Basic symbols

Symbol Name of the symbol Unit
$ $bolt$\mathrm{ }$
$A_b$cross‐sectional area of the bolts$\mathrm{mm^2}$
$C_1$coefficient $ C_1 $ $\mathrm{}$
$C_2$coefficient $ C_2 $ $\mathrm{}$
$C_3$coefficient $ C_3 $ $\mathrm{}$
$C_4$coefficient $ C_4 $ $\mathrm{}$
$C_c$coefficient according to load$\mathrm{ }$
$D$diameter of the shaft$\mathrm{mm}$
$D$basic major diameter of internal thread (nominal diameter)$\mathrm{mm}$
$D$diameter, larger diameter$\mathrm{mm}$
$D_1$basic minor diameter of internal thread$\mathrm{mm}$
$D_2$basic pitch diameter of internal thread$\mathrm{mm}$
$H$height of fundamental triangle$\mathrm{mm}$
$H$width, larger width$\mathrm{mm}$
$H$geopotential altitude$\mathrm{m}$
$H_b$lower limit geopotential altitude$\mathrm{m}$
$H_p$pressure scale height$\mathrm{m}$
$K_t$stress concentration factor$\mathrm{ }$
$K_{tg}$stress concentration factor with the nominal stress based on gross area$\mathrm{ }$
$K_{tn}$stress concentration factor with the nominal stress based on net area$\mathrm{ }$
$K_{ts}$stress concentration factor for shear stress$\mathrm{ }$
$M$air molar mass at sea level$\mathrm{kg\cdot kmol^{-1}}$
$N_A$Avogadro constant$\mathrm{kmol^{-1}}$
$P$load, force$\mathrm{N}$
$P_{all-B}$allowable bearing stress$\mathrm{MPa}$
$R$specific gas constant$\mathrm{J\cdot K^{-1}\cdot kg^{-1}}$
$R^*$universal gas constant$\mathrm{J\cdot K^{-1}\cdot kmol^{-1}}$
$S$Sutherland's empirical coefficients $ S $ $\mathrm{K}$
$S_F$safety factor$\mathrm{ }$
$S_{y}$the minimum yield strength$\mathrm{MPa}$
$T$temperature $ T $ $\mathrm{K}$
$T_b$lower limit temperature$\mathrm{K}$
$a$speed of Sound$\mathrm{m/s}$
$b$width key$\mathrm{mm}$
$d$basic major diameter of external thread (nominal diameter)$\mathrm{mm}$
$d_1$basic minor diameter of external thread$\mathrm{mm}$
$d_2$basic pitch diameter of external thread$\mathrm{mm}$
$d_3$basic smaller diameter of external thread$\mathrm{mm}$
$g$gravitational acceleration$\mathrm{m/s^2}$
$h$height key$\mathrm{mm}$
$h$height above sea level$\mathrm{m}$
$l$mean free path of air particles$\mathrm{m}$
$l$length key$\mathrm{mm}$
$l_t$tolerance of key length$\mathrm{mm}$
$n$air number density$\mathrm{m^{-3}}$
$p_b$lower limit pressure$\mathrm{Pa}$
$p_{air}$atmospheric pressure air$\mathrm{Pa}$
$r$nominal earth's radius$\mathrm{m}$
$r$radius of curvature of hole, arc, notch$\mathrm{mm}$
$r_1$max. rounding the key$\mathrm{mm}$
$r_2$groove rounding$\mathrm{mm}$
$t$depth in the shaft$\mathrm{mm}$
$t$depth of groove, notch$\mathrm{mm}$
$t_1$depth in the hub$\mathrm{mm}$
$t_t$tolerance of the groove height in the shaft$\mathrm{mm}$
$t_{1t}$tolerance of the groove height in the hub$\mathrm{mm}$
$v̄$mean air-particle speed$\mathrm{m/s}$
$β$temperature gradient $ β $ $\mathrm{K\cdot m^{-1}}$
$β_s$Sutherland's empirical coefficients $ β_s $ $\mathrm{kg\cdot m^{-1}\cdot s^{-1}\cdot K^{-1/2}}$
$γ_{air}$specific weight air$\mathrm{kg\cdot m^{-2}\cdot s^{-2}}$
$κ$adiabatic index$\mathrm{ }$
$λ$thermal conductivity$\mathrm{W\cdot m^{-1}\cdot K^{-1}}$
$μ$dynamic viscosity$\mathrm{kg\cdot m^{-1}\cdot s^{-1}}$
$ν$kinematic viscosity$\mathrm{m^2\cdot s^{-1}}$
$ρ_{air}$density air$\mathrm{kg/m^3}$
$σ$effective collision diameter of an air molecule$\mathrm{m}$
$σ$normal stress$\mathrm{MPa}$
$σ_{all-A}$allowable axial stress$\mathrm{MPa}$
$σ_{all-B}$allowable bending stress$\mathrm{MPa}$
$σ_{all-C}$allowable combined stress$\mathrm{MPa}$
$σ_{max}$maximum normal stress$\mathrm{MPa}$
$σ_{nom}$nominal or reference normal stress$\mathrm{MPa}$
$τ_{all-S}$allowable shear stress$\mathrm{MPa}$
$τ_{max}$maximum shear stress$\mathrm{MPa}$
$τ_{nom}$nominal or reference shear stress$\mathrm{MPa}$
$ω$air-particle collision frequency$\mathrm{Hz}$