Construction and parameter calibration of potato double‐layer flexible bonding model based on discrete‐element method

Abstract The current discrete‐element simulation models for potatoes are multisphere polymer models derived from the Hertz–Mindlin (no slip) contact model in the discrete‐element simulation software (EDEM). These models oversimplify by considering potato peel and flesh as sharing identical mechanical properties within the structure. This oversimplification impedes a thorough investigation of the characteristics and mechanisms underlying potato peel‐breaking damage during mechanized harvesting, making in‐depth exploration challenging through simulation experiments. Consequently, this study conducted laboratory tests to determine the water content of potato peel and flesh, as well as the friction coefficients and collision recovery coefficients for various material pairs: flesh–steel, peel–steel, peel–peel, peel–flesh, and flesh–flesh. Subsequently, based on these findings, a double‐layer flexible bonding model for potato samples and whole stems under specific water content conditions was developed using EDEM software. The bonding parameters of the double‐layer flexible model for potato samples were refined through virtual shear calibration tests, leading to the identification of the optimal parameter combination: Flesh particle–flesh particle normal stiffness(tangential stiffness) per unit area X 1 = 4.39 × 10 8 N/m 3 , peel particle–flesh particle normal stiffness(shear stiffness) per unit area X 3 = 1.81 × 10 9 N/m 3 , peel particle–peel particle shear stiffness per unit area X 6 = 1.99 × 10 9 N/m 3 , peel particle–peel particle critical normal stress X 7 = 2.06 × 10 9 Pa. To validate the accuracy of the bonding parameters, shear and compression validation tests were conducted on entire potato stems. Comparison of the validation results from laboratory tests and simulation tests revealed an average relative error of e = 3.25%, signifying the feasibility of the constructed double‐layer flexible bond model for potatoes. This model meets the requirements for studying the characteristics and mechanisms of peel‐breaking damage in potatoes. Practical Applications The paper introduces a novel double‐layer flexible bonding model for potatoes using the discrete‐element method (DEM), which accurately simulates the mechanical properties and damage characteristics of potato peels and flesh. This research has significant practical applications in agricultural machinery design, improving the efficiency and reducing the damage during mechanical harvesting. By providing a more realistic simulation of potato behavior under mechanical stress, it can guide the development of gentler handling equipment, reduce waste, and enhance the quality of harvested potatoes. This contributes to optimizing the post‐harvest process, ensuring better storage, and extending the marketable life of potatoes.