Determination of Physical Properties for Discrete Element Model on the Nanji-Type Garlic Cloves

Abstract

© 2022, The Author(s), under exclusive licence to The Korean Society for Agricultural Machinery.Purpose: Agricultural machines, which increase the convenience of agricultural work and enable mass production, are mechanical systems that inevitably interact with organisms based on the characteristics of handling agricultural products. Such crop-mechanical systems often form discrete systems by integrating a large number of agricultural products within the machines. The discrete element method (DEM) is an effective numerical method that is applicable to such discontinuous mechanical systems. However, the information required for a DEM model, such as the shapes, weights, and mechanical properties of crops, is difficult to obtain based on the characteristics of organisms with atypical and large dispersion. Therefore, this study aimed to develop a calibration process that can estimate and verify DEM model parameters for Nanji-type garlic cloves. Methods: The DEM model considers the statistical properties and shape parameters of 500 garlic clove samples and is a cluster model composed of three spherical particles. The Hertz–Mindlin contact model was adopted, and the required parameters for the contact model, including the equivalent Youngs modulus and friction coefficient, were estimated, compared, and verified based on actual compression and shear test results. Results: Simulation results using the calibrated DEM model are in good agreement with the results of compression and shear tests. Further, the statistical properties of crop shape and weight were reflected in the DEM model. Conclusion: The findings will aid the analysis of crop-mechanical systems. In particular, the proposed method has applicability in the design and analysis of planters and harvesters.