To address the issue of insufficient accuracy in the discrete element simulation model for cotton stalk -residual film mixtures, this paper employs the Hertz-Mindlin model with the JKR contact model to calibrate the contact parameters. First, significant parameters affecting the angle of repose were identified using Plackett-Burman experiments. Subsequently, the optimal parameter range was determined in conjunction with the steepest climb test. A regression model was constructed using Box-Behnken experiments to optimize the parameters, yielding the optimal parameter combination: cotton stalk-residual film rolling friction coefficient of 0.46, residual film-residual film rolling friction coefficient of 0.31, residual film-steel rolling friction coefficient of 0.47, and residual film-residual film JKR surface energy of 0.41 J/m². Simulated pile-up tests were conducted on a mixture of cotton stalks and residual film using these optimal parameter combinations. The results showed that the error between the simulated and measured angle of repose was only 3.06%, validating the reliability of the parameters and providing a basis for research into the interaction characteristics between cotton stalks and residual film during film recovery.

During residual film recovery operations, the mixing of residual film with soil and the absence of accurate interaction parameters significantly hinder the optimization of key machinery components. To tackle this issue, this study develops a discrete element simulation model based on the Hertz–Mindlin with JKR (Johnson-Kendall-Roberts) contact model, using the residual film-soil mixture as the simulated material. The contact parameters were calibrated through a combination of physical experiments and EDEM simulations. Using Design-Expert software, angle of repose tests and Plackett–Burman experiments were carried out to identify the parameters that have a significant influence on the angle of repose. The optimal set of parameters was determined through steepest ascent and Box–Behnken design (BBD) experiments: residual film–soil rolling friction coefficient 0.61, soil–soil rolling friction coefficient 0.60, soil–steel static friction coefficient 0.68, and soil JKR surface energy 0.46 J/m². Validation results indicate relative errors of 4.58% for the angle of repose and 2.58% for the uniaxial compressive strength between simulated and measured values. These outcomes offer a useful reference for optimizing residual film recovery equipment and for modeling soil–residual film composite materials.