Table 3.

AXIAL loading: Slope values in N/mm, characterizing the effective passive stiffness of ring modules, were calculated based on linear trends between zero and maximum displacement points

Passive Stiffness Values Average ± St.Deviation (N/mm)		AXIAL loading
		negative direction	positive direction	both directions	overall
TWIN RING module	± 3 mm	67.2 ± 0.2	69.1 ± 0.2	68.2 ± 1.1	71.4 ± 3.0
	± 5 mm	70.2 ± 0.2	75.1 ± 0.1	72.7 ± 2.6
	± 7 mm	75.3 ± 0.2	71.2 ± 0.2	73.2 ± 2.1
SINGLE RING module	± 3 mm	92.3 ± 0.2	92.2 ± 0.4	92.2 ± 0.3	94.4 ± 2.9
	± 5 mm	98.0 ± 0.2	95.1 ± 0.2	96.6 ± 1.5
	± 7 mm	98.0 ± 0.2	91.1 ± 0.3	94.5 ± 3.6