*Article* **Simulation and Experiment of Compression Molding Behavior of Substate Block Suitable for Mechanical Transplanting Based on Discrete Element Method (DEM)**

**Jingjing Fu 1, Zhichao Cui 1, Yongsheng Chen 1, Chunsong Guan 1, Mingjiang Chen 1,\* and Biao Ma 2,\***


**Abstract:** The compression molding performance of a substrate block has a significant effect on the quality and stability of mechanical transplanting. The physical experiment and DEM simulation were combined to evaluate the compression molding behavior of substrate block in this study. A calibration procedure of DEM parameters of peat particles was proposed at first. Then, the above parameters were brought into the contact model of the compression system–particles, and the effect of the loading speed on the compression behavior of the peat substrate block was investigated. The compressive force–displacement curves of the simulated and measured tests were all contained in the initial linear stage and non-linear stiffing stage. The particle number of central sections was higher than side section, and the variable coefficient was greater at higher loading speed. The substrate blocks all expanded after demolding. The higher the loading speed, the greater the expansion in the height's direction, and the easier it was for cracks to be generated near the bottom. This study will provide a reference for the design of substrate block forming machines.

**Keywords:** substrate block; compression molding; DEM; parameter calibration; seedling transplanting
