Publication: Análisis y modelización de vigas de tipo laminado sometidas a cargas impulsivas
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2007
Defense date
2007-07-04
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Abstract
En esta tesis se ha estudiado el comportamiento dinámico a flexión de vigas
constituidas por materiales compuestos de tipo laminado. Estos materiales son
cada vez más utilizados en todo tipo de industrias, destacando en las industrias
aeronáutica y aeroespacial por sus excelentes propiedades mecánicas específicas.
Se ha desarrollado un modelo analítico simplificado que considera tensiones de
cortadura interlaminar y la existencia de acoplamiento entre esfuerzos de flexión y
torsión, empleando el método de las funciones de influencia para su resolución
que tiene la ventaja de ser un método independiente de las condiciones de
contorno. El modelo ha sido validado mediante la comparación con un modelo
numérico implementado en un código de elementos finitos y con ensayos
experimentales.
Se ha implementado un modelo de comportamiento mecánico para laminados que
considera diferentes mecanismos de fallo en un código de elementos finitos
mediante una subrutina de usuario, que ha sido validado para la simulación de
estructuras tipo viga sometidas a cargas impulsivas. Así mismo, este modelo ha
sido empleado para analizar la influencia de la energía de impacto y de la
geometría de la probeta en los resultados del ensayo de flexión dinámica.
Se ha realizado un estudio de tolerancia al daño a flexión sobre vigas de tipo
laminado generando el daño mediante dos tipos de impacto que generan
esfuerzos de flexión. Se ha estimado el daño producido mediante inspección por
ultrasonidos y se han evaluado las propiedades residuales a flexión por ser el
estado de carga más común en este tipo de estructuras. Se ha analizado la
influencia del tipo de impacto y de la energía de impacto en las propiedades
residuales a flexión.
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In this PhD thesis the behaviour of laminate beams has been studied under dynamics bending loads. Composite materials are frequently used in aeronautic and aerospace industries because of their excellent specific mechanical properties. A simplified analytical model was developed considering interlaminar shear stresses and bending-torsion coupled effect. To solve model equations the influence functions method was applied because this method is independent of the boundary conditions. The influence functions method was validated comparing the results with those obtained by finite element method and experimental tests. A mechanical behaviour model for laminates considering multiple failure models and erosion criterion was implemented in a commercial finite element code. This model was validated for simulating composite failure under impulsive bending loads by comparing with experimental results. The model was applied to study the influence of impact energy in the dynamic bending test results. A study of bending damage tolerance of composite beams after two kinds of low velocity impact was carried out. The damage was evaluated by ultrasonic inspection and the residual mechanical properties were estimated by three points bending test because beams usually work under bending loads. The kind of impact and the impact energy were analyzed as the most important factors in the bending residual properties.
In this PhD thesis the behaviour of laminate beams has been studied under dynamics bending loads. Composite materials are frequently used in aeronautic and aerospace industries because of their excellent specific mechanical properties. A simplified analytical model was developed considering interlaminar shear stresses and bending-torsion coupled effect. To solve model equations the influence functions method was applied because this method is independent of the boundary conditions. The influence functions method was validated comparing the results with those obtained by finite element method and experimental tests. A mechanical behaviour model for laminates considering multiple failure models and erosion criterion was implemented in a commercial finite element code. This model was validated for simulating composite failure under impulsive bending loads by comparing with experimental results. The model was applied to study the influence of impact energy in the dynamic bending test results. A study of bending damage tolerance of composite beams after two kinds of low velocity impact was carried out. The damage was evaluated by ultrasonic inspection and the residual mechanical properties were estimated by three points bending test because beams usually work under bending loads. The kind of impact and the impact energy were analyzed as the most important factors in the bending residual properties.
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Keywords
Mecánica de sólidos, Resistencia de materiales, Ensayo de materiales, Materiales compuestos, Propiedades mecánicas