Search Results (4)

Aiming at the problem of lacking accurate and reliable contact and bonding parameters in the discrete element simulation of whole cotton stalk harvesting equipment, this study proposed a reverse modeling method for cotton roots combining the Discrete Element Method (DEM) with 3D laser scanning. This method systematically constructed a general discrete element model and completed its parameter calibration. Firstly, cotton root samples were collected and measured to obtain key morphological parameters, providing a basis for selecting representative roots and performing 3D reverse reconstruction. Subsequently, mechanical parameters and contact parameters of the cotton roots were measured and calibrated through mechanical tests and stacking angle tests. Furthermore, based on the Hertz–Mindlin with Bonding contact model, a structured root sample model was established using a layered particle combination strategy. The bonding parameters were then optimized and calibrated through shear and tensile mechanical simulation experiments. Finally, a discrete element model of the root–soil complex was established based on the optimal parameter set. The reliability of the model was validated by comparing the simulation results with physical field tests of root extraction force. The results indicated that in the contact parameter validation test, the relative error between the simulated stacking angle and the measured value was only 0.43%, demonstrating the high accuracy of the model in simulating contact characteristics. In the bonding parameter calibration validation tests, the relative errors between the simulation results and measured values for shear and tensile mechanics were 1.22% and 1.40%, respectively, indicating that the model parameters could accurately simulate shear strength and tensile strength. Finally, in the root extraction force validation test, the relative error between the simulated extraction force and the field-measured value was 3.76%, further confirming the model’s applicability for analyzing the complex interaction mechanisms between roots and soil. The findings of this study can provide key models and parameter support for the digital design, operation process simulation, and performance optimization of whole cotton stalk harvesting equipment. Full article

This study aims to improve the performance of wood–plastic composites (WPCs) composed of cotton stalk powder and residual film particles. Additionally, it aims to promote the efficient utilization of cotton stalk biochar. The composites were prepared using modified cotton stalk biochar and xylem powder as the matrix, maleic anhydride grafted high-density polyethylene (MA-HDPE) as the coupling agent, and polyethylene (PE) residual film particles as the filler. The WPCs were fabricated through melt blending using a twin-screw extruder. Mechanical properties were evaluated using a universal testing machine and texture analyzer, Shore D hardness was measured using a durometer, and microstructure was analyzed using a high-resolution digital optical microscope. A systematic investigation was conducted on the effect of biochar content on material properties. The results indicated that modified biochar significantly enhanced the mechanical and thermal properties of the WPCs. At a biochar content of 80%, the material achieved optimal performance, with a hardness of 57.625 HD, a bending strength of 463.159 MPa, and a tensile strength of 13.288 MPa. Additionally, thermal conductivity and thermal diffusivity decreased to 0.174 W/(m·K) and 0.220 mm²/s, respectively, indicating improved thermal insulation properties. This research provides a novel approach for the high-value utilization of cotton stalks and residual films, offering a potential solution to reduce agricultural waste pollution in Xinjiang and contributing to the development of low-cost and high-performance WPCs with wide-ranging applications. Full article

In order to study the effect of cotton stalk particle size on humification, cotton stalks of different lengths (5 cm, 10 cm, 15 cm) were co-composted with pig manure for 49 days. The results showed that the 10 cm treatment (T2) maintained a high-temperature stage for 8 days, and the total organic carbon decreased by 60.0%. T2 showed the highest cellulose (57.0%) and hemicellulose (77.1%) degradation rate, the lowest lignin accumulation (69.8%), and the highest humus content (34.94 g/kg), which was 88.1% higher than that in the initial stage. FTIR analysis revealed significant changes in functional groups. The aromatic C=C stretching vibration (1650 cm⁻¹) in the T2 treatment group increased by 79.8%, showing a better aromatization degree than the other two groups. Two-dimensional FTIR spectroscopy analysis showed that phenolic and alcohol hydroxyl groups were first involved in humification, followed by polysaccharides, hemicellulose, lignin, and aromatic structures, and the T2 treatment group enhanced this material transformation pathway. Microbial diversity analysis identified seven main phyla, among which T2 showed higher Planctomycetota and Acidobacteria abundance, which was closely related to the degradation of hemicellulose, cellulose, and phenolic compounds. Second, the abundance of characteristic species such as Planifilum fulgidum also showed certain advantages in the T2 treatment group. In summary, the particle size of 10 cm optimized the microbial activity and organic matter transformation and effectively regulated the composting humification process. Full article

The accuracy of the material parameter settings directly affects the reliability of the results of the discrete element method simulation. It is necessary to calibrate the relevant parameters to obtain accurate discrete element simulation results when separating the cotton stalk particles from the residual film after crushing. The repose angle of the chopped cotton stalk particles was used as the response value to calibrate the contact parameters between particles. Physical tests measured the intrinsic particle and contact parameters between the cotton stalk particles and the contact material, which provided data for the simulation tests. According to the biological structure characteristics of cotton stalk, the discrete element method model of cotton stalk particles was constructed by bonding the elements of nonequal-diameter basic particles. Based on the response surface methodology, the stacking test of particles was simulated. The response model between the contact parameters and repose angle was established, and the effect law of the single-factor terms and interaction terms on the repose angle was analyzed. The optimal combination of contact parameters was obtained through the single-objective and multi-variable optimization methods. Finally, the contact parameter combination was verified by a simulation test of the repose angle. The results showed that the average relative error of the repose angle between the simulation test and the physical test was 1.04%, which verified the accuracy of the calibrated contact parameters and the reliability of the simulation test. These parameters provide a basis for the discrete element simulation study of cotton stalk motion in the separation process of cotton stalks and residual film and the subsequent gas–solid coupling simulation research. Full article