Source: https://guthlabs.ai/docs/instruments/thick-wall-cylinder-stress-lame/implementation/

instrument implementation / implementation-contract

# Thick-Wall Cylinder Stress (Lamé) implementation

A source-bound implementation contract for Thick-Wall Cylinder Stress (Lamé); deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## 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**: t6-044

**Effect**: Computation or source lookup only

## Input and validation requirements

The supplied specification has no stated validation for r_o>r_i. Setting r_o=r_i makes the Lamé denominator zero and both stress outputs undefined; the instrument must reject this input rather than plot or return a numeric value.

## 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": {
    "r_i": 50,
    "r_o": 100,
    "p_i": 10,
    "p_o": 0,
    "r": 50,
    "length_unit": "mm",
    "pressure_unit": "MPa"
  },
  "expected_outputs": {
    "sigma_hoop": 16.666667,
    "sigma_radial": -10,
    "max_hoop_stress_in_wall": 16.666667,
    "max_hoop_location": "r_i=50 mm",
    "stress_unit": "MPa"
  },
  "working": "D=r_o²−r_i²=100²−50²=10000−2500=7500 mm². A=(10×2500−0×10000)/7500=25000/7500=3.333333 MPa. B=(2500×10000×(10−0))/7500=250000000/7500=33333.333333 MPa·mm². At r=50 mm, B/r²=33333.333333/2500=13.333333 MPa. Therefore σ_hoop=A+B/r²=3.333333+13.333333=16.666667 MPa; σ_radial=A−B/r²=3.333333−13.333333=−10.000000 MPa. Since B>0, hoop stress decreases with r, so the algebraic maximum is at the inner wall."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/thick-wall-cylinder-stress-lame/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/thick-wall-cylinder-stress-lame/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/thick-wall-cylinder-stress-lame/qualification/>)

## Sources and evidence

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

- `VERIFIED_LEDGER.json`

- `evidence-tranche6/tranche6-results.json`