GPa-1
ln D(t) = ln 2 + t/1000
Sample was first equilibrated at 35 C for 48 hours, then stressed at
0.020 GPa until 200 hrs: so stress time is 200-48 = 152 hrs.
ln D(t) = ln 2 + 152/1000
ln D(t) = 0.6931 + 0.1520 = 0.8451
D(t) = 2.328
= 2.328 x 0.020 = 0.0466
Second case: sample was first equilibrated at 70 C for 48 hours, then
stressed at 0.020 GPa until 200 hrs:
ln D(t) = ln 2 + (7.3 x 152)/1000
ln D(t) = 0.6931 + 1.1096 = 1.8027
D(t) = 6.066
= 6.066 x 0.020 = 0.1213
