Modelo microstructural iterativo para la predicción de fallo a fatiga de componentes finitos
- Autores: Nicolás Óscar Larrosa
- Directores de la Tesis: A. Navarro Robles (dir. tes.)
- Lectura: En la Universidad de Sevilla ( España ) en 2012
- Idioma: español
- Tribunal Calificador de la Tesis: Jaime Domínguez Abascal (presid.), Eugenio Giner Maravilla (secret.), M. Neil James (voc.), John Yates (voc.), Luca Susmel (voc.)
- Materias:
- Enlaces
- Tesis en acceso abierto en: TESEO
- Resumen
This thesis consists of the development of an alternating method that includes a micromechanical model that enables the calculation of the fatigue limit of sophisticated arbitrary shaped and sized geometries subjected to complex boundary conditions.
The model, based on previous models for fatigue analysis in infinite or semi-infinite media, includes new features such as the introduction of the boundary effect, the analyses of complex geometries, the possibility of including different kinds of loading condition and the effect of fretting and residual stresses.
In the introduction (Chapter 1), a framework to the development of the Thesis is given.
Chapter 2 is dedicated to describe short fatigue cracks. The importance of the study and the state of the art is described. Several assessment models for the calculation of the fatigue limit are presented. Then, the micromechanical model implemented to describe the Mode I short crack growth is introduced. The formulation of the model is presented and the details that concerns how the cracks, plastic zones and barriers are modeled by the method are described. The advantages and disadvantages of the method for the assessment of fatigue parameters of mechanical components are discussed.
In Chapter 4, the ideas behind the Schwarz-Neumann alternating method are presented. Next, the finite element alternating method (FEAM) formulation is developed. The FEAM is implemented and verified by the calculation of SIF¿s of various published benchmark problems.
Chapter 5 treats the inclusion of the micromechanical model into the FEAM scheme, resulting in what the author calls the Microstructural FEAM or MFEAM, the numerical tool developed to model the fatigue behavior of finite components. The iterative scheme of the numerical tool is described. The MFEAM is tested solving several problems of known solution. The calculation of the fatigue limit for different notched components is compared to the results obtained by other authors experimentally and with other calculation methods. Semicircular notches, circular notches, U-notches, V-notches and arbitrary shape components are evaluated. Some of these examples could not have been solved with the tools available at the moment. A convergence analysis is performed in order to show the robustness and reliability of the method.
Chapter 6 shows the capability of the method to include typical fatigue features: residual stresses and fretting. This chapter presents an example in which is shown that inclusion of residual stresses is straightforward within the MFEAM formulation. Comparison with experimental data is performed. Finally, the effect of fretting fatigue is tackled. Prediction for the fatigue response of four different fretting fatigue conditions are analyzed and compared with classical models and experimental results.
Finally, in Chapter 7, a finite thickness solution is included in the MFEAM formulation, in what the authors called the 2.5D-MFEAM. An introductory first approach is presented. With this formulation, more realistic problems can be solved leaving behind the necessity of choosing plain stress or plain strain approximations. An example of an embedded crack is presented in order show the potential benefit of using this formulation. The thickness effect is studied in this example and the fatigue response of an infinite plate of finite thickness is assessed.
