Karamba3D is capable of calculating the natural vibration modes and frequencies of structures (see section 3.5.7). For results to match reality the inertia properties of a structure need to be modelled correctly. Masses of elements (e.g. beams, trusses, shells) are automatically taken care of. All other items need to be included via point-masses.
Be aware of the fact that masses defined with the “Point-Mass”-component do not have a weight but inertia only! They also do not add to the mass of a model as output at the "Assemble"-component.
Thus they effect only the calculation of natural frequencies. The “Point-Mass” component expects a mass in kilogram at its input-plug “Mass” (see fig. 184.108.40.206). Nodes where masses shall sit can be identified by supplying node indexes or positions (just like for point-loads). Point masses get displayed as green spheres. Their diameters result from the volume calculated as mass divided by density. The latter defaults to
(steel) and can be provided at the input-plug-“rho”.
Fig. 220.127.116.11: Vibration mode of beam with point mass in the middle