The elastoplastic flexural behaviour of corn stalks

With the purpose of quantifying and understanding the elastoplastic flexural behaviour of corn stalks, this work presents a novel three-point cyclic bending test for characterizing the biomechanical properties of controlled corn stalks. The tests have resulted the first-of-its-kind biomechanical database of corn stalks subjected in repeated bending. Moreover, an experiment-informed bending stiffness model is introduced to calculate the elastic bending angle limits, elastoplastic bending angle limits, elastic bending stiffnesses (or effective bending stiffness), and plastic ratios as well as their variabilities in the tested samples, revealing unique insights into the corn stalk flexural properties. The overall elastic bending limit decreased (from 3.4 to 1.7°) with increasing stalk size, whilst the effective bending stiffness increased (from 7.0 to 43 N m rad⁻¹ in median value). The elastoplastic behaviour of the stalks is more consistent and independent of stalk size where in median value the elastoplastic bending limit ranged from 6.9 to 8.8° and the ratio of elastoplastic stiffness to elastic stiffness ranged from 0.40 to 0.42. Furthermore, statistical analysis of the samples and empirical results have presented insightful expressions to relate the stalk scales to responses, or distributions in properties for a population of corn stalks. The database and statistical analysis and regression expression from this work also allow for parameterizing existing numerical models for simulations of corn stalks and development of more sophisticated deformation models.