Sugarcane belongs to annual or perennial tropical and subtropical herbs, and the cutting quality of sugarcane stubble has a crucial impact on the growth of cane in the following year. Sugarcane cutting process is a high-speed, transient, and nonlinear dynamic problem. Aiming to explore the cutting mechanism of sugarcane stalks and study the cracking and propagation process of sugarcane cracks based on the fracture mechanics theory, which was to provide a theoretical basis for improving the cutting quality of sugarcane stalk, the mechanical model (bending moment, cutting force, etc.) of the base cutter cutting the stalk was established by analyzing the interaction between the cutter and the stalk, to explore the influencing factors of cutting force; and the high-speed camera technology was adopted to observe the cutting quality of sugarcane stubble cuts with one and multi-times cutting. It was found that the factors affecting the cutting performance were mainly related to the mechanical properties (diameter, density, stalk inclination angle, etc.) of sugarcane stalks and base cutters, the kinematic parameters (cutting frequency, cutting depth) of base cutters, and soil conditions. However, the multi-time base cutting would increase the probability of stubble damage, which was mainly caused by defects and cracks on the stalks after first cutting, and the cracks would extent under its own gravity and external load. Therefore, the internal cracks of the sugarcane stalk were first studied based on the fracture mechanics theory, the crack initiation conditions and the factors affecting the fracture angle were analyzed, and the influence of crack parameters on the stress intensity factor and the expansion amount were explored. The results showed that the change of crack angle and number led to the composite crack, and the I — D composite crack was the main crack type. The stress intensity factor fluctuated greatly with the crack angle changing, and the change of crack direction and extension was due to the angle between the maximum principal stress and the crack propagation surface was affected by the crack angle; when the crack angle was less than or equal to 75°, the crack would continue to expand along the original direction and then bend, however, the crack would expand along the direction perpendicular to the original crack when the crack angle was greater than 75°. During the propagation process of two cracks, the cracks propagated along a 45° direction from the original crack. This was due to the relative slip of the material inside the stem under the influence of the cracks. The shear stress reached its maximum value at the 45° direction. With the increase of number of cracks, the shielding effect between cracks was increased, which would result in the release of the stress in the material at the crack tip, the relative displacement near the crack tip was decreased, and the crack growth was decreased gradually. © 2023 Chinese Society of Agricultural Machinery. All rights reserved.
