Table 1.

Fatigue loading groups examined for mechanical properties, SHG, and TEM. All groups underwent mechanical testing except control and the 1.0%, 300 cycle group which was TEM imaged only (++). Groups with SHG imaging and analysis (*) and TEM imaging (+) are denoted.

Load Level	Cycle Number	Sample Size
Control	0*+	N = 49, N* = 6, N+ = 4
Toe Region	500	N = 12
0.5% Strain
Linear Region	300++, 500*	N = 12, N* = 10, N++ = 3
1.0% Strain
Plastic Region	50, 200, 300, 500	N = 12/group
1.5% Strain
Post-Plastic	50*+, 100,200,300*+,	N = 12/group, N* = 10/group,N
Region	400, 500*	+=2–4/group
2.5% Strain