E	Elastic modulus of the backing plate material
σy	Yield strength of the backing plate material
ρ	Density of the backing plate material
δb	Thickness of the backing plate
$E_0$	Basic protection efficiency of the armor ceramic
$E_{cmax}$	Maximum protection efficiency of the armor ceramic
${\delta }_{bcr}$	Minimum backing plate thickness for $E_{cmax}$
$k_{c1}, k_{c2}$	Support coefficient, without specific physical meaning
${\rho }_{cr}$	Minimum backing plate density for $E_{cmax}$
$k_m$	Inertial support coefficient
$k_F$	Mechanical support coefficient
$\mathrm{S}$	Inertial support
$S_{cr}$	Minimum inertial support for maximum energy consumption of armored ceramics
ε 0	The strain that limits the effect of the mechanical support
σ	The backing plate stress at ε0
σcr1, σcr2	The upper and lower limit within which the change of mechanical support can influence the protection efficiency of armor ceramic