Simulation analysis and experiments of leaf stripping process for whole-stalk sugarcane harvesters

The operation quality of the whole-stalk sugarcane harvester stripping mechanism has an important impact on the residual sugarcane leaves after harvest. Reasonable operating parameters can effectively improve the stripping quality of the stripping mechanism.A finite element model was established in this study to simulate the sugarcane leaf stripping process to analyze the stress and force changes of stalk and leaf stripping elements during this process. In order to obtain the optimal operating parameters, the influence of the main operating parameters of the leaf stripping device on the leaf stripping performance was analyzed, especially on the interaction process between the stalk and the leaf stripping elements in the process of leaf striping, as well as the stress and force distribution of the stalk and the leaf stripping elements in leaf stripping process., Single factor simulation experiments were conducted based on the finite element model. In addition, the effects of rotation speed of feeding roller, rotation speed of leaf stripping roller, overlapping length of stalk and leaf stripping element on the maximal stress of stalk and leaf stripping element were evaluated. The results showed that with the increase of rotation speed of feeding roller, the maximal stress of stalk decreased and then increased, increasing continuously with the increase of rotation speed of leaf stripping roller and overlapping length of stalk and leaf stripping elements. A sugarcane leaf stripping test device was established based on the simulation analysis. Six rows leaf stripping elements made with polyurethane material (with a length of 100 mm, a width of 30 mm and a thickness of 10 mm) were mounted evenly on the roller shaft. Box Behnken design and response surface methodology(RSM) were used to analyze the effects of rotation speeds of feeding roller and leaf stripping roller, overlapping length of stalk and leaf stripping elements and feeding number on non-cleaning rate of sugarcane leaves. Experimental data were analyzed by using SAS 9.3. Through nonlinear optimization, the optimal operating parameters were determined as rotation speed of feeding roller of 250 r/min, rotation speed of leaf stripping roller of 540 r/min, overlapping length of stalk and leaf stripping elements of 13.9 mm and feeding number of sugarcane of 1.68. Under these conditions, the predicted value of non-cleaning rate of sugarcane leaves was 2.2%. The results of verification experiments showed that the non-cleaning rates of of sugarcane leaves were 2.0% and 3.1% respectively when the feeding number of sugarcane were 1 and 2 respectively. The high-speed photography experiment results suggested that the leaf sheath stripping process mainly included separation of the upper part of leaf sheath from the stalk, separation of the lower part of leaf sheath from the stalk, and sliding of leaf sheath along the stalk. The conveying speed of sugarcane fluctuated in the range of 2.3-2.9 m/s at the rotation speed of feeding roller of 250 r/min, rotation speed of leaf stripping roller of 540 r/min and with the overlapping length of 14 mm. Under the high rotation speed of the roller, the conveying speed of the stalk fluctuates violently, which leads to the stalk fracture. The study results can provide reference for improving the leaf stripping performance and adaptability of whole-stalk sugarcane harvester. © 2020, Editorial Department of the Transactions of the Chinese Society of Agricultural Engineering. All right reserved.