Abstract
Composite materials have been increasingly used in both researches and industries, given their wide range of innovative applications and configurations. High-performance hybrid fabric-reinforced plastics stand out in this sector. In the present research, an epoxy-based vinyl ester resin laminate reinforced with bidirectional hybrid fabric consisting of carbon and Kevlar fibers is developed. In order to determine its mechanical properties and damage mechanism considering the anisotropy and the presence of geometric discontinuity (circular hole), this research focused on both experimental and analytical aspect. Concerning to geometric discontinuity, in the vicinity of the hole (known as a stress concentration area), characteristic distances ao and do associated to ASC (Average Stress Criterion) and PSC (Point Stress Criterion) failure theories, respectively, were determined. All the study of the composite material mechanical behavior was conducted based on uniaxial tensile tests. Their results show higher losses in the mechanical properties of the hybrid laminate, with respect to the anisotropy and the presence of the central hole, mainly when the orientation of the Kevlar fibers coincides with the direction of the applied load.
Highlights
Technological advances and commercial demands have prompted an increase in the development of new materials in recent decades
Polymer composite materials, known as fiber-reinforced plastics (FRP)[1,2], have a special highlight. Included in this category of composite materials there are the plastics reinforced with hybrid fabrics of high mechanical performance, ie, reinforcing fabrics made of synthetic fiber[3,4,5,6]
Values recorded for bulk density and resin, fiber and void percentage are in accordance with other types of reinforcement and the manufacturing process used[24]
Summary
Technological advances and commercial demands have prompted an increase in the development of new materials in recent decades. The initial analytical study is based on the calculation of the residual properties, using the concepts established by ASTM standard D 5766-1118; such as residual strength (RS) and residual modulus (RM), both obtained experimentally These residual properties, and the PSC (Point Stress Criterion) and ASC (Average Stress Criterion) failure theories contained in the literature[19] were used in semi-empirical determination of the characteristic distances (do and ao) of the stress concentration area surrounding the hole. As a final step of the experiment, a global comparative study between the influences of anisotropy and geometric discontinuity on CL behavior was carried out, considering these parameters separately and simultaneously, in order to better understand the results and its influence During this stage, the damage mechanism process of the laminate was studied and mechanical fracture was analyzed using scanning electron microscopy (SEM)
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