## Materials and Methods
### FE Model under Driven Modes  
All numerical simulation experiments were conducted using finite element analysis software ANSYS 2021 R1/Transient Structural. In order to balance accuracy and simulation experiment duration, the unit size was set to 7 mm, ensuring that the number of grid elements for cell walls AD and BD was 5. The number of grid layers for the loading board was set to 3. The contact form between the roller's DVWH outer profile and the loading plate was set as surface contact, with a friction coefficient of 0.35, and the walls of each cell were set as self-contact. The rotation constraint was applied to the roller DVWH structure, and the rotation axis was set as the center of the roller-shaped circle. The compression between the log and the feeding roller was simulated by applying pressure to the rigid loading plate. The material of the loading plate was Q345B steel, with a density of 7850 kg/m\({}^{3}\), [PERSON]'s modulus of 206 GPa, and Poisson's ratio of 0.3. The roller-shaped DVWH's base material was polyurethane powder, with a 950 kg/m\({}^{3}\) density, [PERSON]'s modulus of 1100 MPa, and Poisson's ratio of 0.41. In the preliminary research of our research group, grid independence testing was conducted on the impact experiment of the roller DVWH structure [44]. When the number of nodes in the finite element model grid exceeded 39,712, its peak stress value converged. In the numerical simulation experiment of the driven mode of the roller DVWH structure used in this work, the number of mesh nodes in the finite element model reached 59,636, which can meet the accuracy requirements. As shown in Figure 2a, the log is clamped by a pair of rollers. After being flattened horizontally, the rollers begin to feed, accelerate to the set speed, rotate at a constant speed for a specific time, and finally slow down to a stop. The chainsaw cuts the protruding part of the log. According to the workflow of the forest joint harvester, the simulation experiment process was divided into two steps. Firstly, the rigid loading plate was squeezed in the Y-direction at a speed of 0.01 m/s until the honeycomb reached the specified compression rate. During this period, the \(Z\)-axis displacement of the loading plate was limited, with boundary conditions of \(u(Z=0)=0\), \(F_{x}=0\), and \(u(\mathrm{Y}=\mathrm{L})=d\). The second step was to maintain the Y-axis displacement of the loading plate. The roller-shaped DVWH rotated at a specified speed around the \(Z\)-axis, driving the loading plate to move in the X-direction. The boundary conditions of the loading plate were \(u(Z=0)=0\), \(F_{x}=0\), and \(u(\mathrm{Y}=\mathrm{L})=d\), and the boundary conditions of the roller were \(u(Z=0)=0\) and \(F_{x}=0\). The out-of-plane displacement of the loading plate and honeycomb was limited throughout the entire process and the X-direction degrees of freedom of the loading plate were released. The value of \(d\) is given according to Formula (6) and Table 2, and the speed is given in Table 2.  
Compression rate \(\varepsilon\) and speed \(v\) are essential parameters for simulating the roller feeding process. This article investigates their effects on the rotation process of a DVWH roller with a certain amount of preload. Compression ratio \(\varepsilon\) is defined as:  
\[\varepsilon=\frac{d}{R}, \tag{6}\]  
where \(R\) is the radius of the DVWH roller. In order to obtain the influence trend of compression rate and rotational speed, multiple sets of experiments need to be conducted. Due to the fact that the feeding roller is generally in the elastic deformation range during operation, the compression rate \(\varepsilon\) was taken in the range of 10-15%. The speed of the feed roller of the combined logging machine during the uniform rotation stage is 320 mm/s [2]. Because the logging machine usually cuts the fallen wood into a fixed length during operation, the linear speed was used to represent the rotational speed.