# Alfafa Stalk Crushing Simulation Test and Parameter Optimization Method
## 2 Materials and Methods
### Methods  
This study utilized the finite element method to analyze the frame and the discrete element method to investigate the material crushing process. The former aimed to identify the first six modes and frequencies of the rack to assess the possibility of resonance and to determine if optimization was necessary. The latter focused on examining the crushing process of devices with various structures and selecting the one with a superior performance. This study utilized ABAQUS 2022 software to analyze the first six modes and frequencies of the frame through finite element analysis. ABAQUS is a highly effective engineering simulation software extensively utilized in a range of industries including machinery, electronics, materials, and civil engineering. It offers a wide range of physical models and advanced numerical methods to accurately simulate the behavior and performance of complex systems and components. The results obtained using ABAQUS were compared with the external excitation frequency to assess the possibility of resonance. If the natural frequency of the rack falls within the range of excitation frequency, further optimization of the frame was carried out. This optimization involved modifying the structural size to enhance the stiffness of the frame, thereby increasing its natural frequency and avoiding the excitation frequency range. This study employed the discrete element method to conduct a single-factor crushing simulation test on alfalfa stems. The objective was to investigate the impact of different rotation speeds and tool structures on the crushing of alfalfa stems. Subsequently, orthogonal experiments and range analysis were employed to identify the primary and secondary influencing factors, and to determine the optimal parameter combination. EDEM 2022 software is a simulation software that is suitable for analyzing discrete particles. It is based on particle collision theory and discrete element theory, and it is combined with powerful coupling functions to jointly simulate particles, fluids, and mechanical equipment [6; 7]. This study used EDEM simulation software to conduct discrete element analysis to explore the effects of crushing structure and rotational speed on the stalk crushing effect. In ad  
Figure 2: Five types of forage crushing structures. (**a**) Hammer crushing structure with blade; (**b**) Hammer rod crushing structure; (**c**) Hammer crushing structure without blade; (**d**) Roller crushing structure; (**e**) Hob crushing structure. dition, the type and rotation speed of the crushing tool were considered as influencing factors. The fracture of the bond in EDEM was used as the basis for evaluating the crushing effect [8,9]. In the EDEM software, the bonding model is utilized to bond particles together. When both the tangential force and normal force endured by the bonds exceed the limit value, the bonds will break and the particles will separate from each other, achieving the purpose of breaking [10, 11, 12]. Therefore, this study employed EDEM software to construct a bonding model of alfalfa stems. The alfalfa stems were simulated as fine particles that are held together by bonds. The fracture of these bonds was used to assess the effectiveness of the crushing device in breaking down alfalfa stems [13, 14, 15]. During the construction of the model, a particle diameter of 5 mm was chosen. A total of 1346 small particles were generated within the alfalfa stalk model as the target particles. The XYZ position parameters of these target particles were collected to compile an API. This API was then used to quickly replace and generate the alfalfa stalk model using the target small particles. Additionally, particle bonds were created to achieve the desired shape of the alfalfa stalk model. Contact parameters and bond parameters specific to alfalfa stalks were set accordingly. Previous studies have extensively investigated these parameters, taking into account factors such as the variety of alfalfa stalks and moisture content.