5.1 Small deformation definition of strain

In an introduction to engineering course, the following description of strain was likely presented:

\[\begin{equation} {\varepsilon}= \lim_{L \rightarrow 0} \frac{\Delta L}{L} \end{equation}\]

• However, this equation is a linear approximation, is one dimensional, and makes a critical assumption of small strains.
• Hence it is inadequate for some important material we will cover this semester.

---