Development of Efficient Finite Element Software of Crack Propagation Simulation using Adaptive Mesh Strategy

Abstract

Abstract:The purpose of this study is on the determination of 2D crack paths and surfaces as well as on the evaluation of the stress intensity factors as a part of the damage tolerant assessment. Problem statement: The evaluation of SIFs and crack tip singular stresses for arbitrary fracture structure are a challenging problem, involving the calculation of the crack path and the crack propagation rates at each step especially under mixed mode loading. Approach: This study was provided a finite element code which produces results comparable to the current available commercial software. Throughout the simulation of crack propagation an automatic adaptive mesh was carried out in the vicinity of the crack front nodes and in the elements which represent the higher stresses distribution. The finite element mesh was generated using the advancing front method. The adaptive remising process carried out based on the posteriori stress error norm scheme to obtain an optimal mesh. The onset criterion of crack propagation was based on the stress intensity factors which provide as the most important parameter that must be accurately estimated. Facilitated by the singular elements, the displacement extrapolation technique is employed to calculate the stress intensity factor. Crack direction is predicted using the maximum circumferential stress theory. The fracture was modeled by the splitting node approach and the trajectory follows the successive linear extensions of each crack increment. The propagation process is driven by Linear Elastic Fracture Mechanics (LEFM) approach with minimum user interaction. Results: In evaluating the accuracy of the estimated stress intensity factors and the crack path predictions, the results were compared with sets of experimental data, benchmark analytical solutions as well as numerical results of other researchers. Conclusion/Recommendations: The assessment indicated that the program was highly reliable to evaluate the stress intensity factors and successfully predicts the cracks trajectories. Based on the results, it was recommended to add further development in the software to simulate crack propagation in elastoplastic materials.

FEM analysis of in-flight ice break-up

“…The plane strain condition is assumed in the analysis. Figure 29 shows the comparison of the final crack shape, along with the reference result of Alshoaibi and co-workers [42]. In Alshoaibi's paper, mesh adaptation based on adjoint error estimation around the crack tip is used, while in the present study, only mesh refinement with quarter-point element around the crack tip is adopted.…”

“…A well-known geometry used in the evaluation of crack propagation procedure is the single edge cracked plate [42]. Figure 28 shows the problem statement and final mesh of the test case.…”

“…Techniques for mesh refinement around the crack tip can be found in the literature [42,43], but in the present analysis, we adopt a simple approach where we identify a node very close to the crack tip and regenerate a new mesh. Since our mesh generation procedure ensures that the nodes specified in the input file remain unaltered, we automatically get a refined mesh around the crack tip.…”

Dynamic Behavior of Tyre Tread Block

“…The Finite element method is widely used in solving many engineering problems (Alshoaibi et al, 2009). The Contact between tyre and the road at static and dynamic situation was modeled and analyzed using ABAQUS Software.…”

Hybrid Algorithm for Optimal Load Sharing in Grid Computing

“…In EZ-GRID Broker (Ibrahim and Salman, 2011;Richard et al, 2008), job handling, transparent file transfer, self-information service ith dynamic and historical data, Policy Engine Framework for provider policies are proposed. In GRID BUS Grid Service system (Alshoaibi et al, 2009), Failure management and application recovery, parameter study, API support, Economybased and data aware scheduling are focused for solving. The GRUBER (Al-mazroi and Rashid, 2011) handles SLA-based resource sharing in multi-VO environment, disk quota considerations, internal site monitoring feature and various users oriented policies.…”