# C'est la Vie – comme ci comme ça

## September 9, 2010

### 卢森堡（124）- principal strains

Filed under: Study and Work — hitzws @ 8:33 PM

The principal strains are calculated from the strain components by the cubic equation:

$\left| \begin{array}{ccc} \varepsilon_x - \varepsilon_0 & 1/2\varepsilon_{xy} & 1/2\varepsilon_{xz} \\ 1/2\varepsilon_{xy} & \varepsilon_y - \varepsilon_0 & 1/2\varepsilon_{yz} \\ 1/2\varepsilon_{xz} & 1/2\varepsilon_{yz} & \varepsilon_z - \varepsilon_0 \end{array} \right| = 0$

where $\varepsilon_0$ = principal strain (3 values)

The three principal strains are labeled ε1, ε2, and ε3. The principal strains are ordered so that ε1 is the most positive and ε3 is the most negative.