Analysis of the Longitudinal-Bending-Torsional Coupled Vibration Mechanism of the Drilling of a Roof Bolter for Mine Support System

Table 1

Parameters of drill string.

Parameters	1^st unit	2^nd unit	3^rd unit	4^th unit	5^th unit	6^th unit	7^th unit	8^th unit
Elasticity modulus (GPa)	210	210	210	210	210	210	210	210
Density (kg/m^−3)	7850	7850	7850	7850	7850	7850	7850	7850
Length (m)	0.086	0.086	0.086	0.086	0.086	0.086	0.086	0.035
Outer diameter (m)	0.038	0.038	0.038	0.038	0.038	0.038	0.038	0.032
Inner diameter (m)	0.034	0.034	0.034	0.034	0.034	0.034	0.034	0.006