Abstract
The effect of "bypass notch" and "uneven hinge thickness" on directional felling and job safety was observed using video recording, and was analyzed using the finite element method (FEM). Video observation showed that the hinge of trees with a bypass notch broke quickly even when the tree inclined slightly and the direction of felling could not be controlled. FEM analyses clarified that "barber chair" tended to occur and could cause accidents in the case of low backcut. Bypass notch should therefore be avoided in the case of low backcut to conserve the hinge. It was confirmed by video observation that trees with an uneven hinge thickness did not always fall in the direction of thicker hinge. FEM analyses showed that a slight right-angle displacement to the felling direction occurred when an uneven thickness hinge vented. However, the effect of the displacement on the final felling direction is not clear. To control the felling direction by changing the hinge thickness unevenly is not a reliable method in actual felling operations and is not appropriate for job safety.
