Rigid-body 6-DOF natural frequencies and mode shapes for a mass mounted on an arbitrary number of vibration isolators.
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Moments of inertia are about the CG, assumed aligned with the global X/Y/Z axes (no products of inertia). Use CAD mass properties for best accuracy.
Box envelope is for the 3D view only — it doesn't affect the analysis. Set it to your actual enclosure dimensions, centered on the CG above.
Isolators
8 isolators
#
X (in)
Y (in)
Z (in)
kx (lb/in)
ky (lb/in)
kz (lb/in)
Enter each isolator's mounting location and per-axis spring rate. Locations are in the same reference frame as the CG above — not pre-offset to the CG. The tool does that translation for you.
Enter your isolator layout and click Compute modes to see natural frequencies, mode shapes, and the CG–isolator offset diagnostic.
3D Configuration & Mode Shapes
drag to orbit · select a mode to animate it
Static configuration — drag to rotate
Mode animations exaggerate displacement for visibility and play at a fixed illustrative rate — not the true modal frequency (up to a few hundred Hz, far too fast to watch). Ground springs are drawn schematically to show relative compression/extension, not to scale.
Random Vibration Response
input PSD vs. isolated response, log–log
Freq (Hz)
PSD (g²/Hz)
Breakpoints define the input PSD as piecewise log–log segments — the same convention used in MIL‑STD/qualification random-vibration specs. The default curve is illustrative only; replace it with your actual test spec.
Click Compute response to generate the transfer function.
Model: a rigid, non-rotating base translates uniformly along the chosen axis; the response is the full 6–DOF modal transmissibility (relative-coordinate base-excitation form, summed over all 6 modes with a single global damping ratio) evaluated at the CG and at one box corner, so any amplification from rocking modes shows up as extra response away from the CG. This is a linear, steady-state PSD analysis — it does not check for isolator stroke/clearance limits or nonlinear bottoming.