Common symbols and units of spring

A — sectional area of spring material (mm 2); equivalent bending stiffness (n / mm); coefficient
A-side length of distance section material perpendicular to spring axis (mm); coefficient
B — bending stiffness of plate (n / mm); coefficient
B — height diameter ratio; side length of distance section material parallel to spring axis (mm); coefficient
C — spiral spring winding ratio; disc spring diameter ratio; coefficient
D — spring pitch diameter (mm)
D1 — inner diameter of spring (mm)
D2 — spring outer diameter (mm)
D — diameter of spring material (mm)
E — spring modulus (MPA)
F — load of spring (n)
F ‘- stiffness of spring
FJ — working limit load of spring (n)
Fo — initial tension of cylindrical tension spring (n)
Fr — radial load of spring (n)
F’r — radial stiffness of spring (n / mm)
FS — test load of spring (n)
F — deformation of spring (mm)
FJ — deformation under working limit load FJ (mm)
Fr — static deformation of spring (mm)
FS — deformation of spring under test load fs (mm); linear static deformation (mm)
Fo — assumed deformation of tension spring corresponding to tension fo at the position (mm); central deformation of diaphragm (mm)
G — shear modulus of material (MPA)
G — acceleration of gravity, g = 9800mm / S
H — working height (length) of spring (mm)
Ho — free height (length) of spring (mm)
HS — height (length) of spring under test load (mm)
H — inner load cone height of disc spring (mm)
I — moment of inertia (MM4)
IP polar moment of inertia (MM4)
K — curvature coefficient; coefficient
KT — temperature correction coefficient
ρ — density of material (kg / mm 3)
σ — normal stress of spring in operation (MPA)
σ B — tensile strength of material (MPA)
σ J — working limit stress of material (MPA)
σ s — tensile yield point of material (MPA)
τ — shear stress of spring in operation (MPA)
K — coefficient
L — developed length of spring material (mm)
L — the effective working ring development length of spring material (mm); the free chord length of leaf spring (mm)
M — bending moment (n · mm)
M — mass acting on the spring (kg)
MS — mass of spring (kg)
N — variable load cycles
N — number of working coils of spring
NZ — number of supporting rings of spring
N1 — total number of coils of spring
P ˊ – stiffness of single coil of spring (n / mm)
R — middle radius of spring coil (mm)
R1 — inner radius of spring coil (mm)
R2 — outer radius of coil (mm)
R — damping coefficient
S — safety factor
T — torque; torque (n · mm)
T ˊ – torsional stiffness (n · mm / (o))
T — pitch moment of spring
TC — pitch of steel cable (mm)
U — deformation energy (n · mm); (n · mm · RAD)
V — volume of spring (mm 3)
V — velocity of impactor (mm / s)
ZM — bending section coefficient (mm 3)
ZT — Torsional section coefficient (mm 3)
α – helix angle (o); coefficient
β – twist angle of steel cable (o); half angle of cone (o); coefficient
δ — axial clearance of spring coil (mm)
δ R — radial clearance of combined spring coil (mm)
ζ — coefficient
η – coefficient
θ — torsion angle per unit length of torsion bar (RAD)
κ – coefficient
μ — Poisson’s ratio; length coefficient
ν — natural frequency of spring (Hz)
VR — excitation frequency of variable load on spring (Hz)
τ B — shear strength of material (MPA)
τ J — working limit shear stress of spring (MPA)
τ O — pulsating torsional fatigue limit of materials (MPA)
τ s — Torsional yield point of material (MPA)
τ – 1 — symmetric cyclic torsional fatigue limit of materials (MPA)
φ — torsional deformation angle (?); (RAD)