Dogan, Sonay; Arman, Yusuf; Dogan, Akar

The goal of the present study is to investigate the influence of impactor shape on the low-velocity impact behavior of the composite panels manufactured with different reinforcement materials at the same thicknesses, experimentally. Kevlar, carbon, S-2 glass woven fabric and epoxy matrix have been used to manufacture thermoset composites with the vacuum-assisted resin infusion molding method. The Fractovis plus test machine with a 12.7 mm diameter hemispherical and two different conical impactor noses was used to perform impact tests. The effects of impactor shapes on the low-velocity impact behavior have been compared for 20 J, 40 J, and 60 J energy levels. Although at the same impact energy level, S-2 glass fiber-reinforced epoxy specimens have a higher perforation threshold than carbon and Kevlar fiber-reinforced epoxy. Because to achieve the same thickness, the number of S-2 glass layers was greater than the number of carbon and Kevlar layers. Additionally, the form of the impactor greatly influenced the perforation threshold.

AtıfScopus7·WoS7·OpenAlex6

İncele

Dogan, Akar; Arman, Yusuf; Ozdemir, Okan

This study focuses on the effects of hygrothermal and UV radiation aging on the reinforced epoxy composites coated with gelcoat. The aim of this study is to investigate the influence of gelcoat colors on the tensile properties, impact behavior and thermodynamic properties of the composite panels after the aging process has been performed. Two different gelcoat colors were chosen as black and yellow. Unidirectional E-glass fiber fabrics with an areal density 300 g m-2 as reinforcement and epoxy matrix were used. Vacuum-assisted resin infusion molding (VARIM) method was used to manufacture composite panels. The tensile test specimens were prepared according to ASTM standards. Tensile strength of both fiber and transverse directions, the impact perforation threshold, and stroge modulus of the aged samples decreased compared to unaged (virgin) samples. However, the drop in mentioned properties for coated materials is less than for uncoated materials, especially in yellow coated materials. The temperature of hygrothermal conditions significantly affected the perforation threshold. Moreover, the tensile strength in transverse direction in yellow samples decreased approximately 13%, while it decreased 23% in the black coated samples. Impact perforation threshold of unaged (virgin), uncoated, coated with yellow gelcoat and coated with black gelcoat is obtained to be 75, 57, 65 and 61 J, respectively.

AtıfScopus12·WoS9·OpenAlex11

İncele

Dogan, Akar; Arman, Yusuf

The present work examines the effects of hygrothermal and UV radiation aging on the reinforced epoxy composites. The role of temperature in the hygrothermal aging process on tensile properties, impact behavior of composites and compression-after impact was investigated. Among four different chosen aging conditions, three of them were hygrothermal and last one was composed of both hygrothermal and UV radiation. Unidirectional e-glass fiber fabrics with an areal density 300 g/m2 as reinforcement and epoxy matrix were used. Composites were manufactured using vacuum-assisted resin infusion molding. The goal of this study was to investigate the effect of UV radiation and aging temperature with respect to the glass transition temperature. In this context, aging procedures were carried out in two different ways for 70 °C temperature with and without UV radiation. As a result of the test, the tensile strength, tensile modulus, absorbed energy, interlaminar shear strength (ILSS), and compression-after impact (CAI) strength of the glass reinforced composites decreased for all conditions. Despite being under the same ambient temperature and humidity, the samples which were exposed to UV radiation had lower mechanical properties. The reduction of tensile strength of specimens exposed to 70 °C and 70% humidity with and without UV radiation were 24% and 10%, respectively. The temperature of hygrothermal conditions significantly affected the perforation threshold. In low impact energies, delamination was the primary damage mode, while fiber breakage becomes more important in the composite at high impact energy levels.

AtıfScopus48·WoS43·OpenAlex48

İncele

Dogan, Akar; Arman, Yusuf

In this study, the effects of temperature and impactor nose diameter on the impact behavior of woven glass-reinforced polyamide 6 (PA6) and polypropylene (PP) thermoplastic composites were investigated experimentally. Impact energies are chosen as 10, 30, 50, 70, 90, 110, 130, and 170 J. The thickness of composite materials is 4 mm. Impact tests were performed using a drop weight impact testing machine, CEAST-Fractovis Plus, and the load capacity of test machine is 22 kN. Hemispherical impactor nose diameter of 12, 7, and 20 mm were used as an impactor. The tests are conducted at room temperature (20°C and 75°C). As a result, the PP composites of the same thickness absorbed more energy than PA6 composites. The amount of absorbed energy of PP and PA6 composites decreased with temperature.

AtıfScopus7·WoS6·OpenAlex6

İncele

Dogan, Akar; Arman, Yusuf

The present paper examines the effects of hygrothermal aging on the reinforced epoxy composites. The roles of reinforcement types and stacking sequence on the mechanical properties of composites under hygrothermal aging are investigated. Four different composite materials with different stacking sequence were produced. Unidirectional E-glass and carbon fabrics with an areal density 300 gr/m2 as reinforcement and epoxy as matrix were used. Composites were manufactured using vacuum-assisted resin infusion molding. In order to determine the mechanical properties of the composites, specimens were prepared according to the ASTM standards. The aging process was carried out in climatic test cabin at a temperature of 90oC and a humidity of 90%. As a result of the tests, while the tensile strength of the glass reinforced composites decreased with aging time, no significant change was observed for carbon and hybrid composites. On the other hand, the tensile strength decreased in the transverse direction for all types of composites. XPS analysis was used to understand the distribution of atoms on the surface of specimens.

AtıfScopus22·WoS19·OpenAlex23

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