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Öğe 3D-Printed Biocomposites from Hemp Fibers Reinforced Polylactic Acid: Thermal, Morphology, and Mechanical Performance(North Carolina State Univ Dept Wood & Paper Sci, 2025) Celik, Esra; Uysal, Mesut; Gumus, Omer Yunus; Tasdemir, CagatayThermal, morphological, and mechanical properties were studied for 3D- printed biocomposites prepared from polylactic acid (PLA) and hemp fibers. For this purpose, the neat PLA, PLA/Hemp fiber (3 wt%), PLA/Hemp fiber/Maleic anhydride (3 wt% and 0.6 wt%), and PLA/Hemp fiber/Maleic anhydride/Glycerol (3 wt% and 0.6 wt% + Glycerol added in 10% of PLA) biocomposites were extruded to obtain filaments for fused filament fabrication (FFF). Thermogravimetric analysis (TGA) provided temperatures corresponding to 5%, 10%, and 90% mass losses for materials before and after 3D printing. During 3D printing, filaments were extruded with a nozzle temperature of 220 degrees C; consequently, their thermal properties worsened after 3D printing. In thermal analysis, T g increased by adding hemp fiber and maleic anhydride but was decreased with glycerol addition. The tensile and flexural strengths of neat PLA and biocomposites were not statically different, but flexural strength was slightly increased by adding ingredients one by one. Regarding modulus of elasticity (MOE) of materials, the sample group of the PLA/hemp fiber/maleic anhydride had the highest value. However, glycerol addition decreased MOE by 17%. These results showed that material performance of the PLA could be improved or remain statistically identical by adding hemp fiber, maleic anhydride, and glycerol.Öğe Analysis of cross laminated timbers with finite element method(Bursa Technical University, 2024) Karatay, Halil; Güntekin, Ergün; Uysal, MesutThe bending behavior of cross-laminated timber (CLT) under the imposed load was examined using the Finite Element Method (FEM) in the study. For this reason, the bending properties of CLTs made of Uludağ fir and black pine wood in the literature were used and compared with the study results. Specimens were modeled using ANSYS finite element software, taking into account the orthotropic material properties of the wood and the gluing used in lamination. While the load-deformation curve of the CLT made of Uludağ fir wood moved away from the linear region after imposing a load of 700 N, it moved away from the linear region after 1400 N for the CLT made of black pine wood. While the deformation under 800 N was 10.50 mm in CLTs made of Uludağ Fir wood, it was 13.85 mm in those of black pine wood. Besides, the load-deformation curves obtained from numerical analyses were compatible with the load-deformation curves in the data where the experimental results were shown. The results come into prominence in terms of the use of wood species - cut from native trees - in the wood construction industry by simulating them in a computerized environment using the orthotropic properties of black pine and Uludağ fir wood.Öğe Characterization of waste fabric fiber-reinforced wood-plastic composites(Taylor & Francis Ltd, 2025) Eksi, Basak Nur; Gulec, Aylin; Karatay, Halil; Arpaci, Emrecan; Uysal, MesutThis study aimed to explore the feasibility of incorporating waste fabric fibers into polylactic acid (PLA)-based wood plastic composites (WPCs). Unlike conventional WPC with randomly dispersed fibers, a multilayer design was employed with waste fabric fibers. Composites were fabricated by using twin-screw extrusion and then hot-pressing. Mechanical, thermal, water absorption, chemical, and morphological properties were systematically evaluated using mechanical tests, TGA, FTIR, and SEM. The multilayer configuration significantly improved strength, accordingly, advantage of a controlled reinforcement-layer design was demonstrated compared to non-reinforced sample groups. The results showed that adding 5% wood content to fabric fiber-reinforced PLA increased flexural strength by 28% and tensile strength by 24% compared to neat PLA. However, higher wood contents (10% and 15%) reduced strength by 12-18% due to poor dispersion and weak interfacial adhesion. Thermal stability improved by approximately 15 degrees C, while water absorption decreased by nearly 20% in fabric fiber-reinforced composites relative to those of higher wood content. This study demonstrated that textile waste can be successfully upcycled into high-performance, bio-based composites, providing both structural improvements and environmental benefits. These results highlight the potential of textile waste as an effective reinforcement in WPC, promoting circular economy practices and offering a sustainable alternative for various industrial applications.Öğe Coefficient of Acceptability for Joints in Furniture Frame Analysis under Cyclic Loads(2023) Uysal, MesutThis study aimed to determine the coefficient of acceptability for furniture joints on chair frames. In doing so, three chair configurations made of soft maple and yellow poplar were defined. Chairs were subjected to a front-to-back cyclic load test until non-recoverable failure occurred. Ultimate failure loads for each chair frame were used to determine the moment capacity of critical joints. Likewise, according to American Library Association, acceptable light, medium and heavy-duty service loads were subjected to chairs in the structural analysis to obtain acceptable moment capacities of critical joints, using the stiffness method. Then, lines were drawn from the initial strength of the joint to the moment capacities of the joint at the load level imposed on the chair. Differentiating the slopes between lifeline and acceptable levels gave a coefficient of acceptability. This coefficient would provide insight into the serviceability and durability of joints and chair frames.Öğe Doğu kayını (Fagus orientalis L.) kontrplak ile güçlendirilmiş yongalevha ve liflevhanın eğilme davranışının deneysel ve nümerik analizi(2024) Ergün, Güntekin; Uysal, MesutBu çalışmada, Doğu kayını (Fagus orientalis L.) kontrplak (KP) kullanılarak güçlendirilmiş yonga levha (YL) ve orta yoğunlukta liflevhaların (MDF) eğilme davranışı deneysel ve nümerik yöntemler ile incelenmiştir. Çalışmada, 13 mm kalınlığında YL ve 12 mm kalınlığında MDF levhalar 4 mm kalınlığında kontrplak levhalar kullanılarak güçlendirilmiştir. Levhaların yapıştırılmasında poliüretan tutkalı kullanılmıştır. Deney örnekleri TS EN 310’a göre üç nokta eğilme testine tabi tutularak eğilme davranışları incelenmiştir. Çalışmada ayrıca, test edilen güçlendirilmiş örneklerin sonlu elemanlar modelleri oluşturularak nümerik analizleri gerçekleştirilmiştir. Çalışma sonuçları KP kullanarak güçlendirilmiş YL örneklerin eğilmede elastikiyet modülü ve eğilme direnci değerlerinin yükleme yönüne göre iki katına kadar, MDF örneklerinde ise %44 arttığını göstermiştir. Güçlendirmenin etkinliği yükleme yönüne göre değişmektedir. Çekme gerilmesine maruz kalan yüzeylerin güçlendirilmesi basınç gerilmesine maruz kalan yüzeylerin güçlendirilmesine göre eğilme özelliklerine daha fazla katkı sağlamıştır. Eğilme testlerinden elde edilen yük-deformasyon eğrileri ile nümerik analizlerden elde edilen yük-deformasyon eğrilerinin genellikle benzer olduğu görülmüştür. Çalışma sonuçları KP kullanılarak güçlendirilmiş YL ve MDF levhaların eğilme davranışlarının sonlu elemanlar yöntemi kullanarak tahmin edilebileceğini göstermiştir.Öğe Effect of Epoxy Resin Reinforcement on Screw Withdrawal Strength of Fiberboard and Particleboard Used in Furniture Industry(Zagreb Univ, Fac Forestry, 2023) Uysal, Mesut; Tasdemir, Cagatay; Memis, DoganThe study aimed to increase the screw withdrawal strength of medium density fiberboard and particleboard used in furniture strength by using epoxy resin in the screw pilot hole. Therefore, the effects of pilot hole diameters, screw diameter, and amount of epoxy resin on screw withdrawal strength of medium density fiberboard and particleboard from face and edge were investigated. According to TS EN 13446, 50 mm x 50 mm specimens were cut from commercial medium density fiberboard and particleboard boards. A static load was applied parallel to the screw direction. The screw withdrawal strength of medium density fiberboard was higher than the screw withdrawal strength of particleboard because of its density. Besides, the screw withdrawal strength of medium density fiberboard and particleboard samples with a 3.5 mm screw diameter was higher compared to those with a 4.5 mm screw diameter. A decrease in pilot hole diameter and an increase in the amount of epoxy resin provided higher screw withdrawal strength of materials. Using 20 % epoxy resin of the volume of the pilot hole resulted in two times better screw withdrawal strength values. The study showed that a higher amount of epoxy resin, smaller pilot hole diameter, and smaller screw diameter contribute to better screw withdrawal strength of both medium density fiberboard and particleboard from the face and edge.Öğe EVALUATING DESIGN OF MORTISE AND TENON FURNITURE JOINTS UNDER BENDING LOADS BY LOWER TOLERANCE LIMITS(SOC WOOD SCI TECHNOL, 2021) Uysal, Mesut; Haviarova, EvaThis study aimed to estimate the design value for mortise and tenon joints. In this respect, the design value for static load tests was determined using lower tolerance limit methods. A lower tolerance limit value at 0.99/0.99 confidence/proportional level was chosen as a design value (199.05 N.m) to secure higher joint reliability in a furniture frame. A side frame of a simple wooden chair was theoretically analyzed to obtain internal forces acting on joints, whereas the load of 1000 N was applied in the vertical direction on the top of the front leg. A full-frame chair with mortise and tenon joints was then designed using the calculated lower tolerance limit design value. This action ensured that joints would not be overstressed when a chair is under static load while not exceeding 2000 N. By applying this method, all chairs should survive static load up to 2000 N. While performing cyclic front-to-back load test, all tested chairs met the American Library Association requirements for light-duty service load, specified for household chairs. This study demonstrates that a joint failure could be prevented under expected loads specified by the standard if the joint design value is known.Öğe Experimental and Numerical Analysis of Sandwich Panels Made of Different Core Materials with Plywood Facing(Zagreb Univ, Fac Forestry, 2025) Guntekin, Ergun; Uysal, MesutSandwich panels composed of different core materials with plywood facings were analyzed using experimental and numerical methods. Particleboard (PB), fiberboard (MDF), and foam materials were used as the core of the sandwich, while beech plywood was laid as the only face material. The layers of the sandwich were adhered with polyurethane adhesive. Elasticities (E) of PB, MDF, and plywood were determined in the laboratory. The E value specified by the manufacturer for the foam was used to determine the flexural behavior of sandwich panels. Results of the study indicated that the type of core material significantly affects the bending behavior of sandwich panels with plywood facings. Sandwich panels with MDF-core were observed to be more resistant in bending compared to PB and foam-core sandwich panels. Core shear failure was the dominant failure type when wood-based materials were used as core material. Buckling or tension in facing was observed when foam was used as core material. The results of the study demonstrate that numerical models can be used to accurately predict the bending behavior of the sandwich panels until failure based on yield stress and tangent modulus of the materials.Öğe Experimental and numerical analysis of the bending behavior of beech (Fagus orientalis L.) plywood-reinforced particleboard and fiberboard panels(DergiPark, 2024) Güntekin, Ergün; Uysal, MesutIn this study, bending behavior of particleboard (PB) and medium-density fiberboard (MDF) reinforced using beech (Fagus orientalis L.) plywood (PW) was examined by experimental and numerical methods. In doing so, 13 mm thick PB and 12 mm thick MDF panels were reinforced using 4 mm thick beech plywood. Polyurethane glue was used to bond the layers. The bending behavior of the test samples was determined by subjecting them to a 3-point bending test. Finite element models of the reinforced samples tested in the study were created, and numerical analyses were performed. The results showed that the modulus of elasticity under bending and bending strength of PB samples reinforced using PW increased up to two times, and in MDF samples increased by 44%, depending on the loading direction. The effectiveness of reinforcement varies depending on the loading direction. Reinforcing the surfaces exposed to tensile stress contributed more to the bending properties than the surfaces exposed to compressive stress. Generally, it was shown that the load-deformation curves obtained from bending tests and the load-deformation curves obtained from numerical analysis are similar. The study results showed that the bending behaviors of PB and MDF reinforced using PW can be predicted using the finite element method. © 2024, DergiPark. All rights reserved.Öğe Hybrid Layer Thickness Configurations for Enhanced Mechanical Performance and Energy Efficiency FDM-Printed PLA(Bursa Teknik Üniversitesi, 2025) Uysal, MesutThis study examines the impact of hybrid layer thickness configurations on the mechanical properties and energy consumption of 3D-printed polylactic acid (PLA) parts produced via Fused Deposition Modeling (FDM). PLA specimens with various combinations of outer and core layer thicknesses (0.08 mm, 0.16 mm, and 0.28 mm) were fabricated and tested for tensile strength, flexural strength, and flexural modulus, alongside measurements of energy consumption. The results revealed that hybrid structures incorporating 0.16 mm face layers and 0.08 mm core layers exhibited superior mechanical performance. In contrast, thicker core layers (0.28 mm) significantly reduced printing time and energy use. The highest tensile strength (53.57 MPa), flexural strength (90.68 MPa), and flexural modulus (2898.4 MPa) were obtained in the sample group of 0.16_0.08_0.16 mm layer thickness. Scanning Electron Microscopy (SEM) provided microstructural insights supporting these findings. The porosity and higher nozzle temperature may influence the material strength for thicker and thinner layer thicknesses, respectively. The sample group with the least energy consumption was 0.28 mm, followed by the sample group with the same layer thickness in both the face and core layers. The study highlights the potential of hybrid layering strategies to optimize performance-energy trade-offs in FDM printing, offering valuable guidance for material-efficient and functionally robust additive manufacturing.Öğe Investigation of Indoor Noise Pollution Level and Air Quality of Furniture Manufacturers(North Carolina State Univ Dept Wood & Paper Sci, 2024) Tasdemir, Cagatay; Yildirim, Yalcin; Uysal, Mesut; Angin, Naile; Ertas, MuratIndoor air quality has become a more prominent concern since the arrival of the COVID-19 pandemic. Manufacturing industries have always been prone to occupational health risks, which depend on the dynamics of the production shop floors. The furniture industry is one of these sectors with a unique work environment. Although a typical furniture manufacturing facility involves physical, chemical, and noise pollution-producing elements, this industry has been studied relatively less for indoor air quality and noise-related risks. This study investigated nine fumiture manufacturing organizations' indoor air quality and noise pollution levels through comprehensive quantitative techniques. The results of the measurements were compared against reference values set by specific guidelines to explore the degree of occupational health risk associated with the World Health Organization's (WHO) suggested levels. Repetitive measurements from five pre-designated workstations were taken at each facility. The study's results indicated that organization size and department were significant factors for PM 2.5 and HCHO parameters, while only department type was substantial for noise exposure levels. However, across all departments and organization sizes, LAeq noise levels were below the safety threshold of 85 dB(A). Most organizations presented a lack of proper use of personal protective equipment and poor ventilation across shop floors.Öğe Prediction of screw withdrawal resistance for plywood laminated panels and sandwich panels(2024) Uysal, Mesut; Ergün, GüntekinSandwich panels are favorable materials for structural or non-structural components due to durability, lightness, and longevity in service life. This study aimed to predict screw withdrawal resistance of the plywood laminated medium-density fiberboard and particleboard, and sandwich panels. In predicting the screw withdrawal resistance, withdrawal load capacity, density, and withdrawal stiffness of the materials in each layer, screw penetration depth, and screw diameter were considered. Moreover, the screw withdrawal strength of the panels was examined. Screw withdrawal tests of panels were conducted according to TS EN 13446 standard. The test results showed a proportional correlation between the density and screw withdrawal strength of the panels. The highest screw withdrawal strength was obtained for sandwich panels made of plywood and medium-density fiberboard (12.51 MPa). Furthermore, the difference between experimental and predicted screw withdrawal resistance changed from 0.20% to 24.86%. Besides, there was no statistically significant difference between the screw withdrawal strength of the top and bottom face-laminated panels. The test results showed that both face laminated panels (sandwich panels) had higher screw withdrawal strength, density, and experimental and predicted screw withdrawal resistance compared to one face laminated panels.Öğe Reliability Measurements of the Furniture Frames with Selected Joint Types(North Carolina State Univ Dept Wood & Paper Sci, 2024) Uysal, MesutThe reliability was evaluated for frame construction with mortise and tenon (MT), dowel, and non-glued and glued staple joints made of beech wood. The moment capacities of the T-shaped joints were determined under static vertical loads. The MT joint had an average moment capacity of 204 Nm, followed by dowel joints (154 Nm). In staple joints, joint strength increased after gluing. A three-seat sofa frame was defined and theoretically subjected to loads on arm rails, side rails, and back posts. Moment levels on the joint of the frame were obtained by using the stiffness method. To measure the reliability, these moment levels were assumed to be normally distributed with a coefficient of variation of 10%; accordingly, the normal distribution of the data sets was transformed into a normal standard distribution, and then, the reliability of each joint on the frame was obtained by using probabilistic approaches. MT joints were found to have the highest moment capacity and, correspondingly, the highest reliability (99.99%). Gluing the staple joints increased the strength, so their reliabilities were increased. In designing frame construction, the critical joints should be determined, and then, the joinery system with the higher reliability should be used.Öğe Some printing parameters affecting the screw withdrawal strength of materials used in joints developed in 3D printers for furniture(DergiPark, 2024) Uysal, MesutThis study examined to benchmark the screw withdrawal strength (SWS) of the 3D-printed PLA materials considering various infill patterns and ratios. SWS is one of the critical material properties for furniture joints. For this purpose, dimensions of 10 × 50 × 50 mm specimens made of PLA+ were printed according to ASTM D 6117-18. Three infill patterns (line, grid, and concentric) and four infill ratios (25%, 50%, 75%, and 100%) were used as printing parameters to construct a complete 3 × 4 factorial experiment. According to the results, line infill patterns had the highest density compared to the grid and concentric patterns for all infill ratios. Concentric infill patterns with an infill ratio of 100% (108.41 MPa) had the greatest SWS. Grid infill patterns provided higher strength at the lower infill ratios than line and concentric infill patterns. Here, diffusion for interfaces of strands affected the SWSs of the 3D-printed materials. This study would provide insight into the 3D-printed joints in the field of furniture mechanics. © 2024, DergiPark. All rights reserved.Öğe Some printing parameters affecting the screw withdrawal strength of materials used in joints developed in 3D printers for furniture(2024) Uysal, MesutThis study examined to benchmark the screw withdrawal strength (SWS) of the 3D-printed PLA materials considering various infill patterns and ratios. SWS is one of the critical material properties for furniture joints. For this purpose, dimensions of 10 × 50 × 50 mm specimens made of PLA+ were printed according to ASTM D 6117-18. Three infill patterns (line, grid, and concentric) and four infill ratios (25%, 50%, 75%, and 100%) were used as printing parameters to construct a complete 3 × 4 factorial experiment. According to the results, line infill patterns had the highest density compared to the grid and concentric patterns for all infill ratios. Concentric infill patterns with an infill ratio of 100% (108.41 MPa) had the greatest SWS. Grid infill patterns provided higher strength at the lower infill ratios than line and concentric infill patterns. Here, diffusion for interfaces of strands affected the SWSs of the 3D-printed materials. This study would provide insight into the 3D-printed joints in the field of furniture mechanics.Öğe The diagonal tensile strength of corner joints constructed with different connectors(2024) Karatay, Halil; Akbaş, Merve Fatma; Uysal, MesutThis study aimed to investigate the strength and stiffness of corner joints for case furniture in the diagonal tension test. For this purpose, joint members were constructed with medium-density fiberboard (MDF) and particleboard (PB) with minifix, butterfly, and trapeze connectors. The study also observed the role of the end distance of the connectors, which was found to be a factor in joint strength and stiffness. According to the results, joints made of MDF performed 16 to 92 % better compared to PB, considering connectors on joints, which was evident due to material properties that MDF were denser by 7.5% and more strengthfull by 177% than PB. The butterfly connectors had the highest strength and stiffness regardless of material type and end distance, followed by trapeze connectors. The joints with minifix connectors had strength and stiffness of 2-3 times lower than others. Moreover, the end distance of 75 mm provided slightly higher joint strength and stiffness compared to those of 50 mm but was not statistically significant. Consequently, butterfly connectors demonstrated markedly the highest strength and stiffness for corner joints of case furniture. Furniture made of MDF should be chosen for higher durability rather than PB.Öğe Uludağ göknarı ve karaçam odunlarından elde edilen çapraz lamine kerestelerinin eğilme özeliklerinin incelenmesi(Isparta Uygulamalı Bilimler Üniversitesi, 2022) Uysal, Mesut; Eren, Orhan; Karatay, Halil; Memiş, DoğanBu çalışmada, EUROCODE 5 kapsamına alınan yerli iğne yapraklı ağaç türlerinden uludağ göknarı ve karaçam keresteleri ve polivinil asetat (PVAc) tutkalı kullanılarak elde edilen çapraz lamine keresteler (ÇLK) malzemesinin eğilme direnci ve elastikiyet modülü incelenmiştir. 3 katmalı olarak hazırlanan ÇLK’lar 0.4 N/mm2 basınç altında 35°C sıcaklıkta 150 dk süre ile preslenmiştir. Üç nokta eğme deneyi yük-deformasyon eğrileri elde edilen hem masif Uludağ göknarı ve karaçam hem de bu malzemelerden elde edilen ÇLK’ların eğilme direnci ve elastikiyet modülü belirlenmiştir. Masif Uludağ göknarı ve karaçamın eğilme direnci 65 N/mm2 ve 83.8 N/mm2 olarak tespit edilmiştir. Bu malzemelerden elde edilen ÇLK’ların eğilme direnci ise 38.4 N/mm2 ve 64.6 N/mm2 olarak bulunmuştur. Elastikiyet modülünde ise bu değerler sırasıyla, 9093.5 N/mm2, 11068.8 N/mm2, 5273.4 N/mm2 ve 8657.0 N/mm2 olarak belirlenmiştir. Deney sonuçlarına göre karaçam odunundan elde edilen hem masif hem de ÇLK’lar göknar odunundan elde edilenlere göre daha dayanıklı olarak bulunmuştur. Çalışmanın varyans analizi de hem masif hem de ÇLK için odun türünün istatiksel olarak anlamlı bir farklılık gösterdiğini ortaya koymuştur. Sonuç olarak, yerli iğne yapraklı ağaçlarımızın EUROCODE 5 kapsamında alınması, bu malzemelerden ÇLK’ların üretilmesi ve malzemelerin mekanik özelliklerinin belirlenmesi Türkiye ahşap yapı sektöründe bu malzemelerin yapı analizinde ve yapı eleman tasarımında önemlidir.Öğe Use of lower tolerance limits for designing chair frames with round-end mortise and tenon joints(Taylor & Francis Ltd, 2025) Uysal, Mesut; Kuskun, Tolga; Smardzewski, Jerzy; Kasal, Ali; Haviarova, EvaIn this study, the reliability of the mortise-tenon (MT) joints was examined experimentally and numerically. The joint strength has been determined empirically and numerically, but the reliability of the joint does not rely on a single asset - mean and standard deviation. The prediction of its strength also refers to a single value in the future population, but tolerance limits are related to a portion of the future population. Therefore, ensuring joint reliability comes into prominence not only for empirical data but also for theoretical and numerical analysis. For this purpose, the moment capacity of the T-shaped MT joints constructed of white oak was determined, and the lower tolerance limits (LTLs) approach was used to construct confidence/proportion (gamma/beta) levels for reliability. According to the results, the moment capacity of the MT joints was 341 Nm. The LTL values at 0.95/0.95, 0.99/0.95, 0.95/0.99, and 0.99/0.99 gamma/beta levels were 231, 226, 187 and 181 Nm, respectively. The normal stresses at each gamma/beta level were calculated based on the moment capacity and tenon sizes and were compared with the finite element method (FEM). Experimental and numerical results varied from 0.3% to 13.4%. Furthermore, a side frame was imposed to a vertical load of 1000 N on the front leg, and the moment of the joint on the side rail to the back post was measured (196 Nm). The side frame was modeled on ABAQUS - FEM software - and subjected to a moment of 196 Nm on the side rail. The theoretical and numerical results of stresses on joints differed from - 4.3% to 5.8%. The study showed that the reliability value is known, and; the joints could be designed by using FEM.
