Design and experiment of moso bamboo delimbing blade based on EDEM-ANSYS coupled simulation

Moso bamboo is a species of giant timber to serve as a natural composite material worldwide. Conventional blades cannot fully meet the low efficiency and cutting performance of manual delimbing during harvesting. In this study, a biomimetic profiling blade was inspired by the mandibular contour of the Acanthomyrmex glabfemoralis ant. Soldier ants of this species were selected as a biological prototype. The outstanding cutting and mechanical strength of their mandibles were optimized after long-term natural evolution. The morphologies and geometric configuration of the serrated mandible teeth were systematically characterized by scanning electron microscopy with digital image processing. Reverse engineering techniques were employed to accurately extract the contour curve of the mandible serrations after observations. A profile model of the cutting edge was established to derive the mathematical equation of the biomimetic edge. A biomimetic delimbing blade was formed to serve as the geometric structure. Compared with conventional flat-edge blades, a non-uniform curvature profile of the blade was integrated to enhance stress distribution and cutting stability during operation. A bidirectional dynamic framework was constructed to systematically evaluate the cutting performance of the biomimetic blade using the coupled EDEM and ANSYS simulation. A discrete element model of bamboo branches was first developed in the EDEM platform, in which the internal reinforced fiber structure of bamboo was represented by the Hertz–Mindlin with Bonding contact model. Bonded particles were used to simulate the mechanical and fracture behavior of the fibrous vascular bundles. A finite element model of the blade was constructed with the optimal material properties and boundary conditions in ANSYS software. A bidirectional coupling interface was achieved for the real-time data exchange between the blade and the bamboo branch. Synchronous analysis was also performed on the contact forces, bond breakage evolution, and structural stress response during delimbing. A three-factor, three-level orthogonal experiment was implemented to investigate the effects of the edge of the blade, blade thickness, and feeding speed on two key performance indicators: the bond breakage number and the maximum equivalent stress. Response surface analysis revealed that there were significant differences in these influencing factors. In the number of bond breakages, the blade edge was the most significant factor, followed by blade thickness, while the feeding speed had a relatively smaller effect. The optimal combination of parameters was obtained after multi-objective optimization: blade thickness of 4 mm, blade edge of 26°, and feeding speed of 1.6 m/s. The better performance of the biomimetic blade was achieved under these optimal conditions. The maximum equivalent stress and the number of bond breakages were reduced by 16.33% and 6.66%, respectively, compared with the conventional flat blade. Bench experiments were conducted to further validate the reliability of the simulation. Both the conventional flat blade and the biomimetic blade were used to cut bamboo branches under identical operating conditions. Cutting quality was evaluated to measure the impurity rate on the cut surface. The average impurity rate was 4.06% for the flat blade, whereas the biomimetic blade achieved a lower error of 2.36%, corresponding to a reduction of 1.7 percentage points. Overall, the delimbing blade was optimized to integrate the biological inspiration, reverse engineering, and coupled DEM–FEM simulation. The finding can provide theoretical insights into the cutting mechanism of fibrous biological materials. Technical support can also offer to optimize the structure and performance of delimbing tools during moso bamboo harvesting.