Kapaciteti posmične sile spojeva namještaja H-tipa izrađenoga od različitih toplinski tretiranih vrsta drva

The aim of this study was to investigate the effect of wood species, heat treatment, adhesive type and joint technique on shear force capacity of H-type furniture joints. For this purpose, an experimental design that consisted of 3 wood species, 2 treatment processes (untreated, heat-treated), 2 adhesive types (polyurethane (PUR), polyvinyl acetate (PVAc)) and 2 joint techniques (dowel, mortise-tenon (MT)) and 5 replications for each group were prepared, and accordingly, a total of 120 specimens were tested under static shear loads. Siberian pine (Pinus sibirica), Iroko (Chlorophora excelsa), and common ash (Fraxinus excelsior), which are commonly used in furniture constructions, were used as wood species. In general, iroko showed the highest shear force capacity between the wood species. The specimens constructed of heat-treated wood species showed lower shear force capacity by approximately 15 % in comparison to the same untreated specimens. MT joints showed better performance than dowel joints higher by approximately 21 %. PVAc adhesive gave higher values than PU adhesive by around 5 %. According to the results of four-way interactions, highest shear force capacities of H-type joints were obtained from “Common ash-PVAc-MT” combination in groups of untreated specimens and from “Iroko-PU-MT” combination in groups of heat-treated specimens.Cilj ovog istraživanja bio je ispitati utjecaj vrste drva, njegove toplinske obrade, vrste ljepila i tehnike spajanja na kapacitet posmične sile spojeva namještaja H-tipa. Za tu je namjenu pripremljen eksperiment s ovim parametrima: tri vrste drva, dvije obrade (netretirani i toplinski tretiran namještaj), dvije vrste ljepila (poliuretan – PUR, polivinilacetat – PVAc) i dvije tehnike spajanja (moždanikom te čepom i rupom – MT). Za svaki sustav pripremljeno je pet uzoraka te je pri statičkom posmičnom opterećenju ispitano ukupno 120 uzoraka. Odabrane su vrste drva koje se često upotrebljavaju u konstrukcijama namještaja: sibirski bor (Pinus sibirica), iroko (Chlorophora excelsa) i jasen (Fraxinus excelsior). Prema rezultatima istraživanja, drvo iroka pokazalo je najveći kapacitet posmične sile od svih ostalih vrsta drva obuhvaćenih eksperimentom. Uzorci izrađeni od toplinski obrađenog drva imali su oko 15 % manje vrijednosti kapaciteta posmične sile od netretiranih uzoraka. MT spojevi pokazali su za oko 21 % veće vrijednosti od spojeva s moždanicima. Uz upotrebu PVAc ljepila vrijednosti su bile za oko 5 % veće od vrijednosti s PUR ljepilom. Prema rezultatima četverosmjernih interakcija, najveći kapaciteti posmične sile spojeva H-tipa dobiveni su za kombinaciju jasenovina – PVAc – MT u netretiranim uzorcima i za kombinaciju drvo iroka – PUR – MT u toplinski tretiranim uzorcima

ÇEŞİTLİ ÖLÇÜLERDE ZIVANA KULLANILMIŞ T-TİPİ MOBİLYA BİRLEŞTİRMELERİNİN MEKANİK DAVRANIŞ ÖZELLİKLERİNİN SONLU ELEMANLAR ANALİZİ İLE BELİRLENMESİ

Çalışma, T-tipi zıvanalı mobilya birleştirmelerinin mekanik davranış özellikleri ve gerçek testlerden elde edilen verilerin bilgisayar destekli analiz verileriyle karşılaştırılmasını kapsamaktadır.Çalışmada, zıvana ölçülerinin (zıvana genişliği ve boyu) birleştirmenin mukavemeti üzerindeki etkileri incelenmiştir. Bu amaçla, 3 farklı zıvana genişliği, 3 farklı zıvana boyu ve 10 yineleme olmak üzere toplam 90 adet deney örneği hazırlanmış ve test edilmiştir. Deney örnekleri Doğu kayını (Fagus orientalis L.) odunundan üretilmiş olup, bilgisayar destekli üç boyutlu yapısal analizler ise bir sonlu elemanlar metodu yazılımı olan ANSYS Workbench programı ile yapılmıştır. Çalışmanın sonucunda, sandalye üretiminde, arka ayak–yan kayıt birleştirmelerini temsil eden T-tipi birleştirmeler için 40x50 mm (genişlik x uzunluk) boyutlarındaki zıvana en iyi sonucu vermiştir. Birleştirmelerinin elastikiyetinde zıvana genişliğinin, moment taşıma kapasitesinde ise zıvana uzunluğunun etkili olduğu anlaşılmıştır. Ayrıca, üç boyutlu yapısal analizlerin, deney örneklerinde kabul edilebilir tahmini değerler sağladığı ve mobilya mühendislik tasarımında kullanılabileceği görülmüştür

Utjecaj nanočestica cinkova oksida na vatrootpornost drvno-plastičnih kompozita

The interest in wood plastic composites (WPCs) has increased in recent years. The utilization of environmentally friendly materials has been of great significance due to the overwhelming pressure on nature. As a widely used material, plastic is, however, easily combustible due to its structure. In this study, WPCs were reinforced with zinc oxide (ZnO) nanoparticles. The effect of higher content of ZnO nanoparticles (1, 3, 5, 10 %) on WPCs thermal stability and fire performance was investigated. Thermogravimetric analysis (TGA) clearly demonstrated that nanoparticles acted as a shield, which inhibited heat transfer and increased the degradation temperature thanks to covering the surface of materials. Free radicals accelerated the thermal degradation of neat-HDPE (high-density polyethylene) by oxidative reactions, while ZnO nanoparticles reduced the degradation velocity. Moreover, the increase in nanoparticle content significantly affected the residue. The fire performance of WPCs was also investigated by the limit oxygen index (LOI) test. While neat-HDPE flamed with dripping, ZnO nanoparticles made flaming difficult for WPCs. Therefore, the LOI values increased with increasing nanoparticle content up to 28.5 %, which indicated the need for more oxygen. The improvement reached up to 54 % compared to neat HDPE. Moreover, the char forming was also improved, which helped enhance the fire resistance. The scanning electron microscope (SEM) investigation indicated that nanoparticles were well dispersed in the matrix. However, the tendency to agglomerate increased with the increase of concentration. The ability of carbonization of wood fiber surface during the combustion also contributed to improving thermal stability and fire performance.Zanimanje za drvno-plastične kompozite (WPC) posljednjih je godina poraslo. Upotreba ekološki prihvatljivih materijala ima veliko značenje zbog golemog pritiska na okoliš. Plastika je široko rasprostranjen i vrlo često upotrebljavan materijal, ali je zbog svoje strukture lako zapaljiva. U ovom su istraživanju drvno-plastični kompoziti ojačani nanočesticama ZnO. Istraživan je utjecaj većeg udjela nanočestica cinkova oksida (ZnO) (1, 3, 5 i 10 %) na toplinsku stabilnost i vatrootpornost WPC-a. Termogravimetrijska analiza (TGA) jasno je pokazala da nanočestice djeluju kao štit koji inhibira prijenos topline i povećava temperaturu razgradnje. Nadalje, slobodni radikali u reakcijama oksidacije ubrzali su toplinsku razgradnju čistog HDPE-a (polietilena visoke gustoće), dok su nanočestice ZnO smanjile brzinu razgradnje. Štoviše, povećanje udjela nanočestica znatno je utjecalo na ostatak nakon razgradnje. Vatrootpornost WPC-a također je ispitana mjerenjem graničnog indeksa kisika (LOI). Dok je čisti HDPE gorio uz kapanje, nanočestice ZnO otežale su gorenje WPC-a. LOI vrijednosti rasle su s povećanjem udjela nanočestica do 28,5 %, što je upućivalo na veću potrebu za kisikom. Poboljšanje je iznosilo do 54 % u usporedbi s čistim HDPE-om. Štoviše, poboljšano je i stvaranje pougljenjenog sloja koji je pridonio povećanju vatrootpornosti. Istraživanje pretražnim elektronskim mikroskopom (SEM) pokazalo je da su se nanočestice dobro dispergirale u matrici. Međutim, tendencija aglomeraciji povećala se s povećanjem koncentracije nanočestica. Sposobnost karbonizacije površine drvnih vlakanaca tijekom gorenja također je pridonijela poboljšanju toplinske stabilnosti i vatrootpornosti WPC-a

Integrated product engineering and performance testing of furniture

The intention of this study was to develop a comprehensive methodology that integrated rational structural design methods with performance testing to provide an effective and economical means of assuring the design of furniture products that fulfill their intended purposes in terms of structural durability, safety, and overall quality. Included with the study were the design and analysis of wood school chairs and desks based on conventional structural design methods, evaluation of the furniture by performance test equipment and procedures selected specifically for that purpose, and finally a comparison of the results obtained by performance testing with that predicted by conventional design procedures. In order to achieve the desired objectives, 16 school chairs and 12 school desks were constructed using low cost basic wood machining techniques and equipment. Round mortise and tenon joints were consistently utilized in construction of all the frames. Product engineering methodology was utilized in the design and construction of the furniture. As part of the design process, prototypes were tested utilizing the low cost performance testing equipment and the cyclic stepped increasing load method that was previously developed for library and office furniture. The prototype frames were structurally analyzed by means of Finite Element Analysis software. Results of the study showed that low cost, simple, easy to use and maintain performance testing equipment can be used for testing school chairs and desks. Furthermore, performance testing was shown to be an essential part of the design process since it provides quantitative feedback. In addition, testing allows discovery and observation of unexpected failures and provides useful insight to actual usage and failure conditions. Results also showed that three-dimensional structural analyses by means of Finite Element Analysis (FEA) provided reasonable estimates of the overall strength of the furniture constructions. In conclusion, this study demonstrated that product engineering methodology, integrating conventional structural design with performance testing is applicable to the design of wood school furniture and provides “feedback” process that ensures the integrity and “robustness” of the designs. Similar methodology can be extrapolated to other types and designs of furniture

Effect of Tenon Geometry, Grain Orientation, and Shoulder on Bending Moment Capacity and Moment Rotation Characteristics of Mortise and Tenon Joints

Bending moment capacity and moment rotation characteristics of mortise and tenon joints as a function of tenon geometry, grain orientation, length, and shoulder fit were examined. Bending moment capacity of all joints in which tenons were fully inserted in mortises was 54% greater than for joints in which tenons were not fully inserted. Jointswith 25.4-mm-long diamond-shaped tenons had greater moment capacity than either rectangular or round tenon joints, whereas joints with 38- or 51-mm-long rectangular tenons had greater capacities than jointswith diamond or round tenons. Similarly, for joints inwhich tenonswere not fully inserted, rectangular tenons had the greatest moment capacity regardless of grain orientation or length

Numerical Analyses of Various Sizes of Mortise and Tenon Furniture Joints

This study reports the moment resistance, stiffness, and numerical analysis of various sizes of round-end mortise and tenon joints. L-shaped and T-shaped specimens were constructed. Joints were manufactured using three tenon widths and three tenon lengths with 10 replications for each combination. Specimens were constructed of Turkish beech, and the joints were assembled with polyvinylacetate (PVAc) adhesive. Bending tests were carried out in compliance with accepted test methods. Numerical analyses were performed with finite element method (FEM) software. At the end of the study, the joints became stronger and stiffer as either tenon width or length increased. Tenon length had a more significant effect on moment resistance, while tenon width had a more significant effect on stiffness. Ultimate moment resistances were obtained with L-shaped joint construction of 50 × 50 mm tenons and T-shaped joint construction of 40 × 50 mm tenons. Strength of a chair could be increased by considering these results in engineering design process. Results showed that the numerical analyses gave reasonable estimates of mechanical behavior of joints. Analytical calculations and numerical simulations confirmed that the maximum stress in the glue line was concentrated at the edge and corners, and that the modeled joints had a shape-adhesive nature

Analysis of Strength, Durability, Stability, and Fatigue Parameters of Furniture Doors and Drawers Using Engineering Design Method

Mechanical behavior properties were investigated for cabinet-type cabinet doors in kitchen furniture and drawer bottoms and joints used as storage areas under load in accordance with relevant standards (BS EN 16122). In the first stage, values physical and mechanical for particle board (PB) and medium-density fiberboard (MDF) were determined. According to the test results in the second stage, it was determined that the doors assembled using a torque of 1.3 N/m in the door tests were less deformed than those assembled with 0.63 N/m. According to the finite element analysis and real test results carried out in the final stage, it has been determined that the vertical loading analysis applied on the doors coincides with the real experiments by 85%, horizontal loading by 84%, and slam shut by 50%. The doors didn’t pass the final stage durability test in real experiments, and the analysis results revealed that the deformation areas were the same as for real experiment. In the drawers; strength 85%, displacement 84%, and slam shut 94% overlap are represented. The drawers completed the durability test in real experiments, and in the analysis, it was determined that the deformation that occurred under high stresses was in the same areas

Analysis of Strength, Durability, Stability, and Fatigue Parameters of Furniture Doors and Drawers Using Engineering Design Method

Mechanical behavior properties were investigated for cabinet-type cabinet doors in kitchen furniture and drawer bottoms and joints used as storage areas under load in accordance with relevant standards (BS EN 16122). In the first stage, values physical and mechanical for particle board (PB) and medium-density fiberboard (MDF) were determined. According to the test results in the second stage, it was determined that the doors assembled using a torque of 1.3 N/m in the door tests were less deformed than those assembled with 0.63 N/m. According to the finite element analysis and real test results carried out in the final stage, it has been determined that the vertical loading analysis applied on the doors coincides with the real experiments by 85%, horizontal loading by 84%, and slam shut by 50%. The doors didn’t pass the final stage durability test in real experiments, and the analysis results revealed that the deformation areas were the same as for real experiment. In the drawers; strength 85%, displacement 84%, and slam shut 94% overlap are represented. The drawers completed the durability test in real experiments, and in the analysis, it was determined that the deformation that occurred under high stresses was in the same areas