Publication: Análisis experimental y numérico del comportamiento mecánico del material compuesto base aramida empleado en protecciones personales
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2021-06
Defense date
2021-07-23
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Abstract
Los esfuerzos por mejorar las protecciones personales se han incrementado en
los últimos años debido al reciente aumento reciente aumento del terrorismo civil
y conflictos internacionales, permitiendo minimizar la morbilidad y mortalidad
resultante de traumatismos cráneo-encefálicos por amenaza balística. En la actualidad
se destinan continuos esfuerzos para reducir aún más el peso del casco
sin disminución de la resistencia balística, la cual está regulada por estrictas normativas.
Esta es actualmente una de las principales preocupaciones de las fuerzas
armadas y de industria de seguridad. El uso de materiales compuestos, concretamente
el material compuesto base aramida, ha cobrado mayor relevancia en los
últimos años en el sector de la defensa y la industria de la seguridad, debido a su
alta resistencia al impacto y notable capacidad de absorción de energía combinado
con un bajo peso.
Alineado con lo mencionado anteriormente, el objetivo de esta tesis doctoral
es el desarrollo de una herramienta numérica predictiva, capaz de reproducir el
comportamiento frente a impacto balístico del material compuesto de fibra de
aramida, empleado en el desarrollo y fabricación de protecciones personales. El
interés de los fabricantes de disminuir el coste de desarrollo de una protección
personal justifica el objetivo planteado. Para la consecución de dicho objetivo se
ha desarrollado una metodología combinada experimental y numérica que permite
calibrar los modelos de elementos _nitos de simulación en placa plana y su
correspondiente validación en modelos numéricos impacto en casco de combate, a
través de ensayos experimentales sobre protecciones reales. Una de las principales
características del modelo numérico desarrollado, es la modelización multicapa
del material compuesto que permite discretizar el laminado en sub-laminas independientes,
permitiendo de este modo, escoger el número de capas necesario para
alcanzar un nivel de protección determinado y otorgando al modelo un nivel alto de realismo y precisión.
De manera complementaria, se ha llevado a cabo una campaña completa de
ensayos experimentales sobre placa plana sometida a impacto de baja velocidad
con el _n de analizar el comportamiento del material ante este tipo de cargas
dinámicas. Los resultados obtenidos han proporcionado parámetros relevantes
para el desarrollo de los modelos numéricos de impacto balístico.
La calibración y validación se ha realizado a través de diferentes análisis empleando
proyectiles de diferentes geometrías, masas y velocidades de impacto.
En primer lugar, se analizan diferentes parámetros como el límite balístico y las
curvas balísticas, así como la influencia de la densidad areal de la protección.
Seguidamente, se ha llevado a cabo un análisis cualitativo y cuantitativo de del
daño inducido a consecuencia del impacto y la relación de este con la absorción
de energía. Una buena correlación entre los resultados experimentales y los proporcionados
por el modelo numérico valida el modelo numérico propuesto.
El modelo presentado resulta una herramienta de gran potencial para el diseño
y fabricación de cascos de combate debido a la versatilidad de aplicación que
posee, permitiendo ajustar el número de capas exacto atendiendo al nivel de
protección a alcanzar.
Efforts to improve personal protection have increased in recent years due to the recent increase in civilian terrorism and international conicts, making it possible to minimize morbidity and mortality resulting from head and brain trauma due to ballistic threat. Continuous efforts are now being made to further reduce helmet weight without reducing ballistic resistance, which is regulated by strict standards. Currently, this is one of the main concerns of the armed forces and the security industry. The use of composite materials, specifically aramid-based composite material, has gained more prominence in recent years in the defense and security industry, due to its high impact resistance and remarkable energy absorption capacity combined with low weight. Aligned with the aforementioned, the main goal of this thesis is the development of a predictive numerical tool, capable of reproducing the behavior against ballistic impact of the aramid fiber composite material, used in the development and manufacture of personal protection. The interest of manufacturers in reducing the cost of developing personal protection justifies the stated objective. To achieve this objective, a combined experimental and numerical methodology has been developed that allows calibrating the at plate simulation finite element models and their corresponding validation in numerical models of impact in combat helmet, through experimental tests on real protections. One of the main characteristics of the numerical model developed is the multilayer modeling of the composite material that allows the laminate to be discretized into independent sub-layers, thus allowing the choice of the number of layers necessary to achieve a certain level of protection and giving the model a high level of realism and precision. Complementary to this, a complete experimental series tests on a at plate subjected to low-velocity impact has been carried out in order to analyze the behavior of the material under this type of dynamic loads. The results obtained have provided relevant parameters for the development of numerical models of ballistic impact. The calibration and validation has been carried out through different analyzes using projectiles of different geometries, masses and impact velocities. First, different parameters such as the ballistic limit and ballistic curves are analyzed, as well as the inuence of the areal density of the protection. Subsequently, a qualitative and quantitative analysis of the damage induced as a result of the impact and its relationship with energy absorption was carried out. A good correlation between the experimental results and those provided by the numerical model validates the proposed numerical model. The model presented is a high potential tool for combat helmet design and manufacturing due to the versatility of its application, allowing the exact number of layers to be adjusted according to the level of protection to be achieved.
Efforts to improve personal protection have increased in recent years due to the recent increase in civilian terrorism and international conicts, making it possible to minimize morbidity and mortality resulting from head and brain trauma due to ballistic threat. Continuous efforts are now being made to further reduce helmet weight without reducing ballistic resistance, which is regulated by strict standards. Currently, this is one of the main concerns of the armed forces and the security industry. The use of composite materials, specifically aramid-based composite material, has gained more prominence in recent years in the defense and security industry, due to its high impact resistance and remarkable energy absorption capacity combined with low weight. Aligned with the aforementioned, the main goal of this thesis is the development of a predictive numerical tool, capable of reproducing the behavior against ballistic impact of the aramid fiber composite material, used in the development and manufacture of personal protection. The interest of manufacturers in reducing the cost of developing personal protection justifies the stated objective. To achieve this objective, a combined experimental and numerical methodology has been developed that allows calibrating the at plate simulation finite element models and their corresponding validation in numerical models of impact in combat helmet, through experimental tests on real protections. One of the main characteristics of the numerical model developed is the multilayer modeling of the composite material that allows the laminate to be discretized into independent sub-layers, thus allowing the choice of the number of layers necessary to achieve a certain level of protection and giving the model a high level of realism and precision. Complementary to this, a complete experimental series tests on a at plate subjected to low-velocity impact has been carried out in order to analyze the behavior of the material under this type of dynamic loads. The results obtained have provided relevant parameters for the development of numerical models of ballistic impact. The calibration and validation has been carried out through different analyzes using projectiles of different geometries, masses and impact velocities. First, different parameters such as the ballistic limit and ballistic curves are analyzed, as well as the inuence of the areal density of the protection. Subsequently, a qualitative and quantitative analysis of the damage induced as a result of the impact and its relationship with energy absorption was carried out. A good correlation between the experimental results and those provided by the numerical model validates the proposed numerical model. The model presented is a high potential tool for combat helmet design and manufacturing due to the versatility of its application, allowing the exact number of layers to be adjusted according to the level of protection to be achieved.
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Keywords
Protecciones personales, Materiales compuestos, Ensayo de materiales, Impacto balístico, Aramida, Método de Elementos Finitos, Modelo numérico