**Concept:**

True strain (**ϵ**_{T}) = \(\ln\left(\frac{A_o}{A_i}\right)=\ln\left(\frac{l_i}{l_o}\right)\)

ϵT = \(\ln\left ( \frac{d_o}{d_i} \right )^2=2\ln\left ( \frac{d_o}{d_i} \right )\)

**Calculation:**

**Given:**

d_{o }= 5 mm, d_{i} = 2 mm

**Then, **

ϵT = \(2\ln\left ( \frac{d_o}{d_i} \right )=2\ln\left ( \frac{5}{2} \right )=1.832\)