Publication: Modelos de fractura dúctil en condiciones estáticas y dinámicas
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2007
Defense date
2007-07-05
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Abstract
En esta tesis se han abordado algunos problemas de simulación numérica del comportamiento de materiales cuyos micromecanismos de fractura están regidos por la nucleación, crecimiento y coalescencia de microvacíos. Este tipo de fenómenos aparecen en muchas aplicaciones de ingeniería como son los procesos de fabricación por conformado y corte, el análisis del comportamiento frente a choque de estructuras de vehículos
ligeros (automóviles, helicópteros), la predicción de la propagación de fisuras en paneles
de pequeñoo espesor, típicos en la industria aeronáutica, el diseño de protecciones contra
impacto balístico, entre otros.
En particular, se ha propuesto un algoritmo consistente para integrar las ecuaciones
constitutivas de materiales de Gurson aplicable a problemas termoviscoplásticos, teniendo
en cuenta la influencia de la velocidad de deformación y la temperatura en el comportamiento.
También se ha formulado una variante del modelo de Gurson considerando que algunos parámetros del mismo no son constantes, sino dependientes de la triaxialidad del
campo tensional. Se ha desarrollado el correspondiente algoritmo de integración de las
ecuaciones de este modelo modificado y, en este caso, se ha aplicado a problemas estáticos.
Finalmente, se ha aplicado el modelo de Gurson para analizar la influencia de la
porosidad inicial en las inestabilidades por cavitación en metales dúctiles.
Los algoritmos desarrollados se han implementado en códigos comerciales de elementos finitos, se ha comprobado su funcionamiento y se han validado con resultados experimentales
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In this thesis, some problems about numerical simulation of the mechanical behaviour of materials whose fracture mechanisms are related to the nucleation, growth and coalescence of voids have been analized. This kind of analysis must be performed in many engineering applications like metal forming and cutting, light vehicles structures (automobiles, helicopters) under crashing, crack growth in thin panels, typical in the aircraft industry, high-speed impact on metallic armours and others. In particular, a consistent integration algorithm of Gurson's constitutive equations considering strain rate and thermal effects has been developed. Also, a modified GTN model that considers that some parameters of the model are no constant but dependent of stress state has been formulated. Finally, the influence of the porosity on cavitation instabilities in metallic materials has been analyzed. In previous work, this kind of instabilities has been predicted considering only one void contained in an unbounded solid. The developed algorithms have been implemented in a Finite Element commercial code and they have been validated with experimental results
In this thesis, some problems about numerical simulation of the mechanical behaviour of materials whose fracture mechanisms are related to the nucleation, growth and coalescence of voids have been analized. This kind of analysis must be performed in many engineering applications like metal forming and cutting, light vehicles structures (automobiles, helicopters) under crashing, crack growth in thin panels, typical in the aircraft industry, high-speed impact on metallic armours and others. In particular, a consistent integration algorithm of Gurson's constitutive equations considering strain rate and thermal effects has been developed. Also, a modified GTN model that considers that some parameters of the model are no constant but dependent of stress state has been formulated. Finally, the influence of the porosity on cavitation instabilities in metallic materials has been analyzed. In previous work, this kind of instabilities has been predicted considering only one void contained in an unbounded solid. The developed algorithms have been implemented in a Finite Element commercial code and they have been validated with experimental results
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Keywords
Ensayo de materiales, Resistencia de materiales, Simulación numérica, Fractura