PSI - Issue 14

Sanjeev M Kavale et al. / Procedia Structural Integrity 14 (2019) 584–596 Sanjeev M. Kavale, Krishnaraja G Kodancha, Nagaraj Ekbote / Structural Integrity Procedia 00 (2018) 000–000

587

4

corresponding nodes are given displacement boundary conditions of U y = U z = U Rx = U Ry = 0. Similarly for CT specimen, the load applied at the pin holes is simulated by applying point loads on the circumference of the pin hole, which approximately subtends 120 0 angle. The nodes of loading pins holes are given displacement boundary conditions having U x = U z = 0 and U y ≠ 0 to keep the loading in mode-I. 3D linear elastic FE analyses have been conducted on specimens of thickness 3mm, 5mm, 10mm, 12.7mm, 15mm and 25.4mm. The SIF is extracted for various cases by using J based method built in ABAQUS directly from the software. This is based on the integration integral method in which stress intensity factors are directly obtained as indicated by Gosz et al. (1998). The magnitude of the applied stress σ is calculated using Eq. 2 for SENB specimen. The same is used by Kudari and Kodancha (2014). Equation 3, which is suggested by Priest (1975) is used for finding the magnitude of applied stress for CT specimen. The same has been used by Kodancha and Kudari (2017). The analyses are performed for the applied stress σ = 100MPa to keep the analysis in linear elastic fracture mechanics conditions.

  2 2 3 B W PS

 

(2)

 2 2



  2 BW P W a 

 

(3)

3. Results and Discussions

0.7 (B)

1000 (A)

0.6

950

CT, Plane Stress CT, Plane Strain

0.5

900

SENB, Plane Stress SENB Plane Strain SENB, Analytical Value

1/2

0.4

a/W=0.50

850

T 11 / 

CT, Plane Strain CT, Plane Stress

0.3

a/W=0.50

800

CT, Analytical Value SENB, Plane Strain SENB, Plane Stress SENB, Analytical Value

0.2

K I in MPa(mm)

750

0.1

700

0.0

0.20 0.25 0.30 0.35 0.40 0.45

0.20 0.25 0.30 0.35 0.40 0.45

Poisson's ratio

Poisson's ratio

Fig. 2 2D Variation of (A). K I and (B). T 11 for SENB and CT specimen for a/W =0.50 and different Poisson’s ratio.

The magnitudes of Stress Intensity Factor obtained for 2D analyses are validated with the analytical values available in literature (Anderson (2004)). 2D K I magnitudes for a/W = 0.50 ratios under plane strain and plane stress conditions for SENB and CT specimen with analytical values are indicated in Fig. 2(A). The error between analytical and FE values in the magnitude of K I is 3.2% and 0.7% for CT and SENB specimen respectively. Also it can be noted that there is no variation in the magnitude of SIF with variation of Poisson’s ratio for 2D specimen for both plane stress and plane strain conditions. On the similar lines, variation in normalized T 11 -Stress ( T 11 / σ ) is also studied and shown in Fig. 2(B). The values of T 11 are validated with the formulation made ready by Sherry et al. (1995) for SENB specimen. An error of 7.6% is observed between Analytical and FE values. The validation of T 11 for CT specimen wasn’t possible since no literature was found as per the best knowledge of authors on estimating T 11 for latest geometry of CT specimen mentioned in ASTM standard. However, the estimation of SIF was satisfactory and method of estimation of T 11 is same as SENB. It could be noted that there is no variation in T 11 -