Dynamic Behavior and Fatigue Damage Evolution of Sandstone under Uniaxial Cyclic Loading

Table 3

Strain damage model parameters of sandstone under disturbance state concept.

σmax (MPa)	Model parameter										Fitting effect
	A	B	C	E1 (MPa)	E2 (MPa)	η1 (MPa·N)	η2 (MPa·N)	η3 (MPa·N)	n	m	R^2
35	0.74	0.36	0.31	45.10	52.17	6.42	61998.51				0.992
45	0.09	0.69	0.60	46.39	56.95	3.82	70311.99				0.991
55	84.00	0.04	9.46	12.55	21930.55	2.28	286624.7	5.10	8.9	0.57	0.962