Abstract
The fatigue life curves of materials are very sensitive to the magnitude of the stress amplitude. A small change or inaccuracy in the determination of the stress value causes large changes or inaccuracies in the calculated fatigue life estimate. Therefore, the use of computer simulations for fatigue life estimation requires a proper model development methodology. The paper is devoted to the problem of the modeling of components in notches using FEM. The modeling parameters significantly influencing the obtained stress results have been defined. Exact analytical solutions served as a benchmark for comparing the accuracy of the stress values obtained using FEM models. For the selected 2D and 3D notched components, diagrams were created for sensitivity analysis of the influence of the mesh element density at the root of the notch in correlation with the exact analytical solution. The findings from model building were applied to model the stress concentration at the root of a V-weld joint in a gas pipeline.
Highlights
For a reliable assessment of the fatigue life of a structure, it is necessary to define two types of input parameters: load parameters and material parameters
To verify the simulation results, as a first step, the following cases of notch effects, for which analytical solutions are known, were chosen: Two-dimensional problems: a circular hole in the center of a wide sheet in tension, opposite a circular groove in a thin plate loaded in tension and a stepped thin sheet loaded in tension
The stress value at the critical location of the structure, where the stress concentration is usually present, is one of the key input values determining the accuracy of the computational estimation of its fatigue life
Summary
For a reliable assessment of the fatigue life of a structure, it is necessary to define two types of input parameters: load parameters and material parameters. The accuracy and validity with which these parameters are obtained directly affect the results of the fatigue life assessment. For both groups of parameters, it is best to obtain them by direct measurement. An acceptable approach for obtaining an accurate and valid stress history at a critical location in a structure may be a combination of direct measurement and computer simulation: direct measurement at the nominal stress (strain) location and accurate simulation of the notching effect at the critical location. The model creation procedure offers a number of parameters that have a significant impact on the result obtained These parameters and their effects will be identified, analyzed and quantified later in the paper in order to objectify the use of computational simulations for fatigue life estimation purposes
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