Estudio del desempeño mecánico y balístico de bajo calibre de un compuesto reforzado con fibra natural.
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Date
2024
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Universidad de Concepción
Abstract
Esta investigación se centra en el desarrollo, caracterización y evaluación del desempeño mecánico y balístico de bajo calibre de materiales compuestos híbridos a base de Kevlar y fibra natural de cáñamo, utilizando una matriz de resina epóxica. La motivación de este trabajo, se debe principalmente a la creciente demanda de materiales sostenibles y eficientes en la industria, especialmente en aplicaciones de protección balística de bajo calibre, como chalecos antibalas. La investigación aborda la necesidad de materiales que no solo ofrezcan alta resistencia y durabilidad, sino que también sean amigables con el medio ambiente. El Kevlar es una fibra sintética conocida por su alta resistencia a la tracción, ligereza y capacidad para absorber impactos, lo que la convierte en un componente crucial. Sin embargo, el costo elevado y el impacto ambiental de su producción han llevado a explorar alternativas más sostenibles. En este contexto, el cáñamo emerge como una fibra natural prometedora debido a sus propiedades mecánicas, bajo costo, biodegradabilidad y menor impacto ambiental.
La metodología empleada abarcó, en primera instancia, la selección y preparación de materiales basándose en la literatura existente, seguida de la distribución estratégica de las capas del material compuesto. Para ello, se diseñó y fabricó un molde de acero que permitió la producción de placas compuestas de Kevlar/resina y cáñamo/resina mediante el proceso de laminado manual. Las placas fabricadas fueron evaluadas mediante ensayos mecánicos de tracción y corte, siguiendo las normativas ASTM D3039 y D4255, para determinar propiedades claves como la resistencia a la tracción, el módulo elástico y el comportamiento al corte. Los resultados experimentales mostraron que los compuestos de Kevlar tienen propiedades mecánicas superiores a las de los compuestos de cáñamo.
Los datos obtenidos en los ensayos fueron utilizados como parámetros de entrada en el software especializado en impactos Ansys LS-DYNA, con el propósito de realizar simulaciones que replicaran las condiciones de impactos balísticos de bajo calibre siguiendo los estándares de la norma NIJ II. Estas simulaciones permitieron evaluar las capacidades individuales de los materiales, así como sus combinaciones en configuraciones híbridas, analizando si los compuestos podrían alcanzar una energía de absorción comparable a la del Kevlar puro. Las configuraciones utilizadas en las simulaciones fueron: Solo Kevlar; Híbrido B (cáñamo/Kevlar/Kevlar/cáñamo); Híbrido C (Kevlar/cáñamo/cáñamo/Kevlar); Híbrido D (cáñamo/Kevlar/cáñamo/Kevlar) y Solo cáñamo.
Los resultados obtenidos de la simulaciones revelaron que la absorción de energía tras el impacto balístico fue de 36.84 J, 29.97 J, 20.76 J, 16.46 J y 3.23 J para las configuraciones de Solo Kevlar, Híbrido B, Híbrido C, Híbrido D y Solo cáñamo, respectivamente. El Híbrido B presento la energía absorbida más cercana al compuesto de Solo Kevlar, aunque con un espesor de 11 mm, en comparación con los 7 mm del Kevlar puro. Esto posiciona al Híbrido B como la configuración híbrida con el mejor desempeño, aunque su eficacia sigue siendo limitada debido a que se obtuvieron peores resultados que el compuesto con Kevlar puro. En contraste, el compuesto de Solo Cáñamo mostro una capacidad de absorción de energía prácticamente nula, a pesar de tener el mismo espesor que el Kevlar, evidenciando su limitada efectividad como material balístico. Adicionalmente, se observó que bajo las condiciones de impacto simuladas, ninguna de las configuraciones evaluadas logró evitar la penetración completa del proyectil.
This research focuses on the development, characterization, and evaluation of the mechanical and low-caliber ballistic performance of hybrid composite materials based on Kevlar and natural hemp fiber, using an epoxy resin matrix. The motivation for this work stems from the growing demand for sustainable and efficient materials in the industry, particularly for low-caliber ballistic protection applications, such as bulletproof vests. The study addresses the need for materials that not only provide high strength and durability but are also environmentally friendly. Kevlar, a synthetic fiber, is known for its high tensile strength, lightness, and impact absorption capabilities, making it a critical component. However, its high cost and environmental impact have driven the search for more sustainable alternatives. In this context, hemp emerges as a promising natural fiber due to its mechanical properties, low cost, biodegradability, and reduced environmental footprint. The methodology included material selection and preparation based on existing literature, followed by the strategic layering of the composite material. A steel mold was designed and manufactured to produce Kevlar/resin and hemp/resin composite plates using a hand lay-up process. The fabricated plates were evaluated through mechanical testing, including tensile and shear tests, in compliance with ASTM D3039 and D4255 standards, to determine key properties such as tensile strength, elastic modulus, and shear behavior. Experimental results showed that Kevlar composites possess superior mechanical properties compared to hemp composites. The data obtained from the tests were used as input parameters in the specialized impact simulation software Ansys LS-DYNA to replicate low-caliber ballistic impact conditions following NIJ II standards. These simulations evaluated the individual capabilities of the materials as well as their hybrid configurations to determine whether the composites could achieve energy absorption levels comparable to pure Kevlar. The simulated configurations included: Pure Kevlar; Hybrid B (hemp/Kevlar/Kevlar/hemp); Hybrid C (Kevlar/hemp/hemp/Kevlar); Hybrid D (hemp/Kevlar/hemp/Kevlar); and Pure Hemp. Simulation results revealed energy absorption values of 36.84 J, 29.97 J, 20.76 J, 16.46 J, and 3.23 J for the configurations of Pure Kevlar, Hybrid B, Hybrid C, Hybrid D, and Pure Hemp, respectively. Hybrid B demonstrated the closest energy absorption to Pure Kevlar, albeit with a thickness of 11 mm compared to 7 mm for pure Kevlar. This positions Hybrid B as the hybrid configuration with the best performance, although its efficiency remains limited as it achieved lower results than the pure Kevlar composite. In contrast, the Pure Hemp composite exhibited virtually no energy absorption capability despite having the same thickness as Kevlar, highlighting its limited effectiveness as a ballistic material. Additionally, under the simulated impact conditions, none of the evaluated configurations prevented complete projectile penetration.
This research focuses on the development, characterization, and evaluation of the mechanical and low-caliber ballistic performance of hybrid composite materials based on Kevlar and natural hemp fiber, using an epoxy resin matrix. The motivation for this work stems from the growing demand for sustainable and efficient materials in the industry, particularly for low-caliber ballistic protection applications, such as bulletproof vests. The study addresses the need for materials that not only provide high strength and durability but are also environmentally friendly. Kevlar, a synthetic fiber, is known for its high tensile strength, lightness, and impact absorption capabilities, making it a critical component. However, its high cost and environmental impact have driven the search for more sustainable alternatives. In this context, hemp emerges as a promising natural fiber due to its mechanical properties, low cost, biodegradability, and reduced environmental footprint. The methodology included material selection and preparation based on existing literature, followed by the strategic layering of the composite material. A steel mold was designed and manufactured to produce Kevlar/resin and hemp/resin composite plates using a hand lay-up process. The fabricated plates were evaluated through mechanical testing, including tensile and shear tests, in compliance with ASTM D3039 and D4255 standards, to determine key properties such as tensile strength, elastic modulus, and shear behavior. Experimental results showed that Kevlar composites possess superior mechanical properties compared to hemp composites. The data obtained from the tests were used as input parameters in the specialized impact simulation software Ansys LS-DYNA to replicate low-caliber ballistic impact conditions following NIJ II standards. These simulations evaluated the individual capabilities of the materials as well as their hybrid configurations to determine whether the composites could achieve energy absorption levels comparable to pure Kevlar. The simulated configurations included: Pure Kevlar; Hybrid B (hemp/Kevlar/Kevlar/hemp); Hybrid C (Kevlar/hemp/hemp/Kevlar); Hybrid D (hemp/Kevlar/hemp/Kevlar); and Pure Hemp. Simulation results revealed energy absorption values of 36.84 J, 29.97 J, 20.76 J, 16.46 J, and 3.23 J for the configurations of Pure Kevlar, Hybrid B, Hybrid C, Hybrid D, and Pure Hemp, respectively. Hybrid B demonstrated the closest energy absorption to Pure Kevlar, albeit with a thickness of 11 mm compared to 7 mm for pure Kevlar. This positions Hybrid B as the hybrid configuration with the best performance, although its efficiency remains limited as it achieved lower results than the pure Kevlar composite. In contrast, the Pure Hemp composite exhibited virtually no energy absorption capability despite having the same thickness as Kevlar, highlighting its limited effectiveness as a ballistic material. Additionally, under the simulated impact conditions, none of the evaluated configurations prevented complete projectile penetration.
Description
Tesis presentada para optar al título profesional de Ingeniero Civil Mecánico
Keywords
Materiales, Fibras vegetales, Fibras poliamidas