MECHANICS OF THE MAIZE LEAF - A COMPOSITE BEAM MODEL OF THE MIDRIB

The midrib is the major stiffening element of maize leaves. Its anatom ical study reveals a complex cross-sectional shape and a composite con stitutive material. A mechanical model is proposed, based on composite beam theory, to account for the bending mechanical behaviour of a bea m element with an heterogeneous cross-section of any transverse shape. The inputs into the model are the outlines of the various material su rfaces within the cross-section, and their corresponding Young's modul i. The predicted outputs are tested against experimental data from an in vivo flexural test. The model prediction gives a good first order a pproximation of the experimental data. The maize midrib can thus be co nsidered as a sandwich beam. The model can also be applied more genera lly to any plant axis, once given the outlines and the rheologies of i ts constitutive material.