2.6 Analysis of strain
Analysis of strains at a point using the Mohr circle of strain is similar to that for stress,
but there are a few points to note about strains. Firstly, while it is possible to talk about
a state of stress with respect to zero stress (taken as atmospheric pressure), there is no
absolute zero for strain so we have to talk about changes, or increments, of strain.
These may be small increments (denoted by δε) or large increments (denoted by ε)
and generally they occur as a result of corresponding large or small increments of stress.