Source: https://guthlabs.ai/docs/instruments/thermal-stress-calculator/mechanism/

instrument mechanism / verified-clean

# Thermal Stress Calculator mechanism

The inspectable method record for Thermal Stress Calculator, kept separate from implementation and qualification.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Model scope

The honest label correctly states full restraint and linear elasticity but should also disclose the signed-stress convention or explicitly label the result as a stress magnitude, plus the uniform-temperature, isotropic, constant-property, and one-dimensional-restraint assumptions.

- σ=EαΔT is correct for the magnitude of stress under uniform temperature change and complete axial restraint, assuming linear elasticity and constant isotropic properties.

- For a signed stress with tensile stress positive, the standard relation is σ=-EαΔT: heating produces compression and cooling produces tension. The specification does not state whether σ_thermal is signed or a magnitude.

- The model does not state the required assumptions of uniform temperature, isotropic material behavior, temperature-independent E and α over the range, and one-dimensional/full restraint in the expansion direction.

## Units and conventions

- E must be entered in pascals (Pa) for σ_thermal to be returned in pascals.

- α must be entered in reciprocal kelvins (1/K) or reciprocal degrees Celsius (1/°C). Temperature differences in kelvins and degrees Celsius have the same numerical value.

- ΔT must be a temperature difference, defined as final temperature minus initial temperature; it must not be an absolute temperature.

- The CTE table must provide α appropriate to the material and temperature range; using a single constant α is an approximation.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "E": 200000000000,
    "alpha": 0.000012,
    "delta_T": 50,
    "units": "E in Pa; alpha in 1/K; delta_T in K"
  },
  "expected_outputs": {
    "sigma_thermal_Pa": 120000000,
    "sigma_thermal_MPa": 120
  },
  "working": "σ = E × α × ΔT\n= 200,000,000,000 × 0.000012 × 50\n= 2,400,000 × 50\n= 120,000,000 Pa\n= 120 MPa\nLiteral formula result is positive; physically, under tensile-positive convention, restrained heating corresponds to -120 MPa compression."
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

The extreme finite inputs produce a mathematical result of 10^613 Pa, which overflows JavaScript double-precision arithmetic to Infinity. The instrument should reject or range-check nonphysical/extreme inputs rather than present Infinity as a normal stress result.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/thermal-stress-calculator/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/thermal-stress-calculator/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/thermal-stress-calculator/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-tranche4/tranche4-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`