An Experimental Study of Axial Poisson’s Ratio and Axial Young’s Modulus Determination of Potato Stems Using Image Processing

Abstract

Potato stems removal is an important part of mechanized potato harvesting. However, there is still limited research on the physical properties of potato stems, especially the determination of Poisson’s ratio and Young’s modulus. This study determined the Poisson’s ratio and Young’s modulus of the potato main stems at different heights above the ground. Since the Potato stems are viscoelastic cylinders with non-standard circular cross-sections and complex textures, the existing determination methods are difficult to apply. We propose a new method to determine Poisson’s ratio and Young’s modulus by combining image processing in the mechanical compression process. The feasibility of this method was verified by determining the hardness value of 65 Shore ‘A’ nitrile rubber specimens, and the measured Poisson’s ratio and Young’s modulus were close to the relevant literature. This method can be used for the determination of potato stems. Atlantic potatoes are widely grown for their high solids content, resistance to pests and diseases, and good processing quality. Ten Atlantic potato main stems were randomly selected at harvest time. Specimens with a length of 11 ± 1 mm were taken at 0 cm, 10 cm, 20 cm, and 30 cm above the ground from each stem. The average values of the axial Poisson’s ratio were determined as: 0.21, 0.28, 0.30, 0.32, and the axial Young’s modulus as: 15.90 MPa, 12.38 MPa, 11.68 MPa, 11.28 MPa. This study has provided critical basic data for the discrete element model construction of potato stems and numerical simulation of potato haulm killers and potato harvesters, which is beneficial for improving the harvest quality of potato. It also provides new ideas for Poisson’s ratio and Young’s modulus measurement of non-regular cross-sectional cylindrical viscoelastic materials.