CIVL439/W00D476 E仟 Wood Defects in Full Size Material Slope of Grain Knots Basis of Visual Strength Grading-Knots 尝 a Compression Parallel to Grain HA曰 11CIVL439/WOOD476 11 Defects in Full Size Material Slope of Grain Knots Effect of Slope of Grain on Wood Strengths Hankinson Equation 0 0.5 0.6 0.7 0.8 0.9 1.0 F/F(0) 0.0 0.1 0.2 0.3 0.4 0 10 20 30 40 50 60 70 80 90 Slope of Grain Angle (degree) (0 )sin ( ) (90 ) cos ( ) (0 ) (90 ) ( ) θ θ θ n n F F F F F D D D D + = Basis of Visual Strength Grading Basis of Visual Strength Grading - Knots Small Clear Testing Let’s Study Wood Mechanics. And Break Something! Tension Compression Shear Bending Fracture Compression Parallel to Grain