高溫乾燥 Southern Pine 옹이材의 品質

Wood Qualities of High-temperature Dried Knotty Southern Pine

This experiment was carried out to investigate the third - point edgewise bending properties of southern pines being used largely in America. The tested woods had grade controlling defect(knot) centered in span which was likely to cause faillure and were high - temperature dried. The results obtained were as follows: (1) The average width of annual ring and latewood of southern pines were 5.6mm and 30%. respectively. There was no correlation between the annual ring width and the percent-latewood. (2) The proportions of centered knot failure were 52% when knots oriented down and 32% when knots oriented up, respectively. (3) The woods with down-oriented knots had 477kg/cm2 of MOR and 25.4mm of deflection to proprotional limit, but those with up-oriented knots had 546kg/cm2 of MaR and 27.1mm of deflection to proportional limit. (4) The MOR and MOE of woods with knots decreased as the annual ring width increased and this decreasing tendency were more irregular in woods with down-oriented knots than in woods with up-oriented knots. (5) The B type of Knots (Fig. I) showed highest frequency of 75%, and the typical types of bending failures were cross grain tension and simple grain tension.