Publication: Comportamiento de estructuras de material compuestos sometidas a cargas impulsivas
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2012-02
Defense date
2012-04-18
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Abstract
En esta tesis se ha estudiado el comportamiento frente a impacto, tanto de alta velocidad como de baja velocidad, de diversas estructuras fabricadas con distintos materiales compuestos. Se han analizado estructuras sándwich de fibra de vidrio con núcleo de espuma de polivinilo y de pieles de fibra de carbono con núcleo de panal de abeja de aluminio, así como laminados monolíticos de fibra de vidrio/poliéster y carbono/epoxi. Se evalúo la respuesta frente a impacto de baja velocidad de estructuras sándwich, evaluando la influencia de la energía de impacto en la fuerza máxima y la energía absorbida, así como un estudio del daño generado por el impacto de dichas probetas, el cual fue realizado haciendo uso de técnicas de ensayo no destructivo mediante inspección visual y ultrasonido. Se ha desarrollado un modelo analítico basado en criterios energéticos aplicable a laminados delgados carbono/epoxi sujetos a impactos de alta velocidad de proyectiles de poca masa. Este modelo ha sido validado mediante ensayos experimentales y mediante un modelo numérico; con este modelo ha sido posible determinar la velocidad residual del proyectil y deducir el límite balístico. El modelo también permite estimar la contribución de diferentes mecanismos a la absorción de la energía cinética del proyectil. Con este modelo se ha evaluado la influencia del espesor y de la velocidad de impacto en ambos parámetros. Se aplicó un modelo numérico detallado para las estructuras sándwich estudiadas implementado en Abaqus/Explicit, validándolo con los resultados experimentales. Con este modelo se evaluó la influencia del núcleo en el comportamiento frente a impacto, comparando con una estructura sin núcleo denominada placas espaciadas, también se evaluó la influencia del ratio espesor pieles/espesor núcleo. Este estudio se complementó con resultados experimentales en los que se evaluó el daño generado. ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
In this PhD thesis the impact behavior of both high velocity and low velocity of various structures made from different composite materials has been studied. Sandwich structures have been analyzed fiberglass with polyvinyl foam core and carbon fiber skins with honeycomb core of aluminum, and monolithic laminated fiberglass/polyester and carbon/epoxy. The evaluation of response to low-velocity was conducted with the study of the influence of impact energy in the maximum force and absorbed energy, and damage area generated by the impact of these specimens, which was conducted by use of nondestructive testing techniques by visual inspection and ultrasound. A simplified analytical model was developed based on energy criteria applicable to thin laminated carbon/epoxy subjected to high velocity impacts of low-mass projectiles. This model has been validated by experimental tests and by a numerical model, this model has been possible to determine the residual velocity and ballistic limit deduced. The model also allows us to estimate the contribution of different mechanisms of absorption of the kinetic energy of the projectile. This model evaluated the influence of the thickness and velocity of impact on both parameters. We performed a detailed numerical model for the studied sandwich structures implemented in Abaqus/Explicit, validating it with experimental results. This model evaluated the influence of the nucleus in the impact behavior, compared to a structure coreless called spaced plate, we also have evaluated the influence of skin thickness/core thickness ratio. This study is complemented by experimental results that evaluated the damage generated.
In this PhD thesis the impact behavior of both high velocity and low velocity of various structures made from different composite materials has been studied. Sandwich structures have been analyzed fiberglass with polyvinyl foam core and carbon fiber skins with honeycomb core of aluminum, and monolithic laminated fiberglass/polyester and carbon/epoxy. The evaluation of response to low-velocity was conducted with the study of the influence of impact energy in the maximum force and absorbed energy, and damage area generated by the impact of these specimens, which was conducted by use of nondestructive testing techniques by visual inspection and ultrasound. A simplified analytical model was developed based on energy criteria applicable to thin laminated carbon/epoxy subjected to high velocity impacts of low-mass projectiles. This model has been validated by experimental tests and by a numerical model, this model has been possible to determine the residual velocity and ballistic limit deduced. The model also allows us to estimate the contribution of different mechanisms of absorption of the kinetic energy of the projectile. This model evaluated the influence of the thickness and velocity of impact on both parameters. We performed a detailed numerical model for the studied sandwich structures implemented in Abaqus/Explicit, validating it with experimental results. This model evaluated the influence of the nucleus in the impact behavior, compared to a structure coreless called spaced plate, we also have evaluated the influence of skin thickness/core thickness ratio. This study is complemented by experimental results that evaluated the damage generated.
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Materiales compuestos, Estructuras sándwich, Comportamiento frente a impacto