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Symbols and units commonly used in springs

Dec 06, 2016

Symbols and units commonly used in springs:

A――Section area of spring material(mm²)

d――Spring material diameter(mm)
E――Spring modulus(MPa)
F――Spring load(N)
F'――Spring Stiffness (N/mm)

Fj――Working limit load of spring(N)
Fo――Initial tension of a cylindrical tensile spring(N)
Fr――Spring radial load(N)
F'r――Radial stiffness of spring(N/mm)
Fs――Spring test load(N)
f――Spring deformation(mm)
fj――Deformation of 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――The tensile spring corresponds to the assumed deformation of the tensile strain Fo.(mm);Center deformation of diaphragm(mm)
G――Shear modulus of materials(MPa)
g――Acceleration of gravity  g=9800mm/s²
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 cone height of disc spring(mm)
I――Inertial moment(mm4)
Ip――Polar moment of inertia(mm4)
K――Coefficient of curvature
Kt――Temperature correction coefficient
ρ――Density of materials(kg/mm³)
σ――Positive stress in spring(Mpa)
σb――Tensile strength of materials(Mpa)
σj――Working ultimate stress of materials(Mpa)
σs――Tensile yield point of material(Mpa)
τ――Spring Shear stress under working(Mpa)
k――Coefficient
L――Expansion length of spring material(mm)
l――Effective working cycle of spring material(mm);Plate spring free chord length(mm)
M――Bending moment(N?mm)
m――Quality of an object Acting on a spring(kg)
ms――The mass of a spring(kg)
N――Variable load cycle times
n――Number of working coils

nz――Number of supporting coils
n1――Total number of coils
pˊ――Single coil Stiffness of spring(N/mm)
R――Middle radius of coil(mm)
R1――Inner radius of coil(mm)
R2――Outer radius of coil(mm)
r――Damping coefficient
S――safety factor
T――Torque(N/mm)
Tˊ――(N·mm/(º))
t――Pitch of spring
tc――Steel cable pitch(mm)
U――Deformation energy(N·mm);(N·mm·rad)
V――Volume of spring(mm³)
v――Velocity of impact body(mm/s)
Zm――Bending section coefficient(mm³)
Zt――section modulus in torsion(mm³)
α――Helix angle(º)
β――Steel cable twist angle(º);Cone semiangle(º)
δ――Axial clearance of coil(mm)
δr――Radial clearance of combined coil(mm)
ζ――coefficient
η――coefficient
θ――Twist angle of torsion bar unit length(rad)
κ――coefficient
μ――Poisson's ratio; Length coefficient
ν――Self vibration frequency of spring(Hz)
Vr――Excitation frequency of variable load of spring(Hz)
τb――Shear strength of materials(Mpa)
τj――Working limit shear stress of spring(Mpa)
τo――The fatigue limit of the material(Mpa)
τs――Material anti torsion yield point(Mpa)
τ-1――Symmetric cyclic torsion fatigue limit of material(Mpa)
φ
――Torsional deflection angle(º);(rad)