An innovative approach to plastic mulch film modeling based on the discrete element method

Numerical simulation of the mechanical properties of the plastic mulch film is conducive to the research of its pick-up mechanism and the development of the recycling equipment, however, it remains challenging due to its small thickness and large elongation. This study proposed an innovative discrete element model construction method for the plastic mulch film based on triangular elements. A composite model containing a base and bound layer was constructed to reflect the mechanical properties at different tensile stages. Using polypropylene (PE) films with a thickness of 0.02 mm as samples, the discrete element parameters of the bound layer, base layer, and interlayer were calibrated based on the uniaxial tensile test with tensile strength and elongation as the response values. The accuracy and structural influence of the discrete element model of plastic mulch films were assessed by tensile and puncture tests. The results show that the errors of tensile strength, elongation ratio, and yield strength were 2.36%, 0.19%, and 4.59%, respectively, which proved that the model could accurately reflect the mechanical property of plastic mulch films and the addition of the bound layer could improve the performance of the model in different tensile stages. The errors of the double-sided puncture force were 8.37% and 7.48%, indicating that the double-layer composite model was accurate and the difference between the double-sided properties was slight. The method of constructing the plastic mulch film model based on the discrete element method (DEM) proposed in this study was feasible, and the DEM model of the plastic mulch film had a small computational cost, which provides a new perspective for the numerical simulation of flexible film-like materials.