离散元法在农业工程研究中的应用现状和展望

现代农业装备数字化设计是农业工程领域的主要研究方向之一，农业机械与各类农业物料的接触作用及其对农业机械设计工作的影响是现代农业装备数字化设计重要内容和难点。离散元法是一种基于不连续性假设的计算机数值模拟方法。研究表明，离散元法可以用于仿真分析农业散体物料与机械装备间的相互作用关系，为现代农业装备数字化设计提供了新手段，在农业工程领域具有良好的应用前景。本文对离散元法的基本概念、发展历程及常见程序软件进行了概述，归纳分析了离散元法在模拟农业土壤与农业物料接触时的模型确定及其参数标定方法，重点阐述了各作业环节典型农业机械的离散元法应用现状和发展动态。对基于离散元的数值模拟仿真及其工业化应用推广所面临的主要问题进行了分析和总结，指出通用参数标定方法缺失和模型过度简化是离散元法进一步发展的制约因素，加强接触模型和参数标定的基础研究工作，推动专业、通用的软件平台开发，提高计算机计算和存储能力及改进离散元算法结构，从而提升模型计算效率将是今后的研究方向和工作重点。

Critical Review of Applications of Discrete Element Method in Agricultural Engineering

Digital design of modern agricultural equipment, which is one of the pillars of digital agriculture, is important for achieving a fully mechanized crop production system. Understanding how agricultural equipment interacts with agricultural materials is a prerequisite for designing superior agricultural equipment. Discrete element method (DEM) is a discontinuum-based numerical analysis and simulation method. Recent studies have shown that DEM is a promising method of addressing engineering problems in granular and discontinuous agricultural materials. The concept, development stages, and common software packages of the DEM were introduced. The determination of DEM contact models used in modeling agricultural soil and agricultural materials, including seed, biomass, feed, fertilizer, fruit and vegetables, were summarized and their parameter calibration processes were highlighted. It provided a state-of-the-art review of various DEM applications to improve crop farming systems such as soil tillage, seeding and planting, fertilizing and harvesting. The challenges faced by modeling and design engineers using DEM in modern agricultural equipment research and development were discussed and possibilities for improvements were proposed. The limiting factors of using DEM for wider and broader applications were computational intensity and the lack of an effective parameter determination method. Further fundamental studies on contact model and parameter calibration as well as the development of standardized simulation packages and methods needed to be prioritized. With advances in computing power and numerical algorithms for efficient computation, the DEM would emerge from the development stage and became a robust and cost-effective tool of equipment and process design and optimization in the agri-food industry.