Table 2.

Material properties and longitudinal pre-stretch for FPAs in seven age groups. Constitutive parameters are provided for the four-fiber FPA model. Second column (n) signifies the number of specimens in each age group used to derive these constitutive parameters (Kamenskiy et al. 2016b).

Age group, years	n	Mean age, years	${\lambda }_z^{\text{in situ}}$	C0, kPa	$C_1^{\mathit{el}}$, kPa	$C_2^{\mathit{el}}$	$C_1^{\mathit{smc}}$, kPa	$C_2^{\mathit{smc}}$	$C_1^{\mathit{col}}$, kPa	$C_2^{\mathit{col}}$	γ,°
11-20	21	16.7	1.53	10.51	20.92	0.22	2.34	1.76	3.32	2.05	60.84
21-30	15	25.0	1.39	16.81	17.35	0.69	7.72	3.68	3.80	3.28	50.17
31-40	26	35.7	1.36	9.96	17.57	0.99	4.74	2.81	2.45	4.10	55.88
41-50	39	47.2	1.27	13.46	14.54	2.41	8.20	7.29	2.31	9.96	46.84
51-60	106	56.1	1.19	10.69	20.77	3.60	11.58	8.38	3.28	13.19	45.62
61-70	83	64.6	1.15	7.83	24.81	5.73	16.82	12.56	5.24	21.76	46.58
71-80	32	76.1	1.10	7.01	37.03	12.81	36.09	15.96	11.65	36.08	45.02