Carry out the algebra leading to (8.5.56) and (8.5.57)
8.32 Determine the strain evolution in a material element following the general model in Section 8.5.10 if
the response is elastic-softening with an exponential softening curved = /co. Consider that the element
is subjected to proportional loading with пц — Ian and all the remaining stress components are equal to zero, while єн = є increases inonotonically up to 1.4г<) and then the element is unloaded. Take so — 10f’t/E and
і/ = 0.2.