Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleYalnız künye2026Scopus SJRQ2Influence of infill design on mechanical behavior of PLA-TPU hybrid sandwich beams
Arikan, Volkan; Dogan, Akar; Guler, Serkan
The purpose of this work is to analyze the mechanical behavior of hybrid sandwich beams that were printed using the Fused Deposition Modelling (FDM) technology. These beams were made of Polylactic Acid (PLA) and Thermoplastic Polyurethane (TPU) materials. Standard mechanical tests (ASTM C393 and C365) were utilized in order to assess the impact that several infill patterns (Cubic, Octet, and Trihexagonal) and infill densities (ranging from 15% to 40%) had on the flexural and compression performance of the material. According to the findings, trihexagonal patterns demonstrated improved energy absorption capabilities when subjected to compression, but octet designs offered superior flexural stiffness, particularly in hybrid constructions. According to the findings of tests conducted with hybrid constructions consisting of a TPU core and a PLA surface layer, the effect of infill patterns on component strength is directly influenced by the change in the material character, and it is possible that various materials would exhibit different manifestations of this effect. These findings offer useful information that may be used to optimize lattice geometry and hybridization procedures for the purpose of developing high-performance lightweight structures for engineering applications.
AtıfWoS1OpenAlex2
İncele - MakaleYalnız künye2025Scopus SJRQ2Investigation of Mechanical Properties of Jute and Tea Waste-Reinforced Epoxy Composite Material Produced by Vacuum Assisted Resin Infusion Molding
Dogan, Akar; Mahmat, Aybars; Agar, Salih
Recently, the production of materials obtained from plant sources has been increasing due to their environmentally friendly and sustainable sources. Natural fibers and waste materials offer a remarkable alternative in composite production due to their biodegradability, low cost and renewability. In this study, composite materials were produced using hybrid Jute and industrial tea waste-reinforced epoxy materials by vacuum assisted resin infusion molding. In this context, the reason for using natural and industrial resources such as jute fiber and tea waste is to contribute to both the improvement of mechanical properties and the reduction of environmental impacts. It was observed that tensile and flexural strength decreased as the amount of tea waste increased. Conversely, the energy absorbed during the quasi-static punch shear and Charpy impact tests increased, unlike the tensile and flexural strength. Approximately 50% decrease was observed in the tensile strength of the 60% tea waste reinforced material compared to the pure jute composite material. In Charpy impact and quasi-static punch shear tests, a 5% increase in the energy absorbed in the 60% tea waste reinforced composite materials was obtained.
AtıfScopus2WoS1OpenAlex1İncele - MakaleYalnız künye2025Scopus SJRQ1Multivariable assessment of ınfill strategies for enhanced mechanical properties in 3D-printed curved beams
Arıkan, Volkan; Dogan, Akar
Purpose – This study specifically focuses on low-to-medium infill densities where the influence of internal geometry on structural performance becomes most dominant. This study aims to explore how different infill patterns and densities affect the mechanical response of curved-axis beams produced by fused filament fabrication-based additive manufacturing (AM), providing insights for optimizing lightweight and material-efficient components subjected to bending loads. Design/methodology/approach – Twenty-seven PLA-based specimens with varying curvature radii (500, 750 and 1000 mm), infill patterns (grid, triangular and trihexagonal) and densities (20%, 30% and 40%) were manufactured. Each was subjected to three-point bending tests following ASTM standards. The experimental approach focused on analyzing force-displacement behavior to evaluate stiffness, load capacity and deformation characteristics under static loading conditions. Findings – Increasing infill density enhanced the maximum force capacity of curved beams but reduced their displacement tolerance, reflecting greater rigidity. The trihexagonal (TH) pattern exhibited the highest displacement values, confirming its energy absorption capability, while the triangular (TA) pattern provided the greatest rigidity with lower deformation. The grid (GR) pattern showed intermediate behavior, with displacement capacity strongly influenced by curvature radius. Straighter beams generally displayed reduced displacement and higher stability, while more curved beams exhibited greater deformation. These results highlight the critical role of infill geometry and curvature in balancing strength, stiffness and energy absorption in three-dimensional (3D)-printed curved beams. Originality/value – Unlike prior studies that focus on high or near-solid infill levels, this work uniquely highlights the mechanical response of additively manufactured curved beams within the low-to-medium infill density range, where infill geometry plays a critical role. The study presents the first detailed comparison of how infill strategies interact with curvature in 3D-printed beams. It delivers practical design guidance for engineers working with curved structures in mechanical, aerospace and civil applications. Its novelty lies in demonstrating how trihexagonal patterns can optimize performance across various geometries, supporting enhanced structural resilience in AM.
- MakaleYalnız künye2023Scopus SJRQ2Effect of impactor nose form on the impact behavior of reinforced composite materials
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.
AtıfScopus7WoS7OpenAlex6İncele - MakaleYalnız künye2022Scopus SJRQ2Single and repeated low-velocity impact response of E-glass fiber-reinforced epoxy and polypropylene composites for different impactor shapes
Dogan, Akar
This study focuses on the effects of low-velocity impact (LVI) response of thermoset (TS) and thermoplastic (TP) matrix-based composites. In this study, the effects of the impactor shapes on the low-velocity impact response of the composite panels that produced from different matrix was investigated. Unidirectional E-glass fiber fabrics with an areal density of 300 g/m2 as reinforcement and epoxy matrix were used to produce TS composite. The vacuum-assisted resin infusion molding (VARIM) method was used to manufacture composite panels. The thermoplastic composites were manufactured with E-glass fiber-reinforced polypropylene prepregs. The tensile strength of TS matrix-based composites is higher than TP matrix-based composites that have the same fiber volume fraction. Despite being under the same impact energy, the TP specimens possess higher perforation threshold than TS specimens. The shape of the impactor significantly affected the perforation threshold. Besides, the impact number that caused perforation reduced dramatically in conical impactor. The repeated impact number that caused perforation is 36 for hemispherical (HS) impactor, but it is only 3 for conical impactor for polypropylene matrix-based composite. Moreover, a significant effect of fiber volumetric ratio on impact resistance was observed. The perforation threshold of glass fiber-reinforced polypropylene composites for 40% and 50% fiber volume fraction are 61 and 98 J, respectively. The perforation threshold of TP and TS specimens for HS impactor that has the same stacking sequence is 61 and 55 J, respectively.
AtıfScopus42WoS45OpenAlex44İncele - MakaleYalnız künye2022Scopus SJRQ2Characterization of the mechanical and thermal properties of rape short natural-fiber reinforced thermoplastic composites
Kısmet, Yılmaz; Dogan, Akar
In this study, the effects of filler amounts were studied on the mechanical and thermal properties of high-density polyethylene (HDPE), polystyrene (PS) and polyoxymethylene (POM) polymers reinforced with short rape fibers. HDPE-rape, POM-rape and PS-rape fiber composite materials were prepared with different fiber contents and their tensile, flexural, Izod impact and TGA/DTA properties were examined. When tensile and Izod impact properties were compared, it was observed that an increase in the amount of filling in HDPE-based composites did not cause any significant changes in these peoperties, while they were decreased for POM- and PS-based composites. On the contrary to tensile and impact strengths, when the three-point flexural properties were examined, it was observed that the strength values of all these materials increased with increasing the amount of fillers. However, a pronounced increase was observed in the three-point flexural strength of the HDPE-based composite materials. The flexural strength of 30 wt% rape-reinforced HDPE composite was found to be twice that of the pure HDPE. The results of TGA and DTA analyses revealed that the reinforcement element started to burn before the matrix material and therefore burning was delayed in these thermoplastics. As a result, the mechanical properties of HDPE composite materials improved with rape reinforcement. In this way, by using approximately 30 wt% natural filling material in a polymeric matrix, an environmentally friendly material, as well as, significant advantages in cost can be obtained. Graphic abstract: [Figure not available: see fulltext.].
AtıfScopus25WoS25OpenAlex33İncele - MakaleYalnız künye2021Scopus SJRQ2High temperature effect on quasi-static and low velocity impact behaviors of advanced composite materials
Karakuzu, Ramazan; Djele, Akim; Dogan, Akar
In this study, the effect of ambient temperatures on the punch shear and low-velocity impact behavior of S2 glass fabric and carbon-kevlar hybrid fabric reinforced epoxy composites was investigated. The quasi-static tests (QST) were performed by using a Universal Shimadzu Tensile Testing Machine with various crosshead speeds. Low-velocity impact (LVI) tests were also carried out by using the CEAST Fractovis Plus impact test machine at different impact energies. Flat-nose impactors with a cylindrical punch diameter of 12.70 mm were mounted to the test machines. Both tests have been carried out at various temperatures. After the experiments, the load-displacement, the absorbed energy-impact energy/crosshead speed and punch shear strength graphs are plotted. From the obtained results it can be said that, in penetration cases of low-velocity impact and quasi-static tests, absorbed energy and punch shear strength values show similar behavior for hybrid carbon-kevlar/epoxy at each temperature except for 80 °C while these values are different from each other for S2 glass/epoxy at all temperatures.
AtıfScopus16WoS14OpenAlex14İncele - MakaleAçık Erişim2021Scopus SJRQ1Thermoset powder coating wastes as filler in LDPE – Characterization of mechanical, thermal and morphological properties
Kismet, Yilmaz; Dogan, Akar; Wagner, Manfred H.
In this study, three different electrostatic powder coating wastes of thermoset structure were used as fillers for low-density polyethylene (LDPE). The mechanical, thermal, and morphological properties of these composites materials are reported. The thermoset powder coating wastes were hydrolyzed using water and alcohol, and then 10%, 20%, and 30% by weight of the deactivated wastes were mixed with LDPE, first in a mechanical dry mixer, and subsequently homogenized by melt compounding in an extruder at about 160 °C. Standard tensile test bars and plate-shaped samples were produced from these homogeneous compounds by injection molding. The effects of adding hydrolyzed powder coating wastes on the properties of LDPE were determined by mechanical, thermal, and morphological tests. Tensile strength and perforation threshold of the sample filled with powder coating wastes decreased to some extent compared to un-filled sample. However, an increase in izod impact and bending strengths has been observed. The results of this investigation demonstrate that powder coating wastes with thermoset structure can be used as fillers in LDPE.
AtıfScopus13WoS15OpenAlex16İncele - MakaleYalnız künye2021Scopus SJRQ1Low-velocity impact, bending, and compression response of carbon fiber/epoxy-based sandwich composites with different types of core materials
Dogan, Akar
This study focuses on the investigation of the effects of different core types on the low velocity impact, three-point bending and out-of-plane compression loading performance of sandwich composites. Three core materials were selected: Balsa wood, PVC foam, and Ayous wood. The facesheets of sandwich composites were produced by woven carbon/epoxy. Balsa and PVC foam are widely used in sandwich composites as core materials. In this study, Ayous wood, which is the lightest tree after Balsa, was used as core material in addition to traditional core materials. Woven carbon fiber fabrics with an areal density 200 g/m2 as reinforcement and epoxy matrix were used to produce the sandwich composite. Vacuum-assisted resin infusion molding method was used to manufacture composite panels. A number of tests under various impact energy levels for three different sandwich composites were conducted with Fractovis Plus impact testing machine in order to investigate the energy absorption capacity of sandwich composites. Maximum contact forces, absorbed energies, and the maximum deflections of sandwich panels were obtained for each impact energy level. Despite having the same facesheets, Ayous core sandwich composites possess a higher perforation threshold than Balsa and PVC foam sandwich composites. The perforation threshold of Balsa, PVC foam, and Ayous sandwich composites are 85, 72, and 170 J, respectively. In addition, the Ayous core sandwich composites have better bending and compression strengths. The bending strength of the Ayous sandwich composite is higher about six times than PVC sandwich composite and about two times than Balsa sandwich composite.
AtıfScopus61WoS56OpenAlex56İncele - MakaleYalnız künye2019Scopus SJRQ2Experimental investigation of transverse loading on composite panels coated with different gelcoat colors subjected to UV radiation and hygrothermal aging
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.
AtıfScopus12WoS9OpenAlex11İncele - MakaleYalnız künye2019Scopus SJRQ2The effect of hygrothermal aging and UV radiation on the low-velocity impact behavior of the glass fiber-reinforced epoxy composites
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.
AtıfScopus48WoS43OpenAlex48İncele - MakaleYalnız künye2019Scopus SJRQ3Effects of temperature and impactor nose diameter on the impact behavior of PA6 and PP thermoplastic composites
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.
AtıfScopus7WoS6OpenAlex6İncele - MakaleAçık Erişim2018Scopus SJRQ4The effect of hygrothermal aging on the glass and carbon reinforced epoxy composites for different stacking sequences
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.
AtıfScopus22WoS19OpenAlex23İncele - MakaleYalnız künye2015Scopus SJRQ2Effects of Temperature and Hole Drilling on Adhesively Bonded Single-Lap Joints
Arikan, Volkan; Dogan, Akar; Dogan, Tolga; Sabanci, Eray; Al-Shamary, Adel Kadum Jassim
In this study, the load-carrying capacity of a single-lap joint bonded by an adhesive was determined experimentally. Glass fiber-epoxy composite material was chosen as adherends and Loctite (R) 9466 A&B2 was used as adhesive. The vacuum assisted resin infusion method (VARIM) was used to manufacture composites. In this experimental study, the effects of hole drilling and temperature were investigated. Five hole configurations and three temperatures (room temperature, 50 degrees C, and 80 degrees C) were considered. The results show that hole drilling elevate the failure load and when the temperature increases the load-carrying capacity decreases.
AtıfWoS20OpenAlex21İncele