Multi-scale decoding of cavity-forming stress dynamic: insights from experimental and simulation data

As a critical component in the transplanting process, the soil disturbance caused by the transplanter opener during cavity formation directly affects seedling establishment quality. Current design methodologies, predominantly relying on macroscopic force measurements, provide limited insight into the underlying soil failure mechanisms. Indoor soil-bin experiments were conducted using the Tekscan high-resolution pressure mapping system to capture the full-field dynamic stress distribution during cavity formation. Combined with a developed Discrete Element Method (DEM) simulation model (RMSE = 7.77 kPa, R² = 0.9091), the stress variation trend was accurately reproduced, enabling multi-scale analysis of the soil disturbance mechanism. The results showed that the peak normal stress and stress concentration occurred just before the opener reached its lowest position, with a maximum cavity-forming normal stress of approximately 20 kPa. Quantitative analysis revealed that soil moisture content had a significant non-linear relationship with the maximum disturbance area, which first increased and then decreased with increasing moisture ( R ² = 0.98). Soil penetration resistance showed a positively accelerating increase in disturbance area ( R ² = 0.98). In contrast, forward speed had a relatively weak influence, showing only a slow increasing trend ( R ² = 0.96). This study systematically elucidates the evolution of dynamic stress during cavity formation and the quantitative influence of multiple parameters. The proposed "Tekscan-DEM" integrated approach provides a new pathway for studying agricultural machinery-soil interactions. The findings offer both theoretical foundations and methodological support for developing next-generation, low-disturbance openers.