SS-V: 7000 SN Uniaxial Fatigue

Test No. VF01 Find the Fatigue life when a constant amplitude Stress-Life analysis is performed.


A stepped shaft with fillet is subjected to axial loading.

The units are SI.

Figure 1.

Dimensions: D = 120 mm, d = 60 mm, r = 3 mm

The material properties are:
Modulus of Elasticity
2.03e11 pa
Poisson's Ratio
Ultimate Tensile Stress (UTS)
8.63e8 pa
Fatigue Strength Coefficient (SR1)
1.101e9 pa
First Fatigue Strength Exponent (b1)
Cycle Limit of Endurance for 1 Segment SN Curve (NC1)
1e6 cycles
Loading from structural analysis follows the below variation over time:
Table 1. Fatigue Analysis Load History
Time [sec] Amplitude Factor
0 0
1 250
2 0
3 -250
4 0
Figure 2.

No modifying factors (Surface Roughness and Fatigue Strength Reduction factor) are used.


The following image and table show the fatigue life at points A and B.
Figure 3.

Coordinates [mm] Reference [Target Value]* SimSolid % Difference
Point A (-127.586, -2.79319, -1.48875) 3380 3340 -1.2%
Point B (-85.7703, -16.8757, -1.48566) 4840 4725 -2.4%

*The SimSolid results are compared with efatigue calculator.