Structure Optimization of Rib Drill Pipe Based on Gas-Solid Coupling and Orthogonal Experiment

Table 3

Material parameters and contact parameters.

Material parameters	Coal	Steel
Density	1400 kg/m^3	7800 kg/m^3
Poisson’s ratio	0.3	0.3
Shear modulus	2e + 02 MPa	1e + 04 MPa
Contact parameters	Coal-coal	Coal slag-drill pipe
Coefficient of restitution	0.5	0.5
Coefficient of static friction	0.6	0.4
Coefficient of rolling friction	0.05	0.05