results of stresses along thickness of cylinder for (a) isotropic and (b) anisotropic material properties

3. Results and Discussions The radial, transverse and von mises stresses along the thickness of cylinder subjected to maximum pressure at which yield initiates at inner surface is shown in Fig. 2. The elastic solution for isotropic and anisotropic material model matches well. This is owing to the fact that elastic anisotropy is not affecting the solution as the difference in the values of elastic constants in each direction is not substantial. The applied internal pressure is ~195MPa which is fixed based on equation 1. The von mises stress at the inner surface reaches ~ 625 MPa indicating that inner surface will begin to yield for the isotropic material model. However as it will be discussed further, the yielding will not initiate for anisotropic case. As the internal pressure increases, plastic deformation starts from inner surface of the cylinder and continues to extend towards outer surface. Stress distribution along the thickness is obtained by increasing the internal pressure by 10% - 60% of the internal pressure at which yielding initiates. The stress distribution (von mises stress, stress hoop and radial stress) in a cylinder subjected

a

b

1100

800

elastic pw1-1 pw1-2 pw1-4 pw1-6 pw1-7

1000

700

900

800

600

700

500

600

Elastic pw1-1 pw1-2 pw1-4 pw1-6 Isotropic material model

Von Mises Stress (MPa)

500

400

Von Mises Stress, MPa

400

300

Anisotropic material model

300

0

20

40

60

80

100

0

20

40

60

80

100

Distance from inner surface (%)

Distance from inner surface, %

Fig. 3.von mises stress distribution (a) isotropic (b) anisotropic material properties

to different internal pressure for isotropic and anisotropic material model is shown in Fig. 3&4. It is observed from the von mises