# Simulation and Experimental Study on the Shrub-Cutting Performance of Quasi-Planetary Cutter
## 1 Introduction  
The scope of forest tending operations includes the cutting of forest shrubs. Clearing forest shrubs improves the growth environment of forest trees and facilitates their development and reproduction. A shrub is a woody plant without a distinct trunk, and its physical properties are similar to those of ordinary woody plants [1]. Shrubs exhibit notable structural differences in axial and radial directions, leading to significant variations in their physical and mechanical properties depending on orientation--a characteristic known as anisotropy [2]. This property is commonly applied in finite-element simulations to model the deformation behaviour of shrub materials under external forces using a linear elastic orthotropic material constitutive model [3]. When employing the constitutive model of linear elastic orthotropic materials, most scholars list the relevant parameters but do not specify how these parameters are obtained [4, 5]. The orthotropic anisotropy parameters of different shrubs vary considerably, necessitating experimental measurement and calculation of mechanical and physical properties such as density, elastic modulus, and Poisson's ratio. Mechanical property testing of wood primarily involves a universal mechanical testing machine and material mechanics methods, in which wood samples undergo compression and shear tests to determinemechanical and physical parameters [6]. Based on a specific form of orthogonal anisotropy--transverse anisotropy--this study conducted axial and radial compression tests on shrubs. Through analysis and calculation, the mechanical parameters of the homotopic and heterotropic surfaces of shrubs were obtained. By incorporating shrub density, the material constitutive properties of shrubs were determined. Shrubs are hard-stemmed plants with a high degree of lignification, significant hardness, and other characteristics that make them difficult to cut. This challenge is particularly evident in their high power consumption and low cutting efficiency [7]. The most common cutting methods for hard-stemmed plants are reciprocating cutting and rotary cutting. Reciprocating cutting operates through the linear movement of the blade, creating a shearing effect to achieve the cutting action. This method offers high cutting precision, flexible operation, and other advantages. To reduce the cutting force and ensure the quality of the cut section in the stubble trimming of _Caragana korshinskii_ (C.K. ), [PERSON] et al. [8] proposed a concentric curved-edge sliding cutter. They developed a shear test bench to analyse its cutting characteristics, established a regression model, and determined the optimal shearing parameter combination. However, reciprocating cutting has a limited range, is unsuitable for rapid operation over large areas, and is prone to blade damage from impacts. Rotary cutting, by contrast, achieves cutting through the high-speed rotation of the blade, using centrifugal force and blade sharpness to slice or strike the vegetation. This method is characterised by high cutting speed, efficiency, and strong adaptability. [PERSON] et al. [9] constructed a circular saw blade cutting test bench for C.K., designing both single-factor and orthogonal tests to assess the effects of sawing speed, feed speed, number of teeth, and cutting angle. They determined the optimal sawing parameters for C.K. : a sawing speed of 45.24 m/s, a feed speed of 0.34 m/s, a cutting angle of 10\({}^{\circ}\), and 100 teeth. These optimised parameters reduced the cutting power consumption of C.K. sawing and improved the cutting quality. Given its high efficiency and strong adaptability, rotary cutting has become the predominant method for shrub cutting. Based on the cutting characteristics of shrubs and the configuration of planetary gears [10], this study designed a quasi-planetary shrub-cutting tool. The three blades are arranged in an equilateral triangle, and the entire tool rotates via the spindle to cut shrubs.