The relationship between the internal force in an axial member and its deformation can be expressed as:

$\mathrm{\delta }=\frac{\mathrm{FL}}{\mathrm{AE}}$

where
$\mathrm{\delta }$ = deformation,
$\mathrm{F}$ = internal force,
$\mathrm{L}$ = member length,
$\mathrm{A}$ = cross-sectional area, and
$\mathrm{E}$ = elastic modulus.