International Journal of Composite Materials 2015, 5(2): 25-29 DOI: 10.5923/j.cmaterials.20150502.01 Effect of Hygrothermal Aging and Circular Notch on Tensile Strenght of Woven Composite Materials Repaired by a Bonded Composite Patch Djilali Beida Maamar 1 , R. Zenasni 1,* , Jaime Vina Olay 2 , Antonio Arguelles Amado 3 1 University of Mostaganem, Department of Mechanics, Mostaganem, Algeria 2 University of Oviedo, Department of Material Sciences, Gijon, Spain 3 University of Oviedo, Department of Construction, Gijon, Spain Abstract The process of repair of structures by using the bonding of composites is an effective and economic method to increase the durability of the damaged components. This article addresses the experimental characterization of the effect of bonded composite patch on the tensile strength behavior of two woven glass fiber and carbon composite materials. After cutting the tensile specimens with a numerical controlled machine, two series of samples were mechanized with different types of notches. Of each composite material, two series of specimens were drilled with a different central hole of diameter 2, 4,6 mm. The second series were exposed to hygrothermal aging during 180 days. The hygrothermal conditions were of temperature 70°C and relative humidity of 95%. Of each composite material, one group was repaired with a composite patch which the material was the same of the specimen material. The tensile test was performed to all the specimens. The displacement and the maximum load were tailored. The tensile load of glass fiber composite decrease quickly than carbon fiber. The double patch had more efficiency than a single patch. The SEM reveals a fracture of fiber bundles and a rich-resin zones. Keywords 8H satin woven fabric, Glass fiber, Carbon fiber, Bonded Patch repair, Tensile strength, Circular notch, SEM 1. Introduction Recently, the use of the adhesives is accepted in a process of repair of the structures in order to increase the lifespan of the damaged components. The metal or composite parts are bonded to one side or the two sides of the cracked part in order to extend its lifespan of service [1-6]. The repair of the cracks by bonding of composite material patch has proved its efficiency to reduce the stress intensity in a crack tips, in other words to reduce the propagation velocity of the cracks. This method is employed to repair the damaged plane components. Considerable research was carried out to develop the technology of bonding the patches in composites in the aeronautical structures. Alan Baker had conducted many research [7-9] based on simple analyses, or experimental testing. The development of the super computers had conducted the use of the finite element method to model the effectiveness of repair. The bonded patches offer several advantages among which, the improvement of the fatigue life of the material, the reduction * Corresponding author: zramdane@netcourrier.com (R. Zenasni) Published online at http://journal.sapub.org/cmaterials Copyright © 2015 Scientific & Academic Publishing. All Rights Reserved of corrosion and the easy suitable to the complex aerodynamic shape. The finite element method gives with a higher degree of accuracy the stress intensity factor at the crack tip. The authors have used the method of calculation of the factor in the case of stiffened cracks, Bachir B. et al. [10]. Heung Soo K. et al [11] investigated the three dimensional stress analysis of a composite patch using stress functions. The analysis shown, that the interlaminar stresses reach the maximum at the free edge and decrease at the inner part of the patch. The proposed method accurately predicts the tridimensional stresses in a composite patch bonded on the metal, it can be used for designing structural components. Adhesively bonded joints have found important application areas in the marine and offshore industry during the last years. One particular application is the use of bonded patches to repair steel structures such as floating production storage and offloading units. Harald O. et al [12] used the finite element analysis for the adhesive bondline. It is a powerful tool in strength predictions of adhesively bonded joints. S.P et al [13], have studied the micromechanical behavior by finite element of the 2/2 twill weave T300 carbon/epoxy woven fabric composite laminates. Circular holes of different sizes were drilled in a composite. Based on the uniaxial, shear and Von Mises stress distributions in the yarn and matrix, the influence of hole-size on the stress