Parameters Optimization and Energy Absorption Evaluation of the Steel Ball Friction Energy Absorber

Table 6

Filling ratio and porosity of the ball column with different ball column diameters.

Ball column diameter, Dc (mm)	Filled ball number, n	Compressed column height, H’ (mm)	Filling ratio, ϕ	Porosity, λ	Energy reflectivity, γ
40	1065	163.83	0.585	0.415	0.215
50	1776	161.27	0.634	0.366	0.223
60	2664	170.32	0.626	0.374	0.221
70	3597	174.07	0.607	0.393	0.210
80	4773	176.70	0.608	0.392	0.196