The twist-to-bend compliance of the Rheum rhabarbarum petiole: integrated computations and experiments.
Plant petioles can be considered as hierarchical cellular structures, displaying geometric features defined at multiple length scales. Their macroscopic mechanical properties are the cumulative outcome of structural properties attained at each level of the structural hierarchy. This work appraises the compliance of a rhubarb stalk by determining the stalk's bending and torsional stiffness both computationally and experimentally. In our model, the irregular cross-sectional shape of the petiole and the layers of the constituent tissues are considered to evaluate the stiffness properties at the structural level. The arbitrary shape contour of the petiole is generated with reasonable accuracy by the Gielis superformula. The stiffness and architecture of the constituent layered tissues are modeled by using the concept of shape transformers so as to obtain the computational twist-to-bend ratio for the petiole. The rhubarb stalk exhibits a ratio of flexural to torsional stiffness 4.04 (computational) and 3.83 (experimental) in comparison with 1.5 for isotropic, incompressible, circular cylinders, values that demonstrate the relative structural compliance to flexure and torsion.
a Department of Mechanical Engineering , McGill University , Montreal , Canada.|b Department of Mechanical Engineering , University of Manitoba , Winnipeg , Canada.
Tanvir R
TR
Faisal
c Department of Biology , McGill University , Montreal , Canada.|d Department of Cellular and Molecular Medicine , University of Ottawa , Ottawa , Canada.
Nicolay
N
Hristozov
c Department of Biology , McGill University , Montreal , Canada.
Tamara L
TL
Western
e Department of Chemical Engineering , McGill University , Montreal , Canada.
Alejandro
A
Rey
a Department of Mechanical Engineering , McGill University , Montreal , Canada.
Damiano
D
Pasini
D001696:Biomechanical Phenomena; D003187:Compliance; D003198:Computer Simulation; D008962:Models, Theoretical; D018515:Plant Leaves / Q000033:anatomy & histology / Q000502:physiology*; D012250:Rheum / Q000033:anatomy & histology* / Q000502:physiology*; D013314:Stress, Mechanical; D054159:Torsion, Mechanical
Flexural stiffness; rhubarb; torsional stiffness; twist-to-bend ratio