Abstract
In this study, multiple and non-planar crack propagation analyses are performed using Fracture and Crack Propagation Analysis System (FCPAS). In an effort to apply and validate FCPAS procedures for multiple and non-planar crack propagation analyses, various problems are solved and the results are compared with data available in the literature. The method makes use of finite elements, specifically three-dimensional enriched elements to compute stress intensity factors (SIFs) without special meshing requirements. A fatigue crack propagation criterion, such as Paris-Erdo?an equation, is also used along with stress intensity factors to conduct the simulation. Finite element models are generated within ANSYS™ software, converted into and solved in FRAC3D program, which employs enriched crack tip elements. Having computed the SIFs for a given crack growth increment and using a growth criterion, the next incremental crack path is predicted and the fracture model is updated to reflect the non-planar crack growth. This procedure is repeated until cracks reach a desired length or when SIFs exceed the fracture toughness of the material. It is shown that FCPAS results are in good agreement with literature data in terms of SIFs, crack paths and crack growth life of the structure. Thus, accuracy and reliability of FCPAS software for multiple and non-planar crack propagation in thin structures is proven.
Highlights
In-plane crack propagation under mode-I loading conditions is very common for machinery parts and structures and is still a popular research subject, some parts can fail under mixed mode loading, causing nonplanar crack surface
Leonel et al used two-dimensional boundary element method (BEM) method for multiple crack propagation analyses [4]. They used maximum circumferential stress theory for evaluating stress intensity factors (SIF) and propagation angle, and Paris’ law to predict structural life. Another 2D linear elastic fracture mechanics (LEFM) problem is analyzed by Yan [5] using BEM method for propagating multiple cracks
It should be noted that during the analyses presented in this paper, the maximum crack length increment among all propagation steps is taken to be nearly one-tenth of the largest crack length and that these steps can further be refined to further check the convergence of the crack path and life predictions
Summary
In-plane crack propagation under mode-I loading conditions is very common for machinery parts and structures and is still a popular research subject, some parts can fail under mixed mode loading, causing nonplanar crack surface. There are several numerical and experimental studies that deal with fracture and propagation analyses of multiple cracks and nonplanar crack growth. Jonesa et al [2] analyzed interacting multiple cracks using finite element method (FEM) and a hybrid formulation which represents stiffness changes. Leonel et al used two-dimensional BEM method for multiple crack propagation analyses [4] They used maximum circumferential stress theory for evaluating stress intensity factors (SIF) and propagation angle, and Paris’ law to predict structural life. Another 2D linear elastic fracture mechanics (LEFM) problem is analyzed by Yan [5] using BEM method for propagating multiple cracks. It is shown that FCPAS results for multiple non-planar cracks agree well with those from the literature
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