and knowing that the stages are defined

linear σ=Eε

uniform plastic σ=Kδ

^{2}

necking σ=αδ

where ε is an elastic strain and δ plastic strain

find the values of the constants E K n α

using the given data i plotted σ(ε) and got the following

now to find the constant E, i take the linear portion and find its incline, i get

E=33.33MPa

as for the others

for the platic deformation, can i take an of the points after (3,9) ?

for each point i chose i get a different value

K=σ/δ

^{2}

K=4e4/(13e-4)

^{2}=2.366864e10

K=4.5e4/(20e-4)

^{2}=1.125e10

is the necking portion not meant to be after a maximum point in the graph? in this graph i have no such point.