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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)