List of symbols

Symbol	Name of the symbol	Unit
$C$	spring index	$\mathrm{ }$
$D$	mean coil diameter	$\mathrm{mm}$
$D$	spring outer diameter	$\mathrm{mm}$
$D_0$	mean coil diameter (vertex)	$\mathrm{mm}$
$D_0$	spring inner diameter	$\mathrm{mm}$
$D_1$	mean coil diameter (base)	$\mathrm{mm}$
$E$	modulus of elasticity	$\mathrm{GPa}$
$E_p$	energy stored	$\mathrm{J}$
$F$	force	$\mathrm{N}$
$G$	shear modulus	$\mathrm{GPa}$
$K_W$	wahl factor	$\mathrm{ }$
$L$	effective spring length	$\mathrm{mm}$
$M$	applied torque moment	$\mathrm{Nm}$
$S_F$	safety factor	$\mathrm{ }$
$S_y$	the minimum yield strength	$\mathrm{MPa}$
$d$	diameter of the spring wire	$\mathrm{mm}$
$f$	spring deflection	$\mathrm{mm}$
$k$	spring stiffness	$\mathrm{N/m}$
$n$	number of active coils	$\mathrm{ }$
$r$	spring length	$\mathrm{mm}$
$δ$	spring thickness	$\mathrm{mm}$
$σ$	tensile stress	$\mathrm{MPa}$
$σ_B$	bending stress	$\mathrm{MPa}$
$σ_{adm}$	material admissible stress	$\mathrm{MPa}$
$τ_S$	shear stress	$\mathrm{MPa}$
$τ_{adm}$	shear admissible stress	$\mathrm{MPa}$
$φ$	spring angular deflection	$\mathrm{°}$