Explain the difference between ''engineering'' true stress and strain.?

Question

Explain the difference between ''engineering'' true stress and strain.?

Answer 1

"Engineering" stress and strain is calculated from simple ratios with the original dimensions of the object. "True" stress and strain are more complicated:

- True stress is the force divided by the deformed area - in tension, this would be larger than engineering stress, as the cross-section shrinks when the force is applied.

- True strain is calculated from the integral of the differential strain, and is thus equal to the logarithm of the ratio of the initial and final lengths (rather than the difference divided by initial length).

True stress and strain are often unnecessary, but in problems with large ("finite") deformations (e.g. when working with rubber) they become necessary.