Determination of weight function to analyze the coefficient of stress intensity and fatigue life of thick-walled tanks based on the function of displacement of cracks

Determining the stress intensity coefficient is the main parameter in reservoir design, and what in the linear failure mechanism controls the crack behavior is the value of the stress intensity coefficient. There are different ways to estimate this value. The weight function method is widely used as one of the stress intensity estimation methods. In this paper, the weight function based on estimating the crack displacement function is obtained using modeling in software in a specific geometry of the ball tube. Then, using the weight function, the stress intensity coefficient and the fatigue life of the ball tube in the case of autophagy, using the actual behavior of the material, are obtained and compared with the available results. The method presented in this paper is a general method that can be applied to any geometry of the tank with any number of internal or external cracks and any relative length of cracks.