Ojačanje spojeva između LVL elemenata polimerima ojačanim staklenim vlaknima i analiza metodom konačnih elemenata

The goal of this study was to investigate the effect of glass fiber reinforced polymer (GFRP) on joints made of laminated veneer lumber (LVL), through experimental data and evaluation by ANSYS finite element (FE) software. In order to fabricate LVL, veneer from poplar (Populus deltoides Bartr. ex Marsh) with 2.5 mm thickness and PVA adhesive were used. T-shape joints out of LVL were made and two wooden dowels were incorporated as well. Then GFRP was applied to reinforce the joints. GFRP in three grammages (100, 200 and 300 g/ m2) was adhered to joints with epoxy resin. Joints reinforcement was performed by a two-layer reinforcing agent. For comparing the effectiveness, half of the specimens were reinforced on sides and the other half on edges. Specimens were tested in static bending. The results have shown that GFRP had a significant effect on the strength of joints. Reinforced joints on both sides were stronger than those reinforced on edge. Joints reinforced with 300 g/m2 GFRP were improved by 35 % and 43 %, respectively, compared to 100 and 200 g/m2 grammage. Failure modes of specimens are dependent on GFRP grammage. The results of FE have shown that the highest concentration of stress and elastic strain was generated in the tension and compression zones of joints.Cilj rada bio je na temelju eksperimentalnih podataka i analize konačnih elemenata (FE) te uz pomoć softvera ANSYS istražiti utjecaj polimera ojačanog staklenim vlaknima (GFRP) na spojeve od lamelirane drvne građe (LVL). Za izradu LVL-a upotrijebljen je furnir drva topole (Populus deltoides Bartr. ex Marsh) debljine 2,5 mm i PVA ljepilo. Izrađeni su T-spojevi od LVL-a i ugrađena su dva drvena moždanika. Zatim je za ojačanje spojeva primijenjen GFRP u tri gramature (100, 200 i 300 g/m2) tako da je epoksidnom smolom zalijepljen na spojeve. Ojačanje spojeva izvedeno je dvoslojnim armaturnim sredstvom. Radi usporedbe učinkovitosti, polovica uzoraka ojačana je sa strane, a druga polovica na rubovima. Uzorci su ispitani na statičko savijanje. Rezultati su pokazali da GFRP ima značajan utjecaj na čvrstoću spojeva. Spojevi ojačani s obje strane bili su jači od onih ojačanih na rubu. Spojevi ojačani GFRP-om od 300 g/m2 poboljšani su za 35 % odnosno za 43 % u usporedbi s GFRP-om gramature100 i 200 g/m2. Načini loma uzoraka ovisili su o gramaturi GFRP-a. Rezultati analize konačnih elemenata pokazali su da se najveća koncentracija naprezanja i elastične deformacije pojavljuje u vlačnoj i tlačnoj zoni spojeva

Determination of Screw and Nail Withdrawal Strengths in Parallel and Perpendicular to Grain of some Hardwoods of Iran

In this study, screw and nail withdrawal strengths parallel and perpendicular longitudinal to grain of some hardwoods; oak (Quercus castaneifolia), hornbeam (Carpinus betulus), beech (Fagus orientalis), Sycamore (Platanus oriantalis) and poplar (Populus deltoids) were investigated. The tests were conducted following ASTM D 1761 with specimen dimension of 15×5×5(T×R×L). Three kinds of screws namely sheet metal screw, wood screw and coarse drywall screw with diameter of 4 and 5 mm were used. Three different nails with nominal diameter of 2.5, 3.25 and 3.75 mm were also used. The highest screw withdrawal strengths parallel and perpendicular to grain were related to hornbeam, beech, oak, Sycamore and poplar respectively. Furthermore, the highest nail withdrawal strengths parallel and perpendicular to grain were related to hornbeam, oak, beech, Sycamore and poplar respectively for nails with 3.75 mm diameter. Higher density and shear strength of hornbeam compared to the other species accounts for its high screw and nail withdrawal strengths parallel and perpendicular to grain

Investigating the Stress Carrying Capacity of Corner Joints In The Furniture Frame Fabricated With Dowel

The goal of this study was to determine stress carrying capacity of doweled corner joints in framed furniture structures. Joint members were out of European silver Fir (Abies alba) and dowels were made from Beech and Hornbeam woods as variables in this study. Diameter of dowel had three levels in size, namely 6, 8 and 10 mm. Mitered and Butted experimental joints were tested under diagonal tension and compression loads. Results have shown that stress carrying capacity of tested joints under compressive load is more than that of tension one. Also, stress carrying capacity of mitered joints, under both loading type, was more than that of butted joints. Maximum stress capacity under tension load was observed in mitered joints with dowels of hornbeam which were 8 mm in diameter. Under compressive loads, maximum stress capacity was determined in mitered joints fabricated with dowels out of beech which were 8 mm in diameter. With tension loading, changing diameter of dowels from 6 to 8 mm, stress capacity of joint did increase drastically but from 8 to 10 mm, had no significant effects on joints’ capacity. Under compressive load, changing diameter of dowels from 6 to 10 mm had significant effect on capacity of joints. Species of dowel’s wood was not effective in tension, but in compression dowels of beech wood had pronounced improvement on joints’ capacity

Establishing mathematical model withdrawal resistance of wooden dowel in plywood

The goal of this study was to investigate withdrawal resistance of doweled joint with plywood members and establishing a predicting mathematical model for such joints in which regularly dowel is installed perpendicular to surface and also edge of plywood. Joint members were out of 11-ply hardwood plywood (Hornbeam, Beech and Alder) that were 19 mm in thickness. Dowels were fabricated out of Beech and Hornbeam species. Their diameters (6, 8 and 10 mm) and depths of penetration (9, 13 and 17 mm) in joint members were chosen variable in this experiment. Results have shown that withdrawal resistance of doweled joints made on face and edge of plywood members, increases with increase of dowel’s diameter and its penetration depth. Joints made with dowels of Hornbeam had higher than dowels of Beech ones. Highest withdrawal resistances (2951 N, 2441 N) were observed in joint on face and edge side of plywood members made with dowels of Hornbeam which were 10 mm in diameter and their depth of penetration was 17 mm. Lowest withdrawal resistance values (799 N, 784N) were of Beech wood dowels which were 6 mm in diameter and 9 mm penetrated into members

Investigation on the effect of wooden dowel diameter, penetration depth and species on the bending moment resistance under diagonal tensile load of corner joints in case-type furniture

The bending moment resistance under diagonal tensile load of doweled joint in plywood members was investigated. Joint members were cut from 11-ply hardwood plywood (Beech, Hornbeam and Alder) at the nominal thickness of19 mm. Dowels were made of Beech and Hornbeam woods. Dowel diameters (6, 8 and10 mm) and depths of penetration (9, 13 and17 mm) in the joint members were selected as variables. The effect of dowel variables on the bending moment of the corner joints was evaluated. Results showed that the dowel diameter, penetration depth and species exerted a significant effect on the bending moment resistance under diagonal tensile load. Bending moment resistance under diagonal tensile load was increased as the diameter of the dowel increased from 6 to8 mmand as the penetration depth of dowel increase from 9 to13 mm. However, increasing the diameter from 8 to10 mmor the penetration depth from 13 to17 mmhad no significant effect on bending moment resistance under diagonal tensile load. Results also indicated that bending moment resistance of joints made with beech wood dowels provided higher resistance than hornbeam dowels

Investigation the bending moment resistance of joints fabricated with dowel in the case-type furniture

The goal of this study was to investigate bending moment resistance of doweled joint with plywood members. Joint members were out of 11-ply hardwood plywood (Hornbeam, Beech and Alder) that were 19 mm in thickness. Dowels were fabricated out of Beech and Hornbeam species. Their diameters (6, 8 and 10 mm) and depths of penetration (9, 13 and 17 mm) in joint members were chosen variables in this experiment. Results have shown that bending moment resistance, increases with increase of dowel’s diameter and its penetration depth. Joints made with dowels of Beech had higher resistance than dowels of Beech ones. Highest bending moment resistance (44.29 N.m) were observed in joint made with dowels of Beech which were 10 mm in diameter and their depth of penetration was 17 mm. Lowest bending moment resistance (12.08 N.m) was observed in joints having Hornbeam dowels with 6 mm diameter and 9 mm penetration

Chemical constituents of palm wastes slow pyrolysis derived vinegar

Out of rachis and stem of palm tree from grooves in humid and dry zones, test materials were randomly collected and chipped for slow pyrolysis process. Chemical constituents of a set of pyrolysis derived vinegar were identified in their aqueous phase by gas chromatograph and quantitatively compared in sampled parts of sampled tree and grooves. Another set of vinegar was dewatered by dichloromethane, then their constituents were identified by gas chromatograph coupled with mass spectrometer, chemical constituents in aqueous state in both sampled grooves were the same but with different percentage values. In the organic phase, common chemical constituents of sampled parts and grooves were quantitatively compared. In humid zone rachis was 2,22 times richer in acetic acid and 2,37 times in phenol, but in dry zone stem is richer in acetic acid by 15,35 %. In their organic phases dominant and comparable chemicals of stem and rachis from sampled zone were furfural, phenol, benzic acid, 5-methyl-2- furancarboraldehyde, butanic acid and 2-methyl-phenol. Stem from dry zone was richer in these chemicals by 36,55 %, 96,93 %, 6,37 times, 62,05, 49, 32,57 % respectively. Rachis of humid zone contained more furfural, 63,95 %, 22,08 %, 2-methyl-phenol, but that of dry zone was richer in phenol by 46,20 %, 2,5 times in benzoic acid. Results from both phases of vinegar indicate that ecological impacts on the chemical constituents of palm from the same species are evident