Model-Based Experimental Development of Passive Compliant Robot Legs from Fiberglass Composites

Table 3

The estimated and measured elastic modulus of the 4-layer strip composites.

(a)

Type	S-0	S-45	S-90	D-0	D-45	D-90
Estimated (GPa)	19.90	13.03	9.17	11.01	13.03	18.06
Test #1	17.01	14.04	8.90	10.26	12.93	16.50
Error (%)	14.53	7.74	2.94	6.83	0.78	8.63
Test #2	18.67	12.72	8.99	10.99	12.65	18.37
Error (%)	6.19	2.39	1.92	0.15	2.93	1.72
Test #3	19.87	13.16	9.35	11.40	13.97	19.40
Error (%)	0.17	0.99	1.94	3.59	7.15	7.41
Mean	18.52	13.31	9.08	10.88	13.18	18.09
STD	(1.44)	0.67	0.24	0.58	0.70	1.47
Average error (%)	6.95	2.12	0.98	1.15	1.18	0.17

(b)

Type	S′-0	S′-45	S′-90	D′-0	D′-45	D′-90
Estimated (GPa)	25.5	8.78	7.18	23.88	8.78	8.8
Test #1	25.8	8.5	7.32	21.63	8.05	8.66
Error (%)	1.16	3.28	1.90	9.43	8.40	1.56
Test #2	27.16	8.70	6.81	25.53	8.39	9.06
Error (%)	6.5	0.92	5.15	6.91	4.52	3.02
Test #3	25.62	8.87	6.98	25.32	8.92	8.94
Error (%)	0.49	0.93	2.81	6.04	1.58	1.62
Mean	26.19	8.69	7.04	24.16	8.45	8.89
STD	0.84	0.19	0.26	2.19	0.44	0.21
Average error (%)	2.72	1.03	2.00	1.17	3.72	0.98