METHOD AND DEVICE FOR MEASURING YOUNG'S MODULUS OF LUMBER

PROBLEM TO BE SOLVED: To provide a method and a device for estimating Young's modulus of lumber with a simple method.SOLUTION: On a Young's modulus and density coordinate plane, a parameter of an expression (expression of bivariate normal distribution) which indicates a probability distribution curve surface with the probability density as an ordinate axis is determined in advance from a database of Young's modulus and density of lumber. In this state, stress wave propagation speed v of measurement target lumber is determined in advance to find a straight line of E=ρvon the Young's modulus (E) and density (ρ) coordinate plane using the stress wave propagation speed. An estimation point of Young's modulus and density is determined from a peak p obtained by a curve (hereinafter referred to as an intersection curve) generated by intersection of a surface vertical to the coordinate plane corresponding to the straight line and the probability distribution curve surface. In this case, the estimation point can be determined by calculation using the expression representing the probability distribution curve surface and the expression of the straight line.SELECTED DRAWING: Figure 3 【課題】簡単な方法で木材のヤング率を推定する方法と装置を提供する。【解決手段】木材のヤング率と密度のデータベースより、ヤング率-密度座標平面上に、その確率密度を縦軸とした確率分布曲面を表す式（２変量正規分布の式）のパラメータを求めておく。上記の状態で、測定対象の木材の応力波伝播速度vを求めておき、当該応力波伝播速度より、前記ヤング率（E）-密度（ρ）座標面上のE＝ρv２の直線を求める。前記直線に対応する座標面に垂直な面と、前記確率分布曲面との交わりより生じる曲線（以下交曲線と記す）より得られるピークpよりヤング率と密度の推定点を求める。この場合、前記確率分布曲面を表す式と、前記直線の式より計算で前記推定点は求められる。【選択図】図３