Factor of Safety / Allowable Stress Calculator mechanism

Model scope

The two stated formulas are arithmetically standard under explicit strength-selection and unit-consistency assumptions, but the spec is incomplete because it claims required-section sizing without a sizing formula and does not define the yield-versus-ultimate criterion. The empty honest_label should be replaced with a limitation statement identifying this as a basic stress-ratio calculator, not a complete structural or machine-design sizing/code-compliance tool.

• SF=σ_strength/σ_actual is the standard basic factor-of-safety formula when σ_strength is explicitly selected as yield or ultimate strength and both stresses use the same basis and units.
• σ_allow=σ_yield/SF is correct for an allowable stress based on yield strength; using ultimate strength instead requires an explicitly selected design criterion and may not be appropriate for ductile-material yielding checks.
• The claimed 'required section' computation has no formula or required inputs for load, geometry, section properties, or stress relationship, so that capability is unspecified and cannot be verified.
• The spec does not unambiguously define whether the strength input is yield strength or ultimate strength, nor which criterion is the default.

Units and conventions

• σ_strength and σ_actual must represent the same stress type and use compatible units; the units cancel in SF.
• For σ_allow, σ_yield and target SF must be supplied with a positive target SF; σ_allow has the same stress units as σ_yield.
• No automatic conversion between Pa, kPa, MPa, psi, or other stress units is stated.
• Stress sign conventions and whether tensile, compressive, shear, or equivalent stress is intended are unspecified.

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "mode": "SF",
    "strength_type": "yield",
    "strength": 250,
    "strength_unit": "MPa",
    "actual_stress": 100,
    "actual_stress_unit": "MPa"
  },
  "expected_outputs": {
    "SF": 2.5
  },
  "working": "SF = σ_yield / σ_actual = 250 MPa / 100 MPa = 2.5. The MPa units cancel."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

A zero target safety factor produces division by zero and must be rejected. The signed-stress probe also exposes a convention hazard: literal arithmetic gives a negative safety factor, whereas the usual engineering interpretation uses stress magnitude.

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche5/tranche5-results.json
• BOUNDARY_HAZARD_CATALOG.json