Analysis of Interacting Semi-elliptical Cracks in Plate and Thick Walled Cylinders for Linear Elastic and Elastic Plastic Regime Using FEM

Yugal Kishor Sahu,Dr. Shubrata Nagpal

The methodology used for assessing the structural integrity of a given material plays as crucial role in predicting the stress intensity factor (SIF) arises between neighbouring cracks. In this research a MATLAB extended finite element Method (XFEM) has been applied to determine interaction factor of semi-elliptical surface cracks present in a finite thickness plate and a thick walled cylinder corresponding to a wide range of configurations. The numerical results reported in the study are in close agreement with that of previous literature. A finite thickness plate with two coplanar self-same shallow and deep semi-elliptical surface cracks subjected to remote tensile surface traction is considered for fracture analysis. Based on extended finite element solutions MATLAB code has been generated for determining stress intensity factors along the entire crack front. A wide range of geometric dimensions and crack configurations viz. crack shape aspect ratio (0:3 ≤ a/c≤ 1:2), crack depth ratio (1:25 ≤ t/a ≤ 6), relative crack location (0:33≤ 2c/d≤ 0:9) and normalized location on the crack front (0 ≤ 2φ/π≤ 2) are considered for numerical estimation of crack interaction factors. SIFs evaluated at the depth point using the XFEM method and compared with SIFs evaluated using 3D finite element results using force method. Also extended finite element method has been used to analyze the interaction of two coplanar identical semi-elliptical surface cracks in the internal surface of a thick walled cylinder. The mode I stress intensity factor along the crack front were determined. In total 36 crack configurations were analyzed. It has been observed that interaction factor (γ) are greatest at φ=50 as the a/d ratio increases. For the same t/Ri, as a/d increases the interaction factor are greater for b/t=0.2 as compared to b/t =0.8.

Volume 11 | 05-Special Issue

Pages: 2265-2280