柳杉與粒片板及中密度纖維板釘接側向拉伸疲勞行為

Fatigue Behaviors of Lateral Resistance of Nail Joint among Japanese Cedar and Particleboard and Medium Density Fiberboard

蘇文清(Wen-Chin Su) ； 王怡仁(Yi-Ren Wang)

《林產工業》 19卷4期 (2000/12) Pp. 435-440

https://doi.org/10.6561/FPI.2000.19(4).4

摘要

本研究利用省產柳杉造林木為主元件而以中密度纖維板和粒片板為側元件施以單一釘接，觀測其側向拉伸在靜態與動態的行為。所用釘尺寸有N38和N50兩種，柳杉實木橫斷面為38×89mm，而側元件厚為9mm和12mm兩種，長為210mm，寬為89mm。實驗方式為先將各釘接組合施以靜態載重至破壞，記錄其破壞載重，然後再針對N38和9mm厚側元件的接合施以拉伸疲勞試驗，拉伸疲勞試驗的載重基準為平均靜態破壞載重的60%、70%、80%和90%，載重形式為以載重基準為波峰，零載重為波谷且頻率為3Hz的正弦波。拉伸疲勞試驗至主側元件相對位移達2mm時或達100萬次為止。在靜態方面的試驗結果，接合處的各項載重、最大滑動量及剛性在相同厚度時N50釘的接合強度均大於N38釘。而N38釘接的載重值及剛性在不同板類和不同板厚均未呈現顯著的差異。N50釘接不同板厚的破壞載重則有較明顯的差異。在動態方面，9mm中密度纖維板和粒片板以N38施以單一釘接時，在載重基準為60%、70%和80%時，試驗至100萬次時均未發現有釘子斷裂或被拔出的情形發生，而載重基準為90%時，釘子均迅速被拔出。但在80%載重基準時，中密度纖維板和粒片板側元件和柳杉主元件相對位移達2mm的次數分別為889,479次和889,962次。所以此二材料的疲勞限度可能在載重基準80%和70%之間。

關鍵字

箱用釘 ； 側向拉伸 ； 拉伸疲勞試驗 ； 柳杉 ； 中密度纖維板 ； 粒片板

並列摘要

Two by four inch domestic Japanese cedar (Cryptomeria japonica D. Don) lumber was used as the main member in this study. Medium density fiberboard and particle board were used as the side members. Main member and side member were jointed by a single box nail to test the static and the dynamic behavior in lateral resistance. Nail sizes are N38 and N50. Thickness of side member are 9mm and 12mm. All joints were statically loaded to failure to record their maximum load and other characteristics, such as slip and stiffness. The dynamic test was carried out only in the case of joint between 9mm sheathing and N38 nail. The load levels were 60%, 70%, 80% and 90% of the average static maximum load. The load function is a non-reversed 3Hz sinusodial wave with the load level as its peak value. The fatigue test was carried out until either the slip between main member and the side member reached 2 mm or test cycles reached one million. As a result, the loads, maximum slip and stiffness for the joint of N50 were always larger than the joint of N38 for the same thickness of side member regardless of the sheathing materials. The static loads and stiffnesses of N38 nail joint of both sheathing materials and thicknesses showed no significant difference. However, the static maximum loads of N50 joint had significant difference for different board thickness. The nail neither broke nor being pulled out for the joint of N38 nail and 9 mm sheathing under load levels of 60%, 70% and 80% after one million cycles. Nails were pulled out of joint quickly at load level of 90%. At load level of 80%, the cycles to reach 2mm slip for medium density fiberboard and particle board were 889,479 and 886,962, respectively. Therefore, the fatigue limit for both materials jointed with Japanese ceder might lie between load level of 70% and 80%.

並列關鍵字

Box nail ； Lateral resistance ； Fatigue test ； Japanese cedar ； Medium density fiberboard ； Particleboard