# Digging Performance and Stress Characteristic of the Excavator Bucket
## 3 Analysis of ADAMS-EDEM Coupling Simulation Results  
### ADAMS-EDEM Co-Simulation of Mining Process  
Through ADAMS-EDEM co-simulation, the digging resistance, filling rate and energy consumption of the bucket during the excavation process were obtained. As shown in Figure 6, the mining excavation process can be divided into four distinctive stages: 1--the arm and bucket rod are lowered (0-1.4 s), the bucket does not contact the material, and the digging resistance is zero; 2--the bucket starts digging, the bucket is inserted into the pile of material and starts spinning (1.4-4 s). As the digging process progresses, the bucket components are subjected to the intermittent impact of discrete materials, and the bucket digging resistance shows an upward trend. The bucket digging resistance reaches the maximum value at 3.1 s, when the bucket is full of materials, and then the digging resistance decreases continuously; 3--the bucket rod stops moving and the bucket rotates around the bucket rod (4-7 s). During the rotation process, the bucket's angular speed increases from 0 to a fixed value and then starts to rotate at a uniform angular speed. During this process, due to the uneven material gravity and inertial force of the bucket, the mining resistance will inevitably increase under the action of contact impact force during the acceleration process. Then, the bucket gradually fills with materials, and the digging resistance is reduced; 4--the arm and bucket rod are lifted (7-10 s), and the bucket is full of materials. At the time, due to the simultaneous movement of the arm and bucket rod, the digging resistance increases sharply for a short time. After a period of time, the bucket begins to break away from the material pile, and the contact between the bucket and the material pile is reduced. The digging resistance continues to decrease. After the bucket is completely removed from the material pile, the digging resistance of the bucket is the gravity of the materials in the bucket, a few materials fall from the bucket, and the change in digging resistance becomes stable. Figure 5: Bucket constraint settings and meshing. As shown in Figure 7, the digging resistance of different components of the bucket during the excavation process can also be obtained through simulation. The digging resistances of the base plate, side plate, bucket teeth and main blade are adjusted on the EDEM post-processing interface, respectively. As shown in Figure 8, the order of digging resistance reduction at different typical positions of the bucket is as follows: the bucket teeth, main blade, side plate and base plate. The overall digging resistance of the bucket is the sum of the digging resistance of all parts of the bucket. In the initial stage of excavation, the bucket teeth first contact the material, and then the side plate, main blade and base plate contact the material. In 0-4 s, the digging resistance of the bucket teeth accounts for the largest proportion of the total digging resistance of the bucket, while the digging resistance of the other parts of the bucket accounts for a relatively small proportion. While the depth of the bucket inserted into the material pile increases, the digging resistance of each bucket component increases. After the bucket is filled with materials, the digging resistance of each bucket component gradually decreases. When the bucket is completely removed from the material pile, the force of the bucket is the gravity of the material in the bucket. At this time, the resistance of the bucket teeth is almost 0, and the main bearing body is the base plate, so the base plate digging resistance is the greatest. In the early stages of the excavation process, the cutting resistance of the tip of the bucket accounts for a large proportion of the digging resistance. In the later stages of the excavation, the bucket's base plate becomes the main bearing structure because it needs to bear the weight of the loaded materials.