Bending and fatigue strength of mortise and tenon furniture joints made from oil palm lumber

The bending and fatigue strengths of rectangular mortise and tenon furniture joints made from oil palm lumber and solid Rubberwood were compared. The results showed that the ultimate bending moment of the oil palm lumber joints were half of the strength value of Rubberwood joints. The results showed that for both materials the allowable design stresses for rectangular mortise and tenon joints could be set at 20% of its bending strength.     

Study on the strength of moltinject corner joints of furniture

An attempt was made to analyse the strength and stiffness of moltinject corner joints of cabinet furniture by comparison with that of pin dowels corner joints. The deflection of cabinet furniture whose corners were joined by the method of moltinject was predicted in this study using FEM calculations.

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Festigkeit und Steifheit von Eckverbindungen nach dem MOLTINJECT-Verfahren

Zusammenfassung Die Biegefestigkeit und Steifheit von MOLTINJECT-Eckverbindungen bei Kastenm?beln wurde untersucht und mit denen konventioneller Dübelverbindungen verglichen. Mit Hilfe der Finite-Elemente-Methode konnten die entsprechenden Biege-Elastizit?tsmodule simmliert und damit die Verbiegung der Eckverbindungen unter Last vorhergesagt werden.

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MOLTINJECT is a method for the corner joint of furniture and the samples were offered by Kurt Held GmbH.     

Load-bearing characteristics of heat-treated rubberwood furniture components and joints

The load bearing characteristics of heat-treated rubberwood furniture components and joints were studied. It was found that heat-treated samples had significantly lower fatigue strength compared to the conventionally kiln-dried rubberwood samples, which were used as control specimens. Inevitably, the recommended allowable design stresses for heat-treated rubberwood furniture components and joints could be set at 40 and 25 % of the respective bending strengths, in order to ensure its compliance with furniture performance standards. These figures are much lower than the allowable design stresses for conventionally kiln dried components, reflecting the need for a lower safety margin when working with heat-treated materials.     

Use of a resilient bond line to increase strength of long adhesive lap joints

The load capacity of long adhesive lap joints is often governed by stress concentrations at the lap ends. This paper investigates a method to minimize these stress concentrations by using a bond line with low shear stiffness and sufficient strength, here denoted as a resilient bond line. The resilient bond line is intended to increase the load carrying capacity of long lap joints by achieving a more uniform shear stress distribution while maintaining an elastic joint behaviour without damage or plastic deformation. The study comprises analytical, numerical and full-sized experimental work on double lap joints with lengths 200–700 mm comparing conventional stiff bond lines to resilient bond lines. Different resilient bonds lines were obtained by using rubber-like adhesives and by having a rubber mat within the bond line. An analytical definition of a ‘long’ lap joint is suggested and a study of adhesive-rubber bonding is also presented. The numerical analysis clearly indicates that an increase in load carrying capacity is made possible using resilient bond lines. A good agreement is also found between the numerical results and the analytical Volkersen theory, indicating that reasonable strength predictions can be obtained by hand calculations if the joint is designed in order to minimize the influence of peel stress. The experimental results of the resilient bond line verify the numerical findings, although production difficulties decrease the statistical significance of the result. On the contrary, the experimental results of the conventional bond lines significantly exceeded the numerical predictions, showing similar load carrying capacities to the resilient bond line. This is probably due to the specific boundary conditions used in the test setup. Despite some contradictory experimental results, the conclusion of this study is that the efficiency of long lap joints can be increased by the use of a bond line with low shear stiffness and sufficient strength.     

Influence of the degree of condensation of urea-formaldehyde adhesives on the tangential penetration into beech and fir and on the shear strength of the adhesive joints

The objective of this work was to evaluate the influence of the degree of condensation of urea formaldehyde (UF) resins on the tangential penetration into fir and beech and on the tensile shear bond strength of wood joints. Tangential penetration was determined by epi-fluorescence microscopy on microtome slides, exposing the bond line on a cross-sectional surface. The higher the degree of condensation (viscosity) of the resins, the lower is the possibility for penetration; beech showed higher penetration than fir. Bond strengths decreased with increased degree of condensation (viscosity) of the adhesives. Shear strength based on radial penetration was higher than for tangential penetration. The higher the penetration and the thicker, hence, the interphase, the higher was the achieved shear strength.     

碱性强弱对大豆蛋白胶黏剂胶合强度的影响

研究了碱性强弱对大豆蛋白胶黏剂胶合强度的影响。以自制的大豆蛋白胶黏剂为原料,采用2 mol/L的氢氧化钠溶液滴定分别制备不同pH大豆蛋白胶黏剂,并进行胶合强度的测定,以及红外光谱与DSC测试。结果表明:随着碱性增强,大豆蛋白胶黏剂的胶合强度呈先下降后升高再下降的趋势,pH 11时达到峰值;湿态胶合强度与干态胶合强度的变化趋势大体保持一致;不同pH大豆蛋白胶黏剂的红外图谱吸收峰位置大致未改变只是吸收强度发生改变,从而导致了胶合强度的改变;随着pH的增大,大豆蛋白胶黏剂的玻璃化转变温度先降低后升高;pH 10时玻璃化转变温度达到最低值76.55℃,pH 12时玻璃化转变温度达到最高值84.74℃。     

Effect of thickness and location of minced fat on cooking times and weight losses of composite beef joints

The effect on cooking time and weight loss of the thickness of minced fat located at the surface or centre of a cylinder of lean M. semitendinosus was examined. All joints were 160 mm longx80 mm diameter and cooked in a natural convection oven at 175°C. Joints with minced fat at the surface cooked more quickly than those with an equal thickness or volume of fat at the centre. Percentage weight losses from the joints with surface fat were greater than those from joints with the same thickness of fat at the centre but the losses were the same for joints with equal volumes of fat. Cooking time decreased and weight loss increased with increasing amounts of minced fat. For comparison, cylinders of unminced fat were also heated; these required much longer to reach 74°C and suffered substantially less weight loss than the cylinders of minced fat. This showed the need for further work to examine the effect of degree of comminution on the heat penetration and weight losses from fat.     

现代竹家具“三防”处理的研究

文中对竹结构材家具的“防霉、防腐、防蛀”处理进行研究。结合生产实践,提出适宜的处理技术,以提高竹家具品质,延长竹家具的使用寿命。     

The strength of press-glued and screw-glued wood-plywood joints

The effects of screw-gluing and gap-filling phenol resorcinol formaldehyde (GPRF) adhesive using different glue line thicknesses on the shear strength of wood-plywood joints were studied to determine the use of screw-gluing fastening (SG) method and GPRF adhesive. The specimens were manufactured using either SG method with GPRF adhesive and fine threaded drywall screws or press-gluing (PG) method with GPRF adhesive. The Analysis of Covariance (ANCOVA) was used for statistical analyses. The results showed that the strength among fastening methods was significantly affected by the glue line thickness, so the strength decreased as the glue line thickness increased. The SG fastening method was found as effective as the PG method and more effective when thick glue lines present. The method can be successfully used to bond wood to plywood for wooden panels i.e. stressed skin and sandwich panels.     

The strength of press-glued and screw-glued wood-plywood joints

The effects of screw-gluing and gap-filling phenol resorcinol formaldehyde (GPRF) adhesive using different glue line thicknesses on the shear strength of wood-plywood joints were studied to determine the use of screw-gluing fastening (SG) method and GPRF adhesive. The specimens were manufactured using either SG method with GPRF adhesive and fine threaded drywall screws or press-gluing (PG) method with GPRF adhesive. The Analysis of Covariance (ANCOVA) was used for statistical analyses. The results showed that the strength among fastening methods was significantly affected by the glue line thickness, so the strength decreased as the glue line thickness increased. The SG fastening method was found as effective as the PG method and more effective when thick glue lines present. The method can be successfully used to bond wood to plywood for wooden panels i.e. stressed skin and sandwich panels.

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Die Festigkeit von Schraub-Klebe-Befestigungen bei Holzverbindungen

Zusammenfassung Die Auswirkungen von Schraub-Klebe-Befestigung und Spaltenauffüllung mit Phenol-Resorcinol-Formaldehyd Harzen (GPRF) unter Verwendung verschieden dicker Klebefugen entlang der Scherfestigkeit der Holzverbindungen wurden untersucht, um die Verwendbarkeit der Schraub-Klebe-Verbindungsmethode und der GPRF Harze zu überprüfen. Die Proben wurden mit der SK-Methode mittels GPRF Harzen und Schrauben mit engem Gewinde oder durch Pressverleimung mit GPRF Harzen hergestellt. Zur statistischen Auswertung wurde die Analyse der Kovarianz (ANCOVA) herangezogen. Die Ergebnisse zeigten, dass die Festigkeit der Verbundsmethoden sehr stark von der Breite der Klebefugen abhängt, die Verbundsfestigkeit sinkt mit wachsender Breite der Klebefugen. Die SK-Methode erwies sich als ebenso effektiv wie die PG-Methode und als effektiver bei breiten Klebefugen. Die Methode kann erfolgreich angewendet werden, um Holz mit Sperrholz in verschiedenen Holzpanelen zu verbinden.

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改性大豆蛋白二级结构变化对其粘接强度的影响

采用不同浓度的尿素（1、3、5、8mol／L）对大豆分离蛋白进行改性,使其二级结构发生变化。测定了大豆蛋白α-螺旋、β-折叠、β-转角和无规则卷曲含量,并对二级结构含量与尿素改性大豆蛋白对木材粘接强度的关系进行了研究。结果表明,SPI对木材的粘接特性影响是十分复杂的,并不能简单地用蛋白质二级结构的含量多少来表示,同时改性SPI的抗水性也很难用其二级结构的含量来解释。因此,关于改性大豆蛋白对木材的粘接性能及其抗水性机理需要深入研究。     

Influence of glue rheology and joint thickness on the strength of bonded-in rods

The maximum pull-out strength of bonded-in rods was used for investigating the relationship between the joint geometry and the rheology of the structural adhesive. Tests with a brittle and a ductile glue type, both formulated with epoxy resins, showed that the glue rheology has a strong influence on the joint behaviour. The joint thickness is also an important parameter, having a good correlation with pull-out strength and with the fracture typology. Wood density and moisture content had a very low influence on strength, in these test conditions. A modification of the Eurocode 5 equation was developed, allowing an improved use of the adhesive properties for a safer design. Results suggest that a standardised test method for bonded-in rods would be very helpful for the determination of basic joint properties such as the maximum joint thickness and the glue strength parameter that were used in the modified design equation.     

Influence of glue rheology and joint thickness on the strength of bonded-in rods

The maximum pull-out strength of bonded-in rods was used for investigating the relationship between the joint geometry and the rheology of the structural adhesive. Tests with a brittle and a ductile glue type, both formulated with epoxy resins, showed that the glue rheology has a strong influence on the joint behaviour. The joint thickness is also an important parameter, having a good correlation with pull-out strength and with the fracture typology. Wood density and moisture content had a very low influence on strength, in these test conditions. A modification of the Eurocode 5 equation was developed, allowing an improved use of the adhesive properties for a safer design. Results suggest that a standardised test method for bonded-in rods would be very helpful for the determination of basic joint properties such as the maximum joint thickness and the glue strength parameter that were used in the modified design equation.

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Der Einfluss der Kleber-Rheologie und der Fugendicke auf die Festigkeit von Leimbindern

Zusammenfassung Die maximale Ausziehfestigkeit von verklebten Stäben wurde verwendet, um die Beziehung zwischen der Verbindungsgeometrie und der Rheologie von Bauholzklebern zu untersuchen. Tests mit einem spröden und einem duktilen Klebertyp, beide aus Epoxidharz gebildet, zeigten, dass die Kleber-Rheologie einen starken Einfluss auf das Fugenverhalten hat. Die Fugendicke ist ebenfalls ein wichtiger Parameter, der eine gute Korrelation zur Ausziehfestigkeit und mit dem Bruchbild hat. Holzdichte und Feuchtigkeit haben unter diesen Testbedingungen einen sehr geringen Einfluss auf die Festigkeit. Eine Modifikation der Eurocode 5-Gleichung wurde entwickelt, die eine verbesserte Anwendung der Klebereigenschaften für eine sicherere Konstruktion erlaubt. Ergebnisse lassen darauf schließen, dass eine standardisierte Testmethode für Leimbinder sehr hilfreich für die Bestimmung von Grundverbindungseigenschaften wäre, wie beispielsweise die maximale Fugendicke und der Kleberfestigkeits-Parameter, die beide in der modifizierten Konstruktionsgleichung verwendet wurden.

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基于ERP模式的家具生产与家具市场关系研究

本文根据ERP原理,以写字台的生产制造为例,在对ERP应用前后生产情况进行比较研究,表明ERP在市场与生产之间的均衡处理、成品库存、物料库存以及对产品可承诺量等方面有明显的效果,能使家具企业在生产上适应市场需求多变的能力得到了较大提高。     

Artificial ageing of softwood joints and its effect on internal bond strength with special consideration of flat-to-end grain joints

The effect of ageing processes on internal bond strength of three-part specimens produced from Norway spruce wood (Picea abies Karst.) bonded with one-component polyurethane (PUR), two-component emulsion polymer isocyanate (EPI), melamine-urea-formaldehyde (MUF) or phenol-resorcinol-formaldehyde (PRF) adhesive was studied. By varying the grain angle of the middle part from 0° (parallel to grain of the surface layers) to 90° (perpendicular to grain of the surface layers) in incremental steps of 10° the effect of grain direction was investigated. The specimens were exposed to a three-step ageing cycle lasting for seven days (50°C/95% relative humidity (rH), ?20°C/65?C70% rH and 75°C/15% rH) which was repeated twelve and twenty-four times, respectively. In general, a decrease in internal bond strength of the exposed specimens was observed. For all tested adhesive systems, influence of ageing processes was more pronounced for flat-to-end grain joints compared to longitudinal joints. For samples bonded with PUR adhesive strength reduction was lower compared to the other adhesives used.     

Fatigue strength and design stress of oil palm wood for?furniture?application

Oil palm wood (OPW) and oil palm empty fruit bunches based particleboard (OPEFBP) furniture components were tested on edge in order to determine their resistance to fatigue. Tests were carried out at selected stress levels that corresponded to specific percentages of the material’s ultimate strength (modulus of rupture—MOR). Generally, the materials fatigue life decreased as the levels of stress increased, and the allowable design stresses for the OPW and OPEFBP furniture components could be set at 40% of their respective MOR. The study also showed that OPW does not perform as well as solid Rubberwood in cyclic loading, but the OPEFBP showed similar fatigue performance to the conventional Rubberwood-based particleboard.     

PVC/木粉复合材料胶接件拉伸剪切强度的研究

参照国家标准GB/T 7124-2008《胶粘剂拉伸剪切强度的测定（刚性材料对刚性材料）》检测PVC/木粉复合材料胶合试件的拉伸剪切强度,发现：PVC/木粉复合材料胶合试件的断裂均发生在粘接区域外的复合材料本身,因而无法比较胶黏剂的粘接强度。为了能比较胶黏剂胶接接头的粘接强度,实验中将GB/T 7124-2008中规定的试件的厚度从1.6 mm加大至4mm。实验结果表明：采用环氧树脂粘接的PVC/木粉复合材料的拉伸剪切强度值高于用J-39丙烯酸酯胶黏剂粘接的复合材料的拉伸剪切强度。