Chopped straws can help replenish soil nutrients, improve soil structure, and increase the amount of organic matter contained in soil. The grinding ability of crop straws is influenced by the frictional characteristics of the materials involved in the grinding process. Studying the frictional properties of peanut stem, residual film, and external contact material is essential to understanding the grinding action of peanuts. This study discussed the frictional properties between films and between residual film and external contact materials. A physical test was conducted using a friction coefficient detector. The results showed that the average value of the dynamic sliding friction coefficient (f_k) was 0.34, the average value of the static sliding friction coefficient (f_s) between the film and the 40Cr steel plate (as the external contact material) was 0.38, and the average f_s value between the films and between the residual film and the external contact material was 0.36. Based on the Box-Behnken test, second-order response models were established for the static rolling stability angle (μ_e) and the static sliding friction coefficient (f_s). On the basis of establishing the static rolling stability angle (μ_e) and static sliding friction coefficient (f_s) of the evaluation index, the different friction characteristics between straw and external contact materials were investigated under varying moisture content, external contact materials and particle sizes. The study results can provide a basis for the development of equipment that can be used for peanut straw crushing and membrane separation.

This study constructed a numerical model using the discrete element software EDEM to address the current lack of calibrated contact parameters for peanut seedling membranes and the absence of precise simulation model parameters for mechanized separation. The Hysteretic Spring Contact Model (HSCM) was employed to calibrate the contact parameters of peanut seedling membranes. The angle of repose of peanut seedling membranes was determined through image processing combined with the least squares method. Through central composite design (CCD), a second-order response model linking the contact parameters to the angle of repose was established. Optimization was achieved by using the angle of repose obtained from physical tests as the objective. Secondary simulation tests were conducted with the calibrated parameters, revealing a relative error of 1.37% between the simulated and physical angles of repose. This confirmed the effectiveness of the parameters in calibrating peanut seedling membrane characteristics. The findings offer theoretical and empirical support for discrete element simulations of peanut seedling membrane separation and peanut straw pulverization processes.