Abstract
This study presents a developed finite element code written by Visual Fortran to computationally model fatigue crack growth (FCG) in arbitrary 2D structures with constant amplitude loading, using the linear elastic fracture mechanics (LEFM) concept. Accordingly, optimizing an FCG analysis, it is necessary to describe all the characteristics of the 2D model of the cracked component, including loads, support conditions, and material characteristics. The advancing front method has been used to generate the finite element mesh. The equivalent stress intensity factor was used as the onset criteria of crack propagation, since it is the main significant parameter that must be precisely predicted. As such, a criterion premised on direction (maximum circumferential stress theory) was implemented. After pre-processing, the analysis continues with incremental analysis of the crack growth, which is discretized into short straight segments. The adaptive mesh finite element method was used to perform the stress analysis for each increment. The displacement extrapolation technique was employed at each crack extension increment to compute the SIFs, which are then assessed by the maximum circumferential stress theory to determine the direction of the crack growth and predict the fatigue life as a function of crack length using a modified form of Paris’ law. The application examples demonstrate the developed program’s capability and performance.
Highlights
Fracture mechanics’ main goal is to figure out how quickly a crack’s shape changes.Will it grow and if it grows, at what rate and into what configuration under certain loadings and conditions? The computing requirements corresponded to obtaining the components stress, strain, energy, and displacement, which might extract the driving force for crack propagation
The potential of incorporating a portion of crack extensions in the service life of components provides the foundation for the development of the design principle known as “damage tolerant design,” which relates to components that are designed to operate with fatigue damage in a permissible limit [3]
A crack propagation developed program that hinged on the finite element method was used in probing problems involving holes with different initial crack locations
Summary
Fracture mechanics’ main goal is to figure out how quickly a crack’s shape changes. Will it grow and if it grows, at what rate and into what configuration under certain loadings and conditions? The computing requirements corresponded to obtaining the components stress, strain, energy, and displacement, which might extract the driving force for crack propagation. To evaluate the FCG in metallic and aircraft structures, conventional methods rely on LEFM to compute the fatigue life of these components under different loading and boundary conditions [2]. There are numerous stress intensity factors estimation handbooks for distinct geometries and loads [6,7,8,9] These numerical solutions cover a variety of geometries and loading conditions that are essential in predicting the structural failure of cracked bodies. The limitations of the analytical solution of SIFs suggest a numerical analysis approach to fracture problems in engineering practice, as it is almost impossible to prevent the occurrence of cracks in the structure, which may be caused by: production method, heat treatments of metals, transport, etc. The proposed program’s effectiveness was shown in a variety of scenarios with accurate results e.g., [18,25,26,27,28]
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