Question on true strain- experimental reading
Question on true strain - experimental reading
I have an experimental set of readings from elsewhere performed on a tension tets on steel specimen.
I have the initial area and final area (area at the point at which specimen just breaks).
I see that true strain = ln (1 + epsilon) where epsilon is engineering/nominal strain
This is through all the set of readings except the last reading.This is fine.
The last reading just befor the specimen breaks has the final area measured.
And the ratio between initial and final area is 2.14
The last reading for true strain is given as formula:ln( 1+1.14)
I guess from reading of all other speciment that 1.14 = (ratio between initial and final area -1)
I'm sure I'm mssing a basic- can anyone tell how this formula is obtained from mechanics?