13th International Conference on Fracture June 16–21, 2013, Beijing, China -1- Crack Growth-based Fatigue Life Prediction Using Spline Fictitious Boundary Element Method Cheng Su1,2,*, Chun Zheng1 1 School of Civil Engineering and Transportation, South China University of Technology, Guangzhou 510640, PR China 2 State Key Laboratory of Subtropical Building Science, South China University of Technology, Guangzhou 510640, PR China * Corresponding author: cvchsu@scut.edu.cn (C. Su) Abstract Fatigue life prediction is of great importance to the design and maintenance of structural components. A boundary element method (BEM)-based approach is proposed in this paper for fatigue life prediction using crack growth analysis. The proposed methodology is based on the well-known Paris equation for fatigue crack growth rate, which is related to the amplitude of the stress intensity factor (SIF) as a crack grows. The SIF is determined by the fracture spline fictitious boundary element method (SFBEM) based on the Erdogan fundamental solutions for plane cracked problems. The fusion of SFBEM and the Erdogan fundamental solutions is computationally efficient and provides a powerful tool for crack growth-based fatigue life prediction. A numerical example based on the mode-I crack problem is presented to validate the present method. The results show that the predicted fatigue life obtained by the present approach is accurate in comparison with the analytic solution. Keywords Fatigue crack growth, life prediction, fracture mechanics, spline fictitious boundary element method 1. Introduction According to a survey conducted by the ASCE Committee on Fatigue and Fracture Reliability [1], fatigue is the main reason that causes the failure in steel structures. Therefore, fatigue life prediction is an important task for the design and maintenance planning of structures. In general, there are two major types of approaches to predict the fatigue life [2]. The first is based on S-N curves combined with a damage accumulation rule. The second is based on the fracture mechanics and crack growth analysis. Generally, these two approaches are used sequentially. The one with S-N curves is used at the ‘design’ stage, and the one with fracture mechanics is used at the ‘assessment’ stage for existing structures [3]. From the point of view that initial flaws inevitably exist in engineering materials, the crack growth analysis based on fracture mechanics may be more suitable for refined fatigue life prediction of structural components. Crack growth theories have formed the bridge that links fatigue and fracture mechanics concepts [4]. The most important contribution is the establishment of the relationships between the crack growth rate da/dN and the stress intensity factor (SIF). The most widely used fatigue crack growth model, commonly known as Paris law, was proposed by Paris and Erdogan [5]. The Paris law connects the crack growth rate with the amplitude of SIF through a simple power function, which makes the engineering application more easily. After that, various modifications and extensions to Paris law have emerged, and different forms of modified crack growth equations have been offered by Forman [6], Elber [7] and Walker [8], et al. Another important task in the crack growth-based fatigue life prediction is the fracture analysis. Since few analytical solutions to SIFs are available, especially for engineering structures, numerical
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