家具T型與L型構件之疲勞性質

Fatigue Life of T and L Type Furniture Joints

王怡仁(Yi-Ren Wang) ； 蘇文清(Wen-Ching Su)

《林產工業》 17卷2期 (1998/06) Pp. 277-286

https://doi.org/10.6561/FPI.1998.17(2).3

摘要

椅類家具在使用過程中或因含水率的變化而使接合處膨潤收縮，或因起坐使用而使接合處受到反覆荷重而產生疲勞現象，所以接合處的疲勞行為有了解的必要。本研究以省產杉木製作橢圓榫、木釘橢圓榫、雙木釘、單木釘螺栓及雙螺栓等五種接合方式，分別製作T型構件以求得靜態引拔荷重和L型構件求得靜態彎矩抵抗。另對橢圓榫和雙木釘接合以其靜態引拔荷重的30%、40%、50%和60%為荷重基準進行動態試驗至破壞發生達20萬次為止。荷重形式以荷重基準為波峰而0為波谷頻率為1.5 Hz的正弦波。五種靜態引拔荷重和彎矩抵抗均以雙螺栓接合為最大。在30%荷重基準時，二者試驗至25萬次均沒有破壞發生，顯示橢圓榫和雙木釘的疲勞限度應在40%和30%荷重基準之間。

關鍵字

家具接合 ； 疲勞壽命 ； 引拔強度 ； 彎矩抵抗

並列摘要

Wooden chair may cause fatigue behaviors in service either due to shrinkage and swelling caused by moisture change or due to actions such as sit down and get up. Therefore, it is necessary to study the fatigue phenomena of the joints in wooden chairs. Five joints constructed of oval-end, dowel and oval-end, two-dowel, dowel and through-bolt and two through bolts were made with China fir. Tests were carried out to determine the static withdrawal strength of T-type construction, and bending moment resistance of L-type construction. Four load levels, which are 30%, 40%, 50% and 60% of the static withdrawal strength for oval-end joint and two-dowel joint, were used in the fatigue tests. The load function is a non-reversed 1.5 Hz sinusoidal wave with the load level as its peak. The fatigue test was carried out until failure occur or test reaches 200000 cycles without failure. Static results indicated that the two-through bolts joint has both maximum withdrawal strength and bending moment resistance, The cycles to failure for both the oval-end and two dowel joints decreased with the increased load levels. The cycles to failure for the oval-end joint under 30%, 40% and 50% load levels are respectively 100700, 20571 and 1967. For the two-dowel joint, the cycles to failure are respectively 170925, 36006 and 3375 for the same load levels. Both joint types reaches 200 thousands cycles without failure at the load level of 30%. It appears that design values range from 30% to 40% of the average maximum withdrawal strength may provide base values for determining allowable design stresses.

並列關鍵字

Furniture joint ； fatigue life ； withdrawal strength ； bending moment resistance