Bonding contact model.

A coal model containing gangue was established by discrete elements to study the forces occurring when a shearer cuts coal, and a rigid-flexible coupled shearer section model was established in RecurDyn; the drum cutting process was simulated through bidirectional coupling. The dynamic distribution of the force chain was obtained when cutter teeth cut the coal rock. During the cutting process, the coal rock failure is caused by normal and tangential forces, with the latter having a major role. The ratio of the average tangential force to normal force was 1.34~1.79. When the rock is in the middle of the coal seam, the force (including normal and tangential forces) on the rock is the highest. Moreover, the force on the rock-coal interface is greater than that on the coal-rock interface. The results show that the force on the coal decreases with the increases in rotation speed. In contrast, the number of broken bonds increases. Further, the number of broken bonds and the force of coal increased nonlinearly with traction speed. Finally, the increase of tooth mounting angle decreased the force on the coal rock and the number of broken bonds, followed by an increase. As such, this study provides a reference for further theoretical research on forces in coal cutting.</div

Relationship between the traction speed and force on coal rock and the number of broken bonds.

Relationship between the traction speed and force on coal rock and the number of broken bonds.</p

Particle contact model parameters.

A coal model containing gangue was established by discrete elements to study the forces occurring when a shearer cuts coal, and a rigid-flexible coupled shearer section model was established in RecurDyn; the drum cutting process was simulated through bidirectional coupling. The dynamic distribution of the force chain was obtained when cutter teeth cut the coal rock. During the cutting process, the coal rock failure is caused by normal and tangential forces, with the latter having a major role. The ratio of the average tangential force to normal force was 1.34~1.79. When the rock is in the middle of the coal seam, the force (including normal and tangential forces) on the rock is the highest. Moreover, the force on the rock-coal interface is greater than that on the coal-rock interface. The results show that the force on the coal decreases with the increases in rotation speed. In contrast, the number of broken bonds increases. Further, the number of broken bonds and the force of coal increased nonlinearly with traction speed. Finally, the increase of tooth mounting angle decreased the force on the coal rock and the number of broken bonds, followed by an increase. As such, this study provides a reference for further theoretical research on forces in coal cutting.</div

Drum and the statistical areas.

A coal model containing gangue was established by discrete elements to study the forces occurring when a shearer cuts coal, and a rigid-flexible coupled shearer section model was established in RecurDyn; the drum cutting process was simulated through bidirectional coupling. The dynamic distribution of the force chain was obtained when cutter teeth cut the coal rock. During the cutting process, the coal rock failure is caused by normal and tangential forces, with the latter having a major role. The ratio of the average tangential force to normal force was 1.34~1.79. When the rock is in the middle of the coal seam, the force (including normal and tangential forces) on the rock is the highest. Moreover, the force on the rock-coal interface is greater than that on the coal-rock interface. The results show that the force on the coal decreases with the increases in rotation speed. In contrast, the number of broken bonds increases. Further, the number of broken bonds and the force of coal increased nonlinearly with traction speed. Finally, the increase of tooth mounting angle decreased the force on the coal rock and the number of broken bonds, followed by an increase. As such, this study provides a reference for further theoretical research on forces in coal cutting.</div

Relationship between the rotational speed and force on coal rock and the number of broken bonds.

Relationship between the rotational speed and force on coal rock and the number of broken bonds.</p

Arrangement of drum picks and cutting section model.

(a) drum pick arrangement. (b) cutting section model.</p

Bidirectional coupling simulation.

(a) discrete element simulation. (b) RecurDyn simulation.</p

The flexible pick element.

A coal model containing gangue was established by discrete elements to study the forces occurring when a shearer cuts coal, and a rigid-flexible coupled shearer section model was established in RecurDyn; the drum cutting process was simulated through bidirectional coupling. The dynamic distribution of the force chain was obtained when cutter teeth cut the coal rock. During the cutting process, the coal rock failure is caused by normal and tangential forces, with the latter having a major role. The ratio of the average tangential force to normal force was 1.34~1.79. When the rock is in the middle of the coal seam, the force (including normal and tangential forces) on the rock is the highest. Moreover, the force on the rock-coal interface is greater than that on the coal-rock interface. The results show that the force on the coal decreases with the increases in rotation speed. In contrast, the number of broken bonds increases. Further, the number of broken bonds and the force of coal increased nonlinearly with traction speed. Finally, the increase of tooth mounting angle decreased the force on the coal rock and the number of broken bonds, followed by an increase. As such, this study provides a reference for further theoretical research on forces in coal cutting.</div

The relationship between the tooth mounting angle and the force acting on the coal rock and the number of broken bonds.

The relationship between the tooth mounting angle and the force acting on the coal rock and the number of broken bonds.</p

The relationship between the normal force, tangential force, and the number of broken bonds.

The relationship between the normal force, tangential force, and the number of broken bonds.</p