u/hein21

I am about to perform a random vibration analysis on an trailer.

The excitation spectrum is given in a guideline. This guideline provides different excitation spectra for different vehicles, e.g.:

- (A) Applies to handling and transport by rail, river, sea, air, and road using suitable vehicles on well-maintained roads.

- (B) includes the conditions in the above case, as well as road transport involving the use of unsuitable vehicles and/or poor road conditions, and the handling of trolleys without suspension

As I understand from this definition the guideline provides excitation spectra for products, that are transported in e.g. a vehicle and not for the vehicle itself. Is it still plausible to use the given excitation spectrum as FEA-ready spectrum for my PSD analysis.

If so, do I need to consider local damping of the axes or is this already implicitly considered in the type of the given spectrum (suitable/unsuitable vehicle and good/poor roads)?

A footnote also says: "Low-frequency vibrations occur as part of the noise-like vibrations caused by the suspension systems of land vehicles.", which makes me further believe, that these spectra are not really suitable for a vehicle itself.

I am just trying to get my head around it.

For anyone interested, the given spectrum is the 2M5 spectrum defined in EN IEC 60721-3-2:2018.

I am about to calculate the torsional nominal stress in a double fillet weld.
The distance between the welds (usually the sheet thickness) is pretty large (L >> a) and almost identical to the length of the fillet welds itself.

I thought I might divide the Torque T by the leverage L/2 in order to get a resulting pair of forces and taking into account the forces as shear forces and calculating a stress as shear force per area (a x L). Do you think this is a suitable way to calculate the stress in order to perform a static strength verification with nominal stresses?

Is there another, maybe more correct way to calculate the torsional stress in this case or in general for an "open profile, consisting of two geometries"?