Publication: Ecuaciones constitutivas de materiales termoviscoplásticos. Aplicación a un polímero de uso estructural
Loading...
Identifiers
Publication date
2014-06
Defense date
2014-07-18
Authors
Advisors
Tutors
Journal Title
Journal ISSN
Volume Title
Publisher
Impact
Export
Abstract
Gran parte de los materiales presentan un comportamiento termoviscoplástico, existiendo numerosas aplicaciones en las que el estudio del efecto de la temperatura y de la velocidad de deformación es indispensable, justificando la necesidad de avanzar en su conocimiento y modelización. En esta Tesis Doctoral se presenta un modelo de plastificación para el estudio del comportamiento termoviscoplástico de polímeros, partiendo de otros recogidos en la literatura y considerando ecuaciones constitutivas adicionales. Se ha desarrollado un algoritmo consistente para integrar implícitamente las ecuaciones constitutivas del modelo, que recoge las características fundamentales del comportamiento de estos materiales, como es la influencia de la velocidad de deformación, de la temperatura y del estado tensional a través de tres invariantes del tensor de tensiones, así como las posibles diferencias de comportamiento entre tracción y compresión presentes en los polímeros. El algoritmo se ha implementado mediante una subrutina de usuario de un código comercial de Elementos Finitos. La verificación del modelo propuesto se ha realizado empleando un polímero de referencia (PMMA). Para ello, ha sido necesario realizar una campaña experimental que incluye ensayos de caracterización del material y diferentes ensayos que permiten estudiar la influencia de los distintos factores en su comportamiento. Concretamente, se han llevado a cabo ensayos de calibración de ciertos parámetros del modelo y, finalmente, ensayos de validación que permiten contrastar las predicciones numéricas con su correspondiente resultado experimental.
Most materials presents thermo-viscoplastic behavior, existing several applications where the effects of temperature and strain rate are essential, so it is necessary to improve its knowledge and modelling. In this Ph.D. Thesis, it is developed a plasticity model to study the thermo-viscoplastic behavior of polymers, considering previous models included in the bibliography. A consistent algorithm has been proposed to integrate implicitly the constitutive equations of the model, taking into account the effects of strain rate, temperature and stress state, considering three invariants of the stress tensor. Moreover, it incorporates the differences between the tensile and compressive behaviors. The algorithm has been implemented as a user’s subroutine in a Finite Element commercial code. The model has been verified using a specific polymer (PMMA). To do this, experimental tests have been carried out, including the characterization of the material, to study the influence of the parameters of the model. In particular, some parameters have been calibrated and, finally, the model has been validated comparing numerical with experimental results.
Most materials presents thermo-viscoplastic behavior, existing several applications where the effects of temperature and strain rate are essential, so it is necessary to improve its knowledge and modelling. In this Ph.D. Thesis, it is developed a plasticity model to study the thermo-viscoplastic behavior of polymers, considering previous models included in the bibliography. A consistent algorithm has been proposed to integrate implicitly the constitutive equations of the model, taking into account the effects of strain rate, temperature and stress state, considering three invariants of the stress tensor. Moreover, it incorporates the differences between the tensile and compressive behaviors. The algorithm has been implemented as a user’s subroutine in a Finite Element commercial code. The model has been verified using a specific polymer (PMMA). To do this, experimental tests have been carried out, including the characterization of the material, to study the influence of the parameters of the model. In particular, some parameters have been calibrated and, finally, the model has been validated comparing numerical with experimental results.
Description
Keywords
Ensayo de materiales, Polímeros, Comportamiento termoviscoplástico, Ecuaciones constitutivas avanzadas