| Summary: | 碩士 === 國立嘉義大學 === 林產科學系研究所 === 95 === Oval-end and square-end mortise and tenon joints have been commonly used in wooden furniture. The oval-end mortise and tenon joint not only has excellent performance in joint strength but also could be processed rapidly. However, the processing of the square-end mortise is slow and is often with poor precision even though the square-end mortise and tenon joint with wedge has good performance in joint strength. This study is to investigate the effect of wedge on the joint behaviors of through oval-end mortise and tenon joint. In order to understand the relations between the pull-out loads, bending moments and rigidity efficiencies with groove widths, wedge slopes and wedge spacings, wedged through oval-end mortise and tenon joint with various groove widths (3, 4, and 5 mm) and wedge slopes (1:7, 1:8, and 1:9) for single wedge, and wedge spacings (12 and 19 mm) for double wedges were used. In addition, finite element analysis was used to predict the pull-out loads and bending moments, and both were compared with the tested ones.
Except for rigidity efficiencies, the pull-out loads and bending moments of the oval-end mortise and tenon joint with single and double wedges were greater than those without wedge. The pull-out loads of the oval-end mortise and tenon joint with single wedge were increased with the increase of wedge slopes and with the decrease of groove width, and the same tendency could also be observed in the data predicted by the finite element method. The difference between the measured and predicted pull-out loads are between -2.10 and 7.47 %. The highest compressive stress and displacement were found at the uppers corners of the groove when wedge was in groove. For the oval-end mortise and tenon joint with single wedge, the highest compressive stress and displacement were found for 3 mm groove width and 1:7 wedge slope. With the same groove width and wedge slope, the pull-out loads of the oval-end mortise and tenon joint with double wedge weres greater than those with single wedge.
Rigidity efficiencies of the wedged oval-end mortise and tenon joint had no significant differences among various combinations. The maximum bending moments of the oval-end mortise and tenon joint with single wedge were also increased with the increase of wedge slopes and with the decrease of groove width. However, for the same groove widths and wedge slopes, the bending moments of the oval-end mortise and tenon joint with double, single and without wedges have no significant differences. Furthermore, the difference between the measured bending moments and the predicted ones were between -5.00 and 6.21 %. The predicted bending moments of oval-end mortises and tenon joints with shoulders were 30 ~ 38 % higher than those without shoulders. The predicted data also showed that when bending occurred on the wedged oval-end mortise and tenon joint, the stress concentration was found on the apex of the lower shoulder of the tenon. Also, the compressive stress at the apex of lower shoulder was increased with the increase of the displacement loading. According the simulation by the finite element, the pull-out loads and bending moments increased with the increase of wedge spacings in the range of 10 to 16 mm.
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