音響的手法による植物の葉の弾性率の非破壊的計測

抄録

It is generally considered that plant leaves have appropriate bending stiffness for the purpose of effective photosynthesis. However, effect of lateral veins on the bending stiffness of leaves are not obvious since lateral veins don't change cross-sectional shape of leaves in contrast of a central vein. In this study, in-plane Young's moduli parallel and perpendicular to lateral veins (E_∥ and E_⊥) of leaves of Epipremnum aureum were determined by a combination of non-destructive acoustic resonance measurements and numerical analyses using finite element method. Leaves were clamped by metal plates which have oval windows and oscillated by a speaker through the windows. The bending vibrations of the leaves were measured using a laser displacement sensor and resonant frequencies were obtained using fast Fourier transform. In-plane Young's moduli parallel and perpendicular to lateral veins were determined from measured resonance frequencies, dimensions, and mass densities using finite element analyses. The in-plane elastic anisotropies E_∥/E_⊥ obtained from all the measurement areas suggested that lateral veins increase the bending stiffness of leaf laminas of Epipremnum aureum. It was also suggested that effects of primary lateral veins on in-plane Young's moduli were larger than those of secondary lateral veins.