Fracture Mechanisms in Fiber Reinforced Polymer Matrix Composites
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Fracture Mechanisms in Fiber Reinforced Polymer Matrix Composites C. Rodríguez1,2,3, M. Hinojosa1,2, J. Aldaco1,2 and A. Cázares1,2,3 1 Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, México. 2 Centro de Innovación, Investigación y Desarrollo en Ingeniería y Tecnología, Universidad Autónoma de Nuevo León, México. 3 Centro de Investigación e Innovación en Ingeniería Aeronáutica, Universidad Autónoma de Nuevo León, México. ABSTRACT In this work we report the fractographic study of polymer matrix composites specimens reinforced with glass and carbon fibers. Specimens of a polyester matrix composite with 30% of E-glass fibers are prepared and fractured in flexure mode. We also test an epoxy matrix composite with 30% carbon fibers, which is fractured in flexure mode. All specimens are manufactured based on the D790 ASTM standard for bending mode at room temperature. As an exception, the composites with epoxy matrix and reinforced with carbon fiber are cured in an autoclave. The most commonly observed fracture mechanisms are debonding in the interphase, delamination, Chevron lines, microbuckling, river patterns and radial fracture on the fibers. INTRODUCTION Over time scientists have developed models and theories to investigate fracture, crack propagation and nucleation. The origins of fracture mechanics can be traced back to an article published by Griffith (1920), demonstrating that actual tension resistance in brittle materials is significantly lower than the theoretically predicted strength due to the presence of cracks [1]. Over years models and theories has been develop for the study the nucleation and propagation of cracks. One of the most important is Fiber Bundle Model (FBM) introduced by Peires in 1927 to understand the load applied in cotton. The FBM construction assumes the next conditions: discretization, shear load law, failure distribution and time dependence. For composite materials some investigations has been develop as R.C Hidalgo [2], analyzing the heterogeneities of the materials in response to the fracture. Nowadays engineers use Finite Element (FE) models to predict properties and failure modes in materials. A virtual test describes the capability of providing a blind prediction by simulating the behavior of the physical structure. Such a prediction is expected to provide the resistance value of the structure in order to ensure proper sizing conditions. This also assumes the ability to describe the effects on local depths, progressive damage to localized material failure, and all consequential effects until the collapse of the final structure [3]. Fiber reinforced composite materials are replacing standard isotropic materials in many applications. Aerospace vehicles, aircraft, marine equipment, and common items such as civil structures, prosthetic devices, and sports equipment are currently being constructed of such composite materials. The primary advantage of composite materials is their inherent ability to be custom tailored to a specific design situation. Constit
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