**3. Results**

As can be observed in durability results plotted (damage) on the sub-frame, the performances were practically indistinguishable among the three techniques. Because of the low compliance of the structure, the dynamic impact of the loading input is low, and accordingly, all techniques merged to an akin answer, as far as damage magnitude, yet additionally, damaged regions.

For the torsion axle, there was a bigger contrast, because of the dynamic influence. Its mechanism-like characteristic has a higher structural compliance, presenting higher deflections and relative movements between the interface points when submitted to loading. Also, its lower stiffness properties induce it to be more susceptible to dynamic influence as already explained. Due to that, a contrast between the static and dynamic durability assessment can be observed. It is usually hard to decide the significance of variations in fatigue results, for instance, if we accept we are managing a material that has a correspondent stress/strain-life slant of around 10, then we can convert the life or damage differences into stress/strain difference. In other words, we can assume the following relationship:

Damage variation = (damage to be compared/damage baseline)^.1

For instance, for the torsion axle, the static damage result is 38, and transient in frequency domain is 68, and in transient time domain is 198. If we consider the static as a baseline (since it is the lowest value), we can expect the following damage variation: 6% increase of damage for transient frequency domain and 11% increase of damage for transient time domain when compared to static.

**Figure 10.** *Static load history damage result plot. Maximum damage = 38.*

**Figure 11.** *Time domain modal superposition damage result plot. Maximum damage = 198.*

**Figure 12.** *Frequency domain modal superposition damage result plot. Maximum damage = 68.*

When calculating damage using the static method, the dynamic effects are not considered, and accordingly, the result is the lowest among the other methods introduced. The transient method in time domain shows the higher damage.

**Figure 13.** *Static load history damage result plot. Maximum damage = 119.*

**Figure 14.** *Time domain modal superposition damage result plot. Maximum damage = 116.*

**Figure 15.** *Frequency domain modal superposition damage result plot. Maximum damage = 92.*

The most damaged regions are also different among the three approaches on the torsion axle. It is possible to observe that the center was the most damaged region in all methodologies; however, the most critical elements are different. This suggests that these various approaches can point various conclusions as far as magnitude as well as most damaged regions (**Figures 10–15**).
