Figure 6.
Ratios of the bending moment of different failure modes as a function of t/R. (a) The dominant failure modes are Brazier buckling (Mode I), tangential cracking/longitudinal splitting (Mode II) and conventional bending failure, i.e. compression failure on the compression side and tearing on the tension side (Mode III) for 0 < t/R < 0.06, 0.06 < t/R < 0.27 and 0.27 < t/R < 1, respectively. (b) Effect of hollowness on the conventional bending failure. A hollow trunk with t/R = 0.3 can resist 76% of a solid trunk's failure bending moment. (c) Comparison of shear failure (Ms) and bending failure (Mb) versus t/R and slenderness h/R. Conventional bending failure is more dominant for trees with h/R > 10, whereas shear failure may only occur for extremely small h/R ratio and thin-walled trunk. (Trunk sketches by Da-Chang Yang).