FAST output signals

Hi Jason,

I observer the following output parameters in the FAST manual (Table 42). The tower side-to-side shear force is not in the same direction as the side-to-side bending moment (along yt axis)?

TwrBsFyt, Tower base side-to-side shear force, Directed along the yt-axis, (kN)
TwrBsMxt, Tower base roll (or side-to-side) moment (i.e., the moment caused by side-to-side forces), About the xt-axis, (kN·m)


Dear Xiao.Wang

What is called “side-to-side” in wind energy nomenclature are the loads resulting from transverse forces nominally parallel to the rotor (yt). Thus, the “side-to-side” moment is nominally about the axis normal to this i.e. nominally about the rotor axis (xt).

I hope that helps.

Best regards,