Strain

Strain, abbreviated as \(\epsilon\) (Greek symbol epsilon), a dimensionless number, also known as linear strain or longitudinal strain, is the deformation, stretched or compressed, of a material compared to its original length.

 

strain Types

• Elastic Strain  -  A transitory dimensional change that exists only while the initiating stress is applied and disappears immediately upon removal of the stress.

• Plastic Strain  -  A dimensional change that does not go away when the initiating stress is removed.

 

strain formula
\(\large{ \epsilon = \frac{ \Delta l }{ l_i }  }\) \(\large{ \epsilon = \frac{ l_f \;-\; l_i }{ l_i }  }\)
Symbol	English	Metric
\(\large{ \epsilon }\)  (Greek symbol epsilon) = strain	\(\large{\frac{in}{in}}\)	\(\large{\frac{mm}{mm}}\)
\(\large{ \Delta l }\) = length change	\(\large{ ft }\)	\(\large{ m }\)
\(\large{ l_f }\) = final length	\(\large{ ft }\)	\(\large{ m }\)
\(\large{ l_i }\) = initial length	\(\large{ ft }\)	\(\large{ m }\)