Torsion (Helical) Spring Calculator implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t5-009

Effect

Computation or source lookup only

Input and validation requirements

Zero wire diameter produces k=0, stress division by zero, and undefined angular deflection; the calculator must reject it. The specification also omits the definition or input source for Kb and does not state whether coil diameter is mean or outside diameter, so finite results are not uniquely determined without assumptions.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "wire_diameter": 2,
    "wire_diameter_unit": "mm",
    "mean_coil_diameter": 20,
    "mean_coil_diameter_unit": "mm",
    "active_coils": 8,
    "E": 200000,
    "E_unit": "N/mm^2",
    "applied_moment": 1000,
    "moment_unit": "N·mm",
    "Kb": 1.15
  },
  "expected_outputs": {
    "spring_rate_Nmm_per_rad": 312.5,
    "bending_stress_MPa": 1464.2255,
    "angular_deflection_rad": 3.2,
    "angular_deflection_deg": 183.3465,
    "angular_deflection_turns": 0.5092958
  },
  "working": "d⁴=2⁴=16. k=Ed⁴/(64DN)=(200000×16)/(64×20×8)=3200000/10240=312.5 N·mm/rad. σ=32KbM/(πd³)=(32×1.15×1000)/(π×2³)=36800/(8π)=4600/π=1464.2255 MPa. θ=M/k=1000/312.5=3.2 rad. θ_deg=3.2×180/π=183.3465°. θ_turns=3.2/(2π)=0.5092958."
}

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