Fatigue Analysis of Helical Spring Subjected to Multi-axial Load
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Table 1 Standard spring
DIN 2098 specification
Parameter
Symbol and unit
Value
Free length
L f [mm]
110
Maximum displacement
s max [mm]
52.5
Wire size
d[mm]
5
Mean coil diameter
D m [mm]
32
Internal coil diameter
D i [mm]
27
External coil diameter
D o [mm]
27
Maximum spring force
F S.max [N]
1226
Spring rate
R[N/mm]
22.9
Active number of coil
i s
8.5
Total number of coil
i t
10.5
Fig. 1 Spring geometry
Table 2 Chrome-silicon
mechanical property
Parameter
Symbol and unit
Value
Ultimate tensile strength
S u [MPa]
2950
Yield stress
σ y [MPa]
2270
Elastic modulus
E[GPa]
205
Poisson’s ratio
v
0.3
Table 3 Chrome-silicon
strain-life property
Parameter
Symbol and unit Value
Fatigue strength coefficient
σ
f [MPa]
5943.6
Fatigue strength exponent
b
−0.1463
Fatigue ductility coefficient ε
f
0.5828
Fatigue ductility exponent
c
−1.0777
Cyclic strength coefficient
K [MPa]
4086.2
Cyclic Strain exponent
n
0.1251