Simulación del ensayo 45° Fiber Bundle Test.
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Date
2025
Journal Title
Journal ISSN
Volume Title
Publisher
Universidad de Concepción
Abstract
En este trabajo se desarrolla un modelo de simulación multiescala de una vía para el análisis mecánico de materiales compuestos utilizando el ensayo 45FBT, con énfasis en la caracterización de la interfase entre la fibra y la matriz. El objetivo principal es estimar la resistencia al corte interfacial (IFSS) a partir de una simulación por elementos finitos que integre tanto el comportamiento macroscópico del material como la respuesta microscópica de sus constituyentes. Para ello, se identifican las propiedades relevantes de la fibra y la matriz, y se implementa un modelo de acoplamiento global-local unidireccional, donde las deformaciones obtenidas a nivel macroscópico se aplican a un volumen representativo (RVE) a nivel microscópico, construido en APDL. El RVE incluye la interfase como una tercera fase, lo que permite evaluar su influencia en la distribución de esfuerzos. Los resultados obtenidos muestran que la distribución de esfuerzos de corte simulada concuerda en forma con los datos experimentales, aunque presenta diferencias de magnitud atribuibles a las idealizaciones geométricas del modelo, como el arreglo hexagonal de fibras en vez de un arreglo aleatorio. Se identificaron las zonas de mayor concentración de esfuerzos en la interfase, coherentes con los modos de falla observados en la literatura. Además, se estimó el IFSS mediante dos enfoques: el valor máximo y el promedio sobre la interfase, obteniendo 35.42 MPa y 25.23 MPa, respectivamente, ambos dentro de los rangos reportados para compuestos con matriz epoxi y refuerzo de fibra de carbono. Este trabajo demuestra que es posible estimar el IFSS de manera efectiva sin recurrir a sistemas ópticos avanzados, utilizando únicamente propiedades de los constituyentes y parámetros de ensayo al momento del fallo. Finalmente, se identifican posibles líneas de desarrollo futuro, como el uso de modelos cohesivos, acoplamiento bidireccional, y métodos micromecánicas más avanzados como el GMC, con el objetivo de mejorar la precisión del análisis y extender su aplicabilidad.
In this work, a one-way multiscale model is developed for the mechanical analysis of composite materials using the 45FBT test, with emphasis on the interphase characterization that is between the fiber and the matrix. The main goal is to measure the interfacial shear strength (IFSS) from a finite element simulation that takes into account both the macroscopic response and the microscopic one between the constituents of the composite. To achieve this, the relevant properties of the fiber and matrix are identified and implemented in a one-way global coupling model, where the strains are obtained at the macroscopic level and then applied to the Representative Volume Element (RVE) at the microscopic level, built in APDL. The RVE takes into account the interphase as a third phase, enabling evaluation of its influence on the stress distribution. The results obtained show that the simulated shear stress distribution somewhat matches the experimental data, although a difference in magnitude is seen and attributed to the geometric idealization of the model, such as the hexagonal arrangement of fibers instead of a random one. The highest stress concentration in the interphase is identified, consistent with the failure mode reported in the literature. Furthermore, IFSS was estimated in two ways: the maximum value and the average of the elements, obtaining 35.42 MPa and 25.23 MPa respectively, both within the reported range for composites with an epoxy matrix and carbon fiber reinforcement. This work shows that it is possible to estimate the IFSS effectively without the need for advanced optical systems, using only the constituents’ properties and the test parameters. Finally, possible lines of future work are identified, like the use of cohesive zone models, bidirectional coupling, and more advanced micromechanical methods like GMC, with the objective of improving the accuracy of the analysis and broadening its applicability.
In this work, a one-way multiscale model is developed for the mechanical analysis of composite materials using the 45FBT test, with emphasis on the interphase characterization that is between the fiber and the matrix. The main goal is to measure the interfacial shear strength (IFSS) from a finite element simulation that takes into account both the macroscopic response and the microscopic one between the constituents of the composite. To achieve this, the relevant properties of the fiber and matrix are identified and implemented in a one-way global coupling model, where the strains are obtained at the macroscopic level and then applied to the Representative Volume Element (RVE) at the microscopic level, built in APDL. The RVE takes into account the interphase as a third phase, enabling evaluation of its influence on the stress distribution. The results obtained show that the simulated shear stress distribution somewhat matches the experimental data, although a difference in magnitude is seen and attributed to the geometric idealization of the model, such as the hexagonal arrangement of fibers instead of a random one. The highest stress concentration in the interphase is identified, consistent with the failure mode reported in the literature. Furthermore, IFSS was estimated in two ways: the maximum value and the average of the elements, obtaining 35.42 MPa and 25.23 MPa respectively, both within the reported range for composites with an epoxy matrix and carbon fiber reinforcement. This work shows that it is possible to estimate the IFSS effectively without the need for advanced optical systems, using only the constituents’ properties and the test parameters. Finally, possible lines of future work are identified, like the use of cohesive zone models, bidirectional coupling, and more advanced micromechanical methods like GMC, with the objective of improving the accuracy of the analysis and broadening its applicability.
Description
Tesis presentada para optar al título de Ingeniero/a Civil Mecánico/a.
Keywords
Materiales Análisis, Resistencia de materiales, Micromecánica