Johnson Parabolic Formula (Intermediate Columns) 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

t4-118

Effect

Computation or source lookup only

Input and validation requirements

The zero-modulus input makes the Johnson expression and critical slenderness ratio undefined through division by zero. The instrument should explicitly reject E = 0 rather than return a numeric critical stress.

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": {
    "yield_strength": {
      "value": 250,
      "unit": "MPa"
    },
    "elastic_modulus": {
      "value": 200000,
      "unit": "MPa"
    },
    "slenderness_ratio_KL_over_r": 0
  },
  "expected_outputs": {
    "critical_stress": {
      "value": 250,
      "unit": "MPa"
    },
    "critical_slenderness_ratio": 125.663706,
    "applicable_to_strict_less_than_range": true
  },
  "working": "Cc=√(2π²E/σy)=√(2π²×200000/250)=√(1600π²)=40π=125.663706. σcr=σy−[σy²/(4π²E)](KL/r)²=250−[250²/(4π²×200000)]×0²=250−0=250 MPa. Since 0<125.663706, the Johnson range check is true."
}

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-tranche4/tranche4-results.json