Source: https://guthlabs.ai/docs/instruments/rotating-unbalance-force-calculator/
instrument / verified-clean
# Rotating Unbalance Force Calculator
The current ledger marks this instrument verified clean within the source-bound verification corpus.
Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**
## Inspectable records
[01**Overview**Purpose and lifecycle]()[02**Mechanism**Method and assumptions]()[03**Implementation**Binding and validation]()[04**Qualification**Evidence and errata]()
## Ledger state
The current ledger marks this instrument verified clean within the source-bound verification corpus.
**Area**: Mechanical, Civil & Structural Engineering — Statics/Dynamics, Strength of Materials, Machine Design, Civil, HVAC, Vibration
**Tranche**: tranche-5
**Evidence ID**: t5-104
**Ledger rows**: 1
No ledger note is attached.
## Review findings
The formulas are conditionally standard, but the specification is not implementation-ready because M, r, ω_n, and ζ are undefined and the symbol m is reused for different masses. The empty honest_label should be replaced with a clear statement that this is an ideal linear SDOF steady-state model, that angular speed must be supplied in rad/s or explicitly converted, and that resonance behavior is model-dependent.
### Formula and scope findings
- F0=m e ω² is the standard rotating-unbalance force-amplitude formula, but the notation "me" is ambiguous and must explicitly mean unbalance mass m_u multiplied by eccentricity e.
- The displacement formula is standard for a linear single-degree-of-freedom system only when M is the total participating system mass, r=ω/ω_n, ω_n=√(k/M), and ζ=c/(2Mω_n). These definitions are absent.
- The input description uses m for both unbalance mass and system mass, while the displacement formula uses M. The two masses must be distinct and explicitly named.
- The formula computes steady-state displacement amplitude under harmonic rotating-unbalance excitation; it does not by itself provide phase, transient response, or vibration velocity/acceleration.
- The formula must state that k is positive and that the model is linear SDOF. For an undamped system at r=1, the steady-state amplitude is unbounded rather than finite.
### Unit assumptions
- Unbalance mass m_u and system mass M are in kilograms.
- Eccentricity e is in metres.
- Rotor angular speed ω is in radians per second, not revolutions per minute.
- Stiffness k is in newtons per metre and damping c is in newton-seconds per metre.
- F0 is in newtons and X is a displacement amplitude in metres.
- The system mass M is the total modal or participating mass used in ω_n=√(k/M).
## Boundary hardening
**BREAK_CLAIMED** · SELF_FLAGGED
The ideal undamped resonance input r=1 and ζ=0 produces a zero denominator and an undefined steady-state amplitude. A second hazard is that negative eccentricity has incompatible magnitude-versus-direction interpretations.
## Errata and corrections
No applied erratum is attached to this unique-name record.
## Inspectable example
4 review vectors are recorded. One source-bound sample is shown below.
````
{
"inputs": {
"unbalance_mass_kg": 0.02,
"eccentricity_m": 0.001,
"omega_rad_s": 100,
"system_mass_kg": 10,
"stiffness_N_per_m": 10000,
"damping_Ns_per_m": 20
},
"expected_outputs": {
"F0_N": 0.2,
"steady_state_amplitude_X_m": 0.00000222167
},
"working": "ω_n=√(k/M)=√(10000/10)=√1000=31.6228 rad/s. r=ω/ω_n=100/31.6228=3.16228, so r²=10. ζ=c/(2Mω_n)=20/(2×10×31.6228)=0.0316228. F0=m_u e ω²=0.02×0.001×100²=0.2 N. Numerator for X=(m_u e/M)r²=(0.02×0.001/10)×10=0.00002 m. Denominator=√[(1−10)²+(2×0.0316228×3.16228)²]=√[81+0.04]=√81.04=9.00222. X=0.00002/9.00222=0.00000222167 m."
}
````
## Related workflows
No source-defined multi-instrument workflow membership is recorded.
## Sources and evidence
These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.
- `VERIFIED_LEDGER.json · VERIFIED_CLEAN`
- `evidence-tranche5/tranche5-results.json`
- `BOUNDARY_HAZARD_CATALOG.json`