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Öğe A comprehensive experimental study on the effects of hexagonal boron nitride particle size and loading ratio on thermal and mechanical performance in epoxy composites(Sage Publications Ltd, 2024) Ozyigit, Samet; Mehdipour, Mostafa; Al-Nadhari, Abdulrahman; Tabrizi, Arvin T.; Dogan, Semih; Dericiler, Kuray; Beylergil, BertanHarnessing the potential of hexagonal boron nitride (h-BN) in epoxy composites for tailoring thermal conductivity is a promising avenue in materials science. However, achieving balanced enhancements in both in-plane and through-plane directions remains a challenge that requires innovative solutions. The primary objective of this research is to evaluate how thermal and mechanical characteristics of an epoxy matrix are affected by the size and amount of h-BN particles. To achieve this goal, h-BN particles with varying sizes (micro and nano) are incorporated into the epoxy matrix at different weight ratios spanning from 0.5 wt % to 20 wt % using a pre-dispersion technique. The epoxy composites reinforced with h-BN through a molding process exhibits enhanced mechanical and thermal performance in contrast to the pristine epoxy material. During the flexural test, acoustic emission data is collected to identify the initiation and progression of damage within the specimens under testing conditions. The most notable enhancement in thermal conductivity is observed when incorporating 20 wt% of micron-sized h-BN particles. This leads to a remarkable 107% increase in the in-plane direction and an impressive 112% increase in the through-plane direction. These results can be attributed to the formation of a three-dimensional thermally conductive network by the larger h-BN particles, which extends the path of phonon scattering. Furthermore, there are significant improvements in both flexural modulus and tensile modulus. Epoxy composites containing 10 wt% of micron-sized h-BN experiences an approximate 42% increase, while those with 20 wt% of the same particles displays a substantial 47% rise in these properties. This study effectively addresses the challenges associated with tailoring the thermal properties of epoxy composites, opening up new opportunities for applications in various industries, including electronics, aerospace and thermal management systems. Graphical AbstractÖğe A comprehensive statistical evaluation of shear and peel stresses in adhesively bonded joints(Yildiz Technical University, 2024) Beylergil, BertanThis study presents a detailed analysis of shear and peel stresses in adhesively bonded single lap joints using the Goland and Reissner analytical model. The investigation evaluates the effects of key parameters, including adhesive thickness, adhesive material, adherend material, and overlap length on stress distribution. A General Linear Model (GLM) and Analysis of Variance (ANOVA) are used to assess the significance of each factor. Results show that adhesive thickness contributes 36.55% to shear stress variation, followed by adhesive material (31.08%) and adherend material (25.83%). For peel stress, adhesive thickness accounts for 38.01% of the variation. A second-order polynomial regression model is employed to capture non-linear relationships between the input parameters and stress outcomes. The predicted shear stress of 8.676 MPa closely matches the actual value of 8.64 MPa, with a relative error of 0.42%, while the predicted peel stress of 10.9901 MPa aligns with the actual value of 11.04 MPa, with a relative error of 0.45%. The analysis highlights that thinner adhesive layers lead to higher stress concentrations, while thicker layers distribute stress more effectively. The choice of adhesive material and adherend material also significantly impacts stress levels. The study concludes that optimizing adhesive thickness, material selection, and overlap length is essential for improving the performance and reliability of adhesively bonded joints. The polynomial regression model successfully captures the non-linear stress behavior, offering a robust tool for predicting joint performance.Öğe Characterizing damage evolution of CF/PEKK composites under tensile loading through multi-instrument structural health monitoring techniques(Elsevier Sci Ltd, 2023) Yildirim, Ceren; Tabrizi, Isa Emami; Al-Nadhari, Abdulrahman; Topal, Serra; Beylergil, Bertan; Yildiz, MehmetThis study investigates the damage behavior of autoclave consolidated carbon fiber/Polyetherketoneketone (CF/ PEKK) laminates manufactured by the automated fiber placement (AFP) lay-up process. The damage evaluation of autoclave consolidated samples is studied using a multi-instrument nondestructive monitoring approach. The effect of autoclave consolidation on the microstructure of the laminate is examined via void analysis based on density measurement, thermal analysis, and optical microscopy. The results reveal that the void content is achieved as 0.46% and there is 81.81% increase in the degree of crystallinity following the autoclave consolidation. Moreover, acoustic emission (AE), digital image correlation (DIC), and infrared thermography (IRT) results are cross-correlated to further understand the damage development. The evolution of clustered AE data during mechanical loading is used to divide the failure of the laminate into two stages, each of which signifies a different dominancy in failure modes. Scanning electron microscopy (SEM) is employed to associate damage characteristics with failure monitoring techniques.Öğe Coupled Dimensional Energy Balance and Machine Learning Validation for Ballistic Response Prediction of Fiber Composites(Korean Fiber Soc, 2025) Beylergil, Bertan; Ulus, Hasan; Yildiz, MehmetIn this study, we present a coupled, dimensional energy-balance model enhanced with machine-learning validation to predict residual-velocity curves and ballistic limits of fiber-reinforced composites. Projectile deceleration is described as a three-term balance involving strength-like, drag-like, and inertial effects, mapped to the nondimensional groups Pi(0), Pi(1), and Pi(2); closed-form and RK4 solutions yield residual velocity and regime boundaries (Pi(0) = Pi(1), Pi(1) = Pi(2)). Validation against six literature datasets (CFRP and aramid laminates; Vr-V0 curves) shows high accuracy: median R2 = 0.93-0.96 and typical RMSE = 10-30 ms(-)1, with best case R2 = 0.976 and RMSE = 6.99 ms(-)1 for thin CFRP. Ballistic-limit predictions accurately capture the nonlinear increase with thickness, with errors less than 1 ms(-)1 in brittle CFRP and up to 10 ms(-)1 in Kevlar laminates. A global master curve of wr = Vr/V0 versus parallel to Pi parallel to 2 collapses all data and shows a consistent trend. Energy-budget analysis quantifies the contributions of the three terms: the strength term Pi(0) dominates in about 90% of operational points, while drag-like effects are minimal and inertial effects only appear at thick or high-velocity limits; the dominance fractions and combined contributions support these shifts. The (V-0,h) regime map, derived by setting Pi(0) = Pi(1) and Pi(1) = Pi(2), separates design-relevant domains and aligns with observed transitions in Vr-V0 modes and slopes. An independent machine-learning check using Random Forests achieves R2 = 0.992, RMSE = 17.5 ms(-)1, and MAE = 12.4 ms(-)1 (fivefold cross-validation: R2 = 0.835 +/- 0.145), supporting the mechanistic hierarchy through feature importance. The integrated physics-based model and machine-learning analysis provide traceable parameters (alpha, beta, gamma), uncertainty bounds, and practical screening maps for composite and geometric options under high-velocity impact.Öğe Design and discrete optimization of hybrid aluminum/composite drive shafts for automotive industry(Academic Publication Council, 2021) Beylergil, BertanFiber reinforced composites have been widely used in automotive industry since they offer significant weight reduction, low manufacturing and tooling cost, and better integration of parts compared to metal counterparts. In this study, design optimization of a hybrid aluminum/composite drive shaft subjected to torsion was carried out using ANSYS Workbench with ACP module. The numerical validation of finite element (FE) model was carried out by means of theoretical, experimental, and numerical studies in the literature. The ply material, lay-up orientations, and thickness of aluminum layer were considered as design variables. The geometric parameters in design were the length and inner diameter of the drive shaft. Two important design constraints, the minimum first mode natural frequency and design torque, were considered to satisfy the design requirements of a rear-wheel drive shaft used in automotive industry. The optimum design variables were determined by using screening method. The optimum design parameters (length, inner diameter, ply angle, and material) were presented in tabular form. Compared to nonoptimized scenario, the optimized solution reduced the cost of the hybrid composite drive shaft about 30% without ignoring the design requirements.Öğe Design of Highly Thermally Conductive Hexagonal Boron Nitride- Reinforced PEEK Composites with Tailored Heat Conduction Through-Plane and Rheological Behaviors by a Scalable Extrusion(Amer Chemical Soc, 2023) Gul, Saher; Arican, Selin; Cansever, Murat; Beylergil, Bertan; Yildiz, Mehmet; Okan, Burcu SanerThe challenge of developing highly thermally conductive polymeric composites to meet the growing thermal management demands has recently attracted a lot of attention. To achieve a through-plane thermal conductivity higher than 2 W/mK, a high filler concentration within the poly(ether ether ketone) (PEEK) matrix is required, thus adding to the complexity of polymer processing. In this study, an optimized twin-screw extrusion melt compounding technique was developed by tuning the melt flow of unfilled PEEK, feeding zones, and process cycles for dispersion of hexagonal boron nitride (h-BN) in the PEEK polymer. The prepared composites demonstrated exceptionally high in-plane and through plane thermal conductivity of 12.451 and 2.337 W/mK, respectively, at 60 wt % h-BN loading. This improvement of thermal conduction in both directions can be attributed to two factors: (1) formation of through-thickness surface contacts between h-BN particles due to shear-driven exfoliation during compounding stage and (2) high degree of alignment of h-BN platelets achieved during molding stage. The calorimetric and thermogravimetric analyses indicated that the prepared composites possess enhanced crystallinity compared to unfilled PEEK and are thermally stable in elevated temperature ranges. The rheological characterization exhibited a progressive increase in viscosity and shear-thinning behavior of composite melts proportional to the h-BN concentration. Using the temperature and time-dependent rheological results, viscosity buildup profiles were constructed to outline allowable melt viscosity ranges for each composite composition. These profiles can be utilized to tailor the residence time of a composite melt by varying the filler concentration and process temperature during advanced manufacturing processes such as extrusion-based additive manufacturing and powder bed fusion. Hence, we provide a facile and industrially scalable method for development of h-BNfilled PEEK composites with high thermal dissipation characteristics aimed for thermal management in various harsh environment applications.Öğe Effect of atmospheric plasma treatment on Mode-I and Mode-II fracture toughness properties of adhesively bonded carbon fiber/PEKK composite joints(Pergamon-Elsevier Science Ltd, 2023) Yildirim, Ceren; Ulus, Hasan; Beylergil, Bertan; Al-Nadhari, Abdulrahman; Topal, Serra; Yildiz, MehmetThis study aims to assess the influence of peel-ply (PP), mechanical abrasion (MA), and atmospheric plasma activation (APA) treatments on Mode-I and Mode-II fracture toughness of carbon fiber/ poly-ether-ketone-ketone (CF/PEKK) composite joints. A comprehensive examination of the topography and wettability of the adherend surfaces is conducted using various methods. The CF/PEKK adherends are produced through an automated fiber placement (AFP) process, and the CF/PEKK bonded joints are prepared using two different structural adhesive films, one of which has a lower strength, while the other has a higher strength. To evaluate their fracture toughness properties, double cantilever beam (DCB) and end-notched flexure (ENF) tests are carried out in accordance with ASTM standards. Acoustic emission sensors are used to monitor the test specimens during DCB tests, allowing for an in-depth evaluation of the failure modes and damage propagations in the joints. The results show that the GIC and GIIC values of the APA-treated CF/ PEKK bonded joints are remarkably higher than those of the untreated ones, with a range of improvement of 34.0-84.8 times and 7.5-17.4 times, respectively. Adhesive failure is the dominant failure mode on the surfaces of non-treated (NT) and PP samples, while cohesive failure is more prominent in those treated with MA and APA. The failure modes of the treated samples varied depending on the adhesive used, with APA-treated samples always exhibiting a cohesive failure. It is observed that the AE counts increase more slowly in APA-treated samples compared to MA-treated joints as delamination progresses more slowly with cohesive failure dominant, which leads to a lower release of AE energy.Öğe Effect of nanomaterials/nanofibers on the structure and properties of fiber-reinforced composites(Elsevier, 2020) Seyyed Monfared Zanjani, Jamal; Beylergil, Bertan; Poudeh, Leila Haghighi; AlKhateab, Baidaa; Mencelo?lu, Yusuf Ziya; Yildiz, M.In the past decade, there has been a dramatic increase in the production and application of nanoengineered materials in general and polymeric nanocomposites in particular. These nanomodified composites attracted considerable interest in many applications including wind turbines, automotive, and aeronautics due to their strength, rigidity, lightweight, and potential multifunctionality. This chapter focuses on the nanoengineered fiber-reinforced polymeric composites. The aim is to present and collect the results of published studies with a specific focus on the mechanical response of nanoengineered fiber-reinforced composites and identify new trends in this area. Different nanomaterials, including nanoparticles and nanofibers, with high potentials to enhance the mechanical properties of fiber-reinforced composites are introduced covering their synthesis, processing, integration methods, and resulting mechanical and physical properties. © 2020 Elsevier Inc. All rights reserved.Öğe Effects of silane-modified nano-CaCO3 particles on the mechanical properties of carbon fiber/epoxy (CF/EP) composites(Wiley, 2023) Durukan, Seyma Nur; Beylergil, Bertan; Dulgerbaki, CigdemIn this study, the effects of silane-treated nano-CaCO3 particles on the flexural, Mode-I, Mode-II and interlaminar shear strength (ILSS) properties of carbon fiber/epoxy composites are investigated experimentally. The surface of nano-CaCO3 particles is treated with a silane coupling agent, namely, (3-Glycidyloxypropyl) trimethoxysilane (GPTMS). Three-point bending, double cantilever beam (DCB), end-notch flexure (ENF), and short beam shear (SBS) tests are carried out on the prepared composite specimens according to the relevant ASTM requirements. The results show that with the dispersion of 5 wt% silane-treated nano-CaCO3 particles the flexural modulus, flexural strength, Mode-I fracture toughness, Mode-II fracture toughness, and ILSS values can be enhanced by 16.8%, 13.6%, 25.7%, 19.6%, and 19.8%, respectively, compared to reference composites. The storage modulus is also increased by about 15.3% with the silane-treated nano-CaCO3 particles. The silane-treated nano-CaCO3 particles had no significant effect on the glass transition temperature of the composites.Öğe Engineering interfacial thermal transport through comparative analysis of electrospraying and dip coating of silanized h-BN for thermo-mechanical enhancement of CF/Epoxy composites(Elsevier Sci Ltd, 2025) Mehdipour, Mostafa; Dogan, Semih; Tabrizi, Arvin Taghizadeh; Bafqi, Mohammad Sajad Sorayani; Beylergil, Bertan; Yildiz, Mehmet; Okan, Burcu SanerThe inherently low thermal conductivity of carbon fiber (CF) reinforced epoxy composites is mainly due to porosity and fabrication defects that interrupt thermal pathways. This study demonstrated a pathway to control heat in both out-of-plane and in-plane directions by incorporating hexagonal boron nitride (h-BN) as a thermally conductive agent and by configuring interface interactions on the CF and within the epoxy resin while evaluating physical and chemical interactions. Two integration techniques of dip coating and electrospraying were employed to apply h-BN, effectively creating robust h-BN layers on CF and dispersing neat or silane-modified hBN within the epoxy matrix by combining vacuum bag and hot compression processes to reduce void content. Electrospraying silane-modified h-BN onto carbon fiber, together with incorporating 20 wt% silane-modified hBN into the matrix, resulting in a total loading of 11 wt% in the composite-led to the highest out-of-plane thermal conductivity of 1.3 W/mK, representing a 166 % increase compared to CF reinforced into epoxy composite (CF+/ EP) with the out-of-plane thermal conductivity of 0.49 W/mK. Mechanically, the configuration using neat h-BN in both the matrix and dip-coated CF achieved a 127 % increase in flexural modulus and a 49 % improvement in Charpy impact strength versus unfilled CF/epoxy composites. Resizing the CF improved directional thermal conductivity in CF/epoxy composites by controlling porosity, achieving approximately an 81 % reduction in porosity when using silanized h-BN.Öğe Enhancement of mechanical properties of carbon fiber epoxy composites using methylmethacrylate-butadiene-styrene (MBS) core-shell nanoparticles(Sage Publications Ltd, 2025) Beylergil, Bertan; Ozturkmen, Mahide Betul; Al-Nadhari, Abdulrahman; Yildiz, Sema; Aydogan, Berkay; Yildiz, MehmetThis work investigates the use of readily dispersed methylmethacrylate-butadiene-styrene (MBS) core-shell nanoparticles to improve the mechanical properties of carbon fiber epoxy (CF/EP) composites. Through the vacuum-assisted resin transfer molding (VARTM) process, CF/EP composites were manufactured with varying MBS particle loadings from 1 wt. to 7 wt. %. The mechanical properties of the composites were determined via three-point bending, Charpy impact, short-beam shear, and Mode-I fracture toughness tests, adhering to the relevant ASTM standards. The results show that the addition of MBS particles significantly increased Mode-I interlaminar fracture toughness (GIc), with the highest increase observed at 7 wt. % particle loading, demonstrating a nearly 177% improvement over the reference composite. The flexural modulus of composites slightly decreased with 1 wt. % MBS nanoparticles, indicating increased flexibility, while a synergistic effect at 7 wt. % MBS enhanced stiffness and structural reinforcement. The incorporation of MBS nanoparticles in CF/EP composites also enhanced Charpy impact strength and damping properties, with the highest impact strength observed at 7 wt. % MBS. Higher MBS content reduced the storage modulus, while the glass transition temperature remained relatively unchanged.Öğe Enhancing directional thermal conductivity in hexagonal boron nitride reinforced epoxy composites through robust interfacial bonding(Wiley, 2025) Mehdipour, Mostafa; Dogan, Semih; Hezarkhani, Marjan; Dericiler, Kuray; Arik, Muhammet Nasuh; Yildirim, Cennet; Beylergil, BertanEstablishing a robust interfacial bond between hexagonal boron nitride (h-BN) plates and the epoxy matrix is essential for enhancing heat transfer, which is difficult because of h-BN's low-surface energy, tendency to clump together, and the chemical inertness of the epoxy matrix. This research shows different techniques for treating the surface of h-BN fillers by applying acids and thermal processes to activate the surface. The silanization process was used to increase the silane content on the surface of activated h-BN in order to make it more compatible with the epoxy matrix. X-ray photoelectron spectroscopy analysis revealed silicon peaks (Si2s peak at 150.1 eV and Si2p peak at 100.3 eV) in the spectrum of silane-treated samples. Heat treatment resulted in the production of more oxygen molecules on the shell of h-BN compared to the acid treatment. Here, the primary focus was on examining how surface treatment affects thermal conductivity (TC) performance in both in-plane and through-thickness paths. There was an increase in the epoxy's TC perpendicular to the plane, going from 0.21 to 0.47 (W/mK), showing a remarkable 123.8% enhancement by adding 10 wt% of silane-modified-thermal treated h-BN particles. The improvement resulted from effectively silanizing the exterior boundary of h-BN particles, enhancing connection and distribution in the epoxy matrix. Surface modification of h-BN-epoxy composites improves TC, leading to better heat conduction in thermal management systems, benefiting industries like aerospace, automotive, and energy systems.Highlights Silanization of h-BN for better filler-matrix bonding leading to improved heat transfer Boosting thermal conductivity in the through-thickness direction with surface-modified h-BN Significant improvement in through-thickness thermal conductivity with treated h-BN. Thermal treatment of h-BN produced better oxygenation than acid treatment. Application in aerospace and automotive through improved heat transfer. h-BN functionalization route for higher thermal conductivity. imageÖğe Enhancing Mode-I and Mode-II fracture toughness of carbon fiber/epoxy laminated composites using 3D-printed polyamide interlayers(Sage Publications Ltd, 2024) Beylergil, Bertan; Duman, VolkanDelamination is a critical concern in laminated composites, affecting their structural integrity and overall performance. This study investigates the enhancement of Mode-I and Mode-II fracture toughness in carbon fiber/epoxy (CF/EP) composites through the incorporation of 3D-printed polyamide (PA) interlayers. Vacuum-assisted resin transfer molding was utilized to fabricate composite laminates with and without 3D-printed PA interlayers. Comprehensive testing was conducted to assess the effect of 3D-printed PA interlayers on the Mode-I and Mode-II fracture toughness, interlaminar shear strength, and flexural properties, as well as thermomechanical response using dynamic mechanical analysis. The results revealed a significant improvement in critical energy release rates for both Mode-I and Mode-II (GIc and GIIc), increasing by 43.5% and 81.2% respectively, compared to the reference composites. This enhancement was primarily attributed to crack bridging and plastic deformation of PA filaments in the interlaminar region. Additionally, interlaminar shear strength increased by 17.4%. While the reference composites had a glass transition temperature of 117.3 degrees C, the PA-reinforced composites showed a slightly higher value at 119.6 degrees C, with no significant change in the glass transition temperature. tan delta max values increased from 0.321 to 0.576, suggesting better energy dissipation in PA-reinforced composites. However, flexural properties were adversely affected by the increased thickness and reduced fiber volume fraction due to the introduction of 3D-printed PA interlayers, with the flexural modulus decreasing by approximately 28% and the flexural strength by around 50%. These findings offer promising opportunities to enhance the performance of CF/EP composites under specific loading scenarios, thus expanding their potential applications across diverse industries.Öğe Experimental and statistical analysis of carbon fiber/epoxy composites interleaved with nylon 6,6 nonwoven fabric interlayers(Sage Publications Ltd, 2020) Beylergil, Bertan; Tanoğlu, Metin; Aktaş, EnginThermoplastic interleaving is a promising technique to improve delamination resistance of laminated composites. In this study, plain-weave carbon fiber/epoxy composites were interleaved with nylon 6,6 nonwoven fabrics with an areal weight density of 17 gsm. The carbon fiber/epoxy composite laminates with/without nylon 6,6 nonwoven fabric interlayers were manufactured by VARTM technique. Double cantilever beam fracture toughness tests were carried out on the prepared composite test specimens in accordance with ASTM 5528 standard. The experimental test data were statistically analyzed by two-parameter Weibull distribution. The results showed that the initiation and propagation fracture toughness Mode-I fracture toughness of carbon fiber/epoxy composites could be improved by about 34 and 156% (corresponding to a reliability level of 0.50) with the incorporation of nylon 6,6 interlayers in the interlaminar region, respectively. The results also revealed that the percent increase in the propagation fracture toughness value was 67 and 41% at reliability levels of 0.90 and 0.95, respectively.Öğe Experimental failure analysis and mechanical performance evaluation of fiber-metal sandwich laminates interleaved with polyamide-6,6 interlayers through the combined usage of acoustic emission, thermography and microscopy techniques(Sage Publications Ltd, 2020) Beylergil, Bertan; Tabrizi, İsa E.; Zanjani, Jamal S. M.; Saeidiharzand, Shaghayegh; Poudeh, Leila H.; Yıldız, MehmetFiber-metal laminates are hybrid sandwich composite structures made of thin metallic sheets and layers of fiber-reinforced plastics. In this study, for the first time, the effects of polyamide 66 nonwoven interlayers on the tensile, three-point bending, interlaminar shear strength, and low velocity impact responses of fiber-metal laminates are investigated by coupling acoustic emission, thermography, and microscopy techniques. The fiber-metal laminates are interleaved with polyamide 66 nonwoven fabrics at two different areal weight density, namely, 17 gsm (grams per square meter) and 50 gsm. The tensile, bending, interlaminar shear strength, and low velocity impact tests are carried out in accordance with the ASTM standards. During the tensile and flexural tests, acoustic emission data are collected to understand damage types occurring under various loading conditions and, in turn, clearly shed light on the performance of polyamide 66 for interfacial strengthening in fiber-metal laminates. The results of acoustic emission investigation are correlated with the optical and scanning electron microscope-based microscopic analysis. It is shown that the interlaminar shear strength of fiber-metal laminates can be increased significantly (about 42%) by using polyamide 66 nonwoven interlayers. The impacted fiber-metal laminate specimens are examined to determine damage area and length using the lock-in thermography method. It is found that the polyamide 66 interlayers decrease the debonded length and damaged area up to 39 and 32%, respectively. The tensile and flexural strength and modulus of the fiber-metal laminate are not significantly affected by the presence of polyamide 66 interlayers, except a negligible drop in the value of tensile and flexural strength by 6 and 4%, respectively. The polyamide 66 interlayers are proved to be very successful in enhancing plastic deformation ability of the matrix and bonding efficiency between aluminum and composite sections.Öğe Experimental validation and numerical modeling of interfacial effects in silanized hexagonal boron nitride (h-BN) reinforced epoxy composites by tailoring silane concentration(Taylor & Francis Ltd, 2025) Mehdipour, Mostafa; Beylergil, Bertan; Yildiz, Mehmet; Okan, Burcu SanerThis study investigates the use of h-BN particles as fillers, focusing on tailoring surface chemistry to enhance the thermal conductivity of epoxy composites. By enriching the interface between h-BN particles with amino-silane groups and the epoxy matrix through controlled surface modification, thermal performance, and interfacial bonding were improved. To achieve a high degree of functionalization, h-BN particles were oxygenated to 13.6 atomic percent (at. %) through thermal treatment, followed by reduction using 3-amino-propyl-3-ethoxy-silane (APTES), which increased the amino content by 3.5% at. % under optimized reaction conditions. During composite manufacturing, 10 wt.% functionalized h-BN particles were reinforced into the epoxy matrix, increasing bulk thermal conductivity by 53%, from 0.2 W/mK to 0.34 W/mK. Heat flux simulations with ANSYS confirmed the interface interactions and thermal performance, with silanized h-BN achieving the highest heat flux of 70 W/mm2, aligning well with experimental results. While silanization improved thermal conductivity by strengthening interfacial bonding between h-BN and the epoxy matrix, it introduced brittleness, making the composites stiffer and more fragile. However, the silanized h-BN composite showed a 57.14% increase in toughness compared to neat h-BN, while the highest flexural modulus of 4126 MPa was achieved with neat h-BN.Öğe Free vibration and torsional buckling analysis of E- Glass/epoxy composite shafts with Polyamide-6,6 (PA 66) Nanofiber interlayers(2018) Beylergil, BertanIn this study, the effects of polyamide-6,6 (PA 66) nanofibers on the free vibration and torsional buckling of fourlayered E-glass/epoxy composite drive shaft were investigated numerically. The numerical analyses were carried out by using ANSYS 16.2 software package. Three different nanofiber areal weight densities (AWDs), 8, 10 and 12 g/m2, were considered to reveal the relationship between the amount of nanofibers in the interlaminar region and natural frequencies/critical torsional buckling loads. The numerical results showed that the PA-66 nanofibers had a positive effect on natural frequencies and torsional buckling load of E-glass/epoxy composite shaft. The natural frequencies and buckling load of the composite shaft can be increased by about 10 % and 22% using PA 66 nanofibers as the secondary reinforcing material in the interlaminar region. The failure torque values were not significantly affected with the inclusion of PA 66 nanofibers in the interlaminar region.Öğe Free Vibration and Torsional Buckling Analysis of E- Glass/Epoxy Composite Shafts with Polyamide-6,6 (PA 66) Nanofiber Interlayers(2018) Beylergil, BertanIn this study, the effects of polyamide-6,6 (PA 66) nanofibers on the free vibration and torsional buckling of fourlayered E-glass/epoxy composite drive shaft were investigated numerically. The numerical analyses were carried out by using ANSYS 16.2 software package. Three different nanofiber areal weight densities (AWDs), 8, 10 and 12 g/m2, were considered to reveal the relationship between the amount of nanofibers in the interlaminar region and natural frequencies/critical torsional buckling loads. The numerical results showed that the PA-66 nanofibers had a positive effect on natural frequencies and torsional buckling load of E-glass/epoxy composite shaft. The natural frequencies and buckling load of the composite shaft can be increased by about 10 % and 22% using PA 66 nanofibers as the secondary reinforcing material in the interlaminar region. The failure torque values were not significantly affected with the inclusion of PA 66 nanofibers in the interlaminar region.Öğe Hoop Strength Optimization of 3D-Printed Polylactic Acid (PLA) Rings Using Taguchi Method(Praise Worthy Prize, 2024) Beylergil, BertanUnderstanding the operational parameters that affect the strength of 3D-printed objects is fundamentally pursued in additive manufacturing. In this study, the effects of 3D printing parameters on the hoop strength of Polylactic Acid (PLA) rings are investigated, utilizing the Taguchi method for optimization. Analysis of Variance (ANOVA) is performed to uncover relationships between variables, while regression analysis is utilized to assess the compatibility of the experiments. The results show that all the 3D printing parameters are statistically significant. However, it is noted that the printing speed, temperature, and build plate temperature have a lower impact compared to infill density, which is the most important parameter on the apparent hoop strength. The most effective parameter configuration includes 100% infill density, a 65°C bed temperature, a 220°C extruder temperature, and a printing speed of 100 mm/s, resulting in a remarkable 36.1% increase in hoop strength compared to less favorable settings. Further optimization leads to an ideal combination of parameters that yields a maximum hoop strength of 48.6268 MPa, with a predictive accuracy demonstrated by a minor percentage error of 0.65% compared to the experimentally obtained value of 48.31 MPa. This research underscores the potential of Taguchi optimization in enhancing the apparent hoop strength of 3D-printed rings. The findings hold promise for optimizing FDM processes across various applications in additive manufacturing. © 2024 Praise Worthy Prize S.r.l.-All rights reserved.Öğe Influence of functionalized h-BN particle interphase and interface regulation with structural design on the directional thermal conductivity and mechanical performance of carbon fiber/epoxy composites(Elsevier Sci Ltd, 2025) Mehdipour, Mostafa; Dogan, Semih; Al-Nadhari, Abdulrahman; Bafqi, Mohammad Sajad Sorayani; Beylergil, Bertan; Yildiz, Mehmet; Okan, Burcu SanerThis study highlights the importance of interfacial adhesion between carbon fiber (CF) and the epoxy matrix by adopting a novel approach that combines untreated and silane-treated h-BN in a multilayered structure. The interface was engineered by electrospraying h-BN particles, while the interphase was modified by incorporating up to 20 % h-BN into the epoxy matrix. The highest out-of-plane thermal conductivity of 2.31 W/mK, a 116 % increase compared to the reference value of 1.07 W/mK, was achieved by sizing CF with silanized h-BN through electrospraying, in conjunction with the 20 % h-BN-loaded epoxy matrix. Conversely, the incorporation of h-BN in the epoxy alone resulted in the best mechanical performance, with approximately a 46.4 % increase in elastic modulus, a 105 % improvement in flexural modulus, and a nearly 5 % increase in Charpy impact strength. Based on CT scan results, the resizing of CF fabrics improved directional thermal conductivity in CF/epoxy composites with controlled porosity.
