beam_modal
Calculate exact Euler-Bernoulli natural frequencies for a uniform rectangular beam. Serves as a closed-form reference for FEM modal analysis with various boundary conditions.
Instructions
Exact Euler-Bernoulli natural frequencies of a uniform rectangular beam — the
closed-form modal oracle (no solver), and the band the CalculiX fem_modal
eigen-solve is gated against. f_n = (βL)_n²/(2π)·sqrt(E·I/(ρ·A·L⁴)); the beam bends
in height_mm (I = width·height³/12, so a slender beam's lowest mode is the
thinnest-direction bend). boundary: 'cantilever' | 'simply_supported' |
'clamped_clamped' | 'free_free' | 'clamped_pinned' (up to 5 modes each). Material
via youngs_gpa+density_kg_m3, or a Materials-DB material name. Slender-beam
theory — accurate while length ≫ height (thick beams need a Timoshenko correction).
Returns {boundary, n_modes, frequencies_hz, beta_l, first_mode_hz, youngs_gpa, density_kg_m3, area_mm2, I_mm4, slenderness}.
Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| n_modes | No | ||
| boundary | No | cantilever | |
| material | No | ||
| width_mm | Yes | ||
| height_mm | Yes | ||
| length_mm | Yes | ||
| youngs_gpa | No | ||
| density_kg_m3 | No |