Analysis of crack growth problems using the object-oriented program bemcracker2D

Abstract

This paper presents an application of the boundary element method to the analysis of crack growth problems in linear elastic fracture mechanics and the correlation of results with experimental data. The methodology consists of computing stress intensity factors (SIFs), the crack growth path and the estimation of fatigue life, via an incremental analysis of the crack extension, considering two independent boundary integral equations, the displacement and traction integral equations. Moreover, a special purpose educational program for simulating two-dimensional crack growth based on the dual boundary element method (DBEM), named BemCracker2D, written in C++ with a MATLAB graphic user interface, has been developed and used to verify the adopted methodology. The numerical results are compared with those of the finite element method (FEM) and correlated with experimental data of fatigue crack-growth tests for twodimensional structural components under simple loading, aiming to demonstrate the accuracy and efficiency of the methodology adopted, as well as to evaluate the robustness of the BemCracker2D code.

Adaptive Finite Element Prediction of Fatigue Life and Crack Path in 2D Structural Components

“…Figure 5 shows the initial adaptive finite element mesh for this geometry, as seen in the enlargement of the rosette elements around the crack tip which was refined with a uniform element size in order to capture the severity of the plastic deformation near the crack tip. For CT01, CT02, CT03, and CT04 in Figures 6-9, respectively, comparisons are made between the results of the present study and the experimental and numerical fatigue crack growth paths conducted by [40,41]. As seen, the predicted crack growth directions in the present study were almost similar to the paths that were predicted experimentally and numerically using the boundary element method (BEM) with BemCracker 2D and finite element method with Quebra2, D (FEM) [40,41].…”

“…For CT01, CT02, CT03, and CT04 in Figures 6-9, respectively, comparisons are made between the results of the present study and the experimental and numerical fatigue crack growth paths conducted by [40,41]. As seen, the predicted crack growth directions in the present study were almost similar to the paths that were predicted experimentally and numerically using the boundary element method (BEM) with BemCracker 2D and finite element method with Quebra2, D (FEM) [40,41]. Additionally, the maximum principal stresses for the four different MCTS configurations are shown in Figure 10.…”

“…Numerous handbooks can also provide analytical calculations of the SIF for the standard CT geometry. The SIF solution is formulated as follows for the standard CT specimen [40][41][42].…”

“…The f(a/w) patterns vary from each other, as shown, as the curved crack path is formed. Furthermore, the results of this analysis for the dimensionless SIF f(a/w) were compared with the dimensionless stress factor values calculated by [41] using BEM with BemCracker2D software and the FEM with Quebra2D (FEM) for the four different configurations as seen in Figures 10-14. It can be seen from these figures that the results of this analysis are closely associated with Quera2D rather than BemCracker2D.…”

Numerical Analysis of Fatigue Crack Growth Path and Life Predictions for Linear Elastic Material

“…As soon as the crack is growing, the SIF will shift to a critical range in which the structure deformation initiates leading to the failure process. The majority of fatigue-crack problems reported in the literature till date are using various methods of analysis in terms of two- and three-dimensional simulation for simple as well as complex geometries [ 8 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ], etc.. Because of the complexity of applied loads and the geometry specification, mixed mode (I/II) are the usual types of loads that depend on those used in fatigue life predictions [ 19 , 20 , 21 , 22 ]. Hence, this work utilizes the XEFM employed by ANSYS APDL 19.2 to determine the influence of the hole position in the crack growth direction, stress intensity factors and also fatigue life of the modified compact tension specimen (MCTS) specimen.…”