Strain
Strain tensor can be transformed into $$\tag{1} \mathbf{\varepsilon} = \left[ \begin{array}{c} \varepsilon_{xx} \newline \varepsilon_{yy} \newline \varepsilon_{zz} \newline 2 \varepsilon_{xy} \newline 2 \varepsilon_{yz} \newline 2\varepsilon_{zx} \end{array} \right], $$ that is an expression of symmetric tensor in lower order tensor.For small displacement a strain tensor component $$\tag{1} \begin{array}{rcl} \varepsilon_{ab} & = & \displaystyle \frac{1}{2} \left( \frac{\partial u_a}{\partial x_b} + \frac{\partial u_b}{\partial x_a} + \frac{\partial u_a}{\partial x_b} \frac{\partial u_b}{\partial a} \right), \newline \newline & \approx & \displaystyle \frac{1}{2} \left( \frac{\partial u_a}{\partial b} + \frac{\partial u_b}{\partial a} \right), \end{array} $$ where $u_a$ is displacement in $a$ direction and $x_b$ coordinate in $b$ direction, e.g. $u_1 \equiv u_x$ and $x_3 \equiv z$.A 3D strain tensor $$\tag{1} \mathbf{\varepsilon} = \left[ \begin{array}{ccc} \varepsilon _{xx} & \varepsilon _{xy} & \varepsilon _{xz} \newline \varepsilon _{yx} & \varepsilon _{yy} & \varepsilon _{yz} \newline \varepsilon _{zx} & \varepsilon _{zy} & \varepsilon _{zz} \newline \end{array} \right], $$ where $\varepsilon _{ab}$ ($a = b$) for normal strain, $\varepsilon _{ab}$ ($a \ne b$) for shear strain.It is a scalar representation of strain tensor $$\tag{1} \begin{array}{rcl} \displaystyle \varepsilon_{\rm eqv} & = & \displaystyle \frac{1}{1 + \nu} \left[ \frac{1}{2} (\varepsilon _{xx} - \varepsilon _{yy})^2 + \frac{1}{2} (\varepsilon _{yy} - \varepsilon _{zz})^2 \right. \newline \newline & & \displaystyle \left. +\frac{1}{2} (\varepsilon _{zz} - \varepsilon _{xx})^2 + 3(\varepsilon _{xy}^2 + \varepsilon _{yz}^2 + \varepsilon _{zx}^2) \right] ^{1/2} \end{array} $$ and a straightforward variable reporting strain results over a body.