方榫接合強度之研究（二）－榫頭尺寸對暗榫接合強度之影響

Studies on the Strength of Mortise and Tenon Joints (II)-The Effect of Joint Geometry Parameters on the Strength of Blind Mortise and Tenon Joint

楊明津(Ming-Jin Yang) ； 林東陽(Tong-Yang Lin)

《林產工業》 5卷3期 (1986/09) Pp. 21-30

摘要

本研究分為A、B、C三組試件進行試驗，各組試件分別以榫頭長度、榫頭寬度與標厚比等三種影響因素變化，而其它影響因素均與所設定之基準條件相同。所得結果如下：（1）根據A組與B組試驗結果顯示，暗標接合之抗彎強度與榫頭長度、榫頭寬度均成正相關。（2）根據B組試驗結果推論，暗榫接合遭受彎曲外力所造成接合面之引張合力與壓縮合力間之距離為e=0.75 TW+0.08 RW，此項假定指出下榫間高度對於暗榫接合彎曲強度之影響程度僅為榫頭寬度之1/10。因此，增加榫頭寬度可以獲致較大之抗彎強度。（3）根據C組試驗結果顯示，暗榫接合之榫厚比約為1/2時具有最大之抗彎強度。因此，目前普遍採用榫厚比為1/3之情形，就木製家具最常遭受之彎曲外力而言並不理想。（4）綜合A、B、C三組試驗與第一報「嵌合度對於暗榫接合強度之影響」所得結果，假定暗榫接合強度與構件木材之縱向抗剪強度（Sx）成正比，則其抗彎強度F_4可由預測式F_4=0.076x(Sx)x(a)x(b)x(c)x(d)估計，係數a、b、c、d查表2、表3、表4與表5。

關鍵字

暗榫接合 ； 榫頭長度 ； 榫頭寬度 ； 榫厚比 ； 彎曲力矩

並列摘要

This research is divided into three parts A、B、C for testing the factors which influence the strength of mortise and tenon joints, The specimen of each group was respectively tested for its tenon length (TL), tenon width (TW) and, tenon thickness ratio (TTR). All the other factors were kept constant as specified in the test conditions. The experimental results are summarized as follows: (1) According to the results of Groups A&B, the bending strength of blind mortise were positively and tenon correlated with the tenon length (TL), and tenon width (TW).(2) We made an inference based upon the test results of Group B, the distance (e) between the tensile resultant force and the compressive resultant force due to the external bending force acting on the tenon joint was equal to 0.75 TW plus 0.08 RW. This indicated that the effect of the shoulder height on the bending strength of the joint was 1/10 of the tenon width. Therefore, an increase in the tenon width (TW) would result greater bending strength. (3) As shown in the test results of Group C, the morise and tenon joint may have maximum bending strength when the tenon thickness ratio (TTR) is 1/2. Therefore, at present, the prevailing trend of using 1/3 for tenon thickness ratio is not enough. It would not be good for the wood furniture construction which is apt to suffer the external bending force. (4) T o conclude the testing results of Group A, B, and C, report (I), the bending strength (F_4) can be predicted by the formula: F_4=0.076x(Sx)x(a)x(b)x(c)x(d ), assuming that the bending strength of blind mortise and tenon joint is direct proportional to the shear strength parallel to the grain (Sx). Please refer to Tables 2, 3, 4ε5 for coefficients a ,b, c&d.

並列關鍵字

B l i nd Mortise and Tenon Joint ； Tenon Length ； Tenon Width ； Tenon Thickness Ratio ； Bending Moment ； Forest Products Industries