# Experimental and Numerical Studies on the Impact Energy Absorption of Cutting Shear Rings
## 1 Introduction  
As early as the 1960s, the British Railway (BR) proposed the concept of collision mitigation and energy absorption. Subsequently, many scholars carried out relevant research and acquired a lot of achievements [1, 2]. At present, the energy absorption devices extensively used to enhance passive safety are mainly divided into two types: the fracture type and the crushing type. The fracture-type devices refer to the use of friction between the inner and outer tubes when bearing axial impact through the extrusion of the outer tube to make it crack or crack part of the curling deformation to achieve energy absorption, usually in a tube-in-tube structure. The crushing-type devices mainly use the excellent energy absorption effect of metal materials to achieve the purpose of collision mitigation when subjected to axial impact, which is primarily divided into thin-walled tubular, honeycomb, and mesh metal structures [3, 4, 5]. In particular, thin-walled tubular and honeycomb structures are extensively used in various collision energy absorption processes to reduce the impact load and improve the crashworthiness of the structure [6, 7, 8, 9]. The thin-walled structures exhibit excellent performance under dynamic loads and have the advantages of cost-effectiveness and high efficiency, and their energy absorption capacity is closely related to the structure's geometry, material type, and load form [10, 11]. In recent years, [PERSON] [12], [PERSON] [13], [PERSON] [14],[PERSON] [15], et al. researched the energy absorption characteristics and structural optimization of thin-walled structures through different methods, and their related theories and results have been applied to the design of energy absorption devices. Meanwhile, by comparing the response characteristics of thin-walled structures under different impact loads, many scholars analyzed the different failure forms of thin-walled structures [16; 17; 18]. In particular, under the impact of axial load on thin-walled tubular structures, the axial and lateral spaces of energy absorption decrease while the transverse space of energy absorption increases [19; 20]. Therefore, it is necessary for energy absorption devices to reserve lateral deformation space. When the installation space is relatively narrow, the thin-walled structure is difficult to exploit for its superior performance. To improve the performance of energy absorbers with higher absorbed energy, lower peak contact force, and a more stable response process, many scholars have studied the impact resistance of materials [21; 22] and reformed the existing structure [23; 24]. [PERSON] et al. [25] transformed linear metal tubes into S-shaped conical tubes and introduced strengthening and deceleration technologies, which increased the absorption energy by 35% compared with linear tubes. [PERSON] et al. [26] designed dynamic compression and impact properties of a new open-type Ni/Al composite metal foam and compared them with those of pure aluminum foam. The feasibility of Ni/Al composite foams as shock absorbers under explosion and ballistic impact is proven. Meanwhile, [PERSON] et al. [2] found that the energy absorption method with the combined effect of friction, plastic deformation, and tearing between metals is better than the energy absorption method with large plastic deformation of thin-walled metal materials. In other words, the energy absorption method of a cracked energy absorption structure is better than that of a crushed energy absorption structure. [PERSON] et al. [27; 28] proposed a cutting-type energy absorption device based on the principle of chip generation. The energy absorption device must be an irreversible but controllable process in the process of energy absorption. [PERSON] et al. [29] designed a cutting energy-absorbing structure and discussed the effect of structural parameters on the response characteristics using polar difference analysis. They found that the energy absorption was strongly sensitive to the cutting depth and width.