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

Table 5

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

Compressed column height, H’ (mm)	Filled ball number, n	Filling ratio, ϕ	Porosity, λ	Energy reflectivity, γ
90.85	580	0.575	0.425	0.281
107.44	710	0.595	0.405	0.271
126.17	816	0.582	0.418	0.251
142.93	923	0.581	0.419	0.226
163.71	1065	0.585	0.415	0.215