Cutting is a fundamental machining method extensively utilized across various fields, including mechanical engineering, agriculture, forestry, biomedical instrumentation, mineral exploration, and extraterrestrial missions. However, during cutting operations, tools are exposed to high temperatures and friction, which result in diminished cutting efficiency, reduced tool life, and compromised workpiece quality. Advances in bionics are gradually mitigating these challenges. Bionic design provides rich, reliable, and efficient prototypes that enhance tool performance while promoting environmentally friendly, harmonious, and sustainable tool development. In the bionic optimization of cutting tools, the selection of appropriate bionic prototypes and models is crucial. However, the complexity and ambiguity inherent in bionic prototype functions impede the development and widespread adoption of bionic tools. This paper initially focuses on the classification of bionic tools, subsequently proposing five categories of bio-inspired design elements and topological models from the perspective of bioinspired cutting tools. The second discusses the applications, advantages, and cutting performance of five types of bionic tools, with an emphasis on both the biomimetic optimization of the tool body and non-tool bodies. These tools are designed by emulating the diverse biological characteristics exhibited by various organisms. Additionally, the underlying mechanisms of the five categories of bionic tools, as well as the corresponding optimization strategies, are explored. Finally, this paper summarizes research on bionic tools and analyzes the current opportunities and challenges they face. In summary, compared to traditional tools, bionic tools demonstrate superior performance in energy efficiency, friction reduction, wear resistance, lubrication, extended service life, and multifunctionality. This offers valuable insights for researchers involved in the design and development of cutting tools.

Artificial fractures on the tunnel face can promote tunnel boring machine (TBM) performance in the intact rock mass with high rock strength. High-pressure water jet (HPWJ) is a feasible choice to pre-cut the kerfs on the tunnel face to assist in TBM tunnelling. To study the effects of different layouts of the TBM cutter and HPWJ on the cutting performance and the corresponding rock breakage mechanism, a series of full-scale linear rock cutting tests were conducted. The analysis included the TBM cutter force, cutter vibration, rock muck and rock-breaking specific energy. According to the results, two HPWJ-assisted cutting layouts are recommended. One is arranging the HPWJ nozzle ahead of the cutter, making the cutter cut along the kerf. The rock damage zone after the cutter penetration was rather limited since the kerf beneath the cutter prevented the formation of the pressurized crushed zone and the generation of the lateral cracks that occurred in the intact rock. The lowest cutter force and vibration were obtained with the shallow kerf depth compared with the other layouts. Creating kerfs with a depth slightly lower than the cutter penetration is suggested to vastly save energy. Another recommended layout is arranging the nozzles between all the cutter trajectories, making the cutter cut along the middle line of two kerfs. The breakage mechanism turned to the interaction between the cutter and adjacent kerfs, macro-cracks generated from the cutter tip could propagate to the bottom of kerfs on both sides. The cutter force and the magnitude of oscillations decreased with the increasing kerf depth. The largest rock-breaking volume and lowest specific energy were obtained among all the tests. The suggested kerf depth is about twice the cutter penetration, above which the specific energy would not significantly decrease. The study is helpful to the cutterhead design of the TBM assisted with HPWJ and the promotion of TBM performance. Linear cutting tests using the HPWJ and full scale TBM cutter were successively performed with various layouts.The analysis of cutter performance comprises force, induced vibration, specific energy and mucks characteristics, validating the feasibility of the assistance of HPWJ.Arranging HPWJ nozzles on and between the cutter trajectories were recommended to drastically reduce the cutter force and specific energy, respectively