Source: https://guthlabs.ai/docs/instruments/welded-joint-strength-calculator/mechanism/

instrument mechanism / verified-clean

# Welded Joint Strength Calculator mechanism

The inspectable method record for Welded Joint Strength Calculator, kept separate from implementation and qualification.

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

## Model scope

The direct fillet-weld shear equation is conditionally standard, but the instrument specification is incomplete and ambiguous for its advertised scope. It needs explicit definitions for h, L, groove-weld throat, eccentric-load and weld-group formulas, combined-stress treatment, unit conversion, and the source and applicability of allowable weld stresses before it can be verified as a complete calculator.

- The formula τ=F/(0.707h·L) is valid only for nominal direct shear in a uniform fillet weld when h is the fillet leg size, the two legs are approximately equal, and L is the effective weld length. If h already means effective throat, multiplying by 0.707 is incorrect.

- The specification claims fillet and groove weld calculations, but the supplied throat formula is only applicable to an equal-leg fillet weld. Groove-weld effective throat requires joint geometry and weld preparation details.

- No actual formulas are supplied for eccentric loading, bending, or torsion. Unit properties Iu and Ju alone are insufficient without equations such as stress from moment divided by weld-group distance and unit-property-based torsional stress.

- Combined direct shear, bending, and torsional stresses are not defined, including whether components are vectorially combined, algebraically combined, or checked separately.

- The required allowable-stress input is omitted from the listed inputs even though safety factor output requires SF=allowable weld stress/actual stress.

- The term 'AWS allowable weld stress' is ambiguous without specifying the AWS code edition, electrode classification, base-metal strength, weld type, loading mode, and whether the allowable is nominal, resistance-based, or factored.

## Units and conventions

- For the metric vectors, F is in newtons and h and L are in millimetres, producing τ in N/mm², numerically equal to MPa.

- For the inch-pound vector, F is in lbf and h and L are in inches, producing τ in lbf/in², numerically equal to psi.

- h is assumed to be the equal-leg fillet weld leg size, not the already-computed effective throat.

- L is assumed to be the effective load-carrying weld length, excluding ineffective end returns or discontinuities.

- Allowable stress must use the same stress units as the calculated τ.

- The direct-load formula assumes uniform load distribution, a static load, a straight weld, and no stress-concentration, residual-stress, fatigue, buckling, or deformation checks.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "load_type": "direct shear",
    "F": 10000,
    "F_units": "N",
    "h": 6,
    "h_units": "mm",
    "L": 100,
    "L_units": "mm",
    "allowable_weld_stress": 180,
    "allowable_units": "MPa"
  },
  "expected_outputs": {
    "tau": 23.5738,
    "tau_units": "MPa",
    "SF": 7.6356
  },
  "working": "Effective throat = 0.707×h = 0.707×6 = 4.242 mm. Effective throat area = 4.242×100 = 424.2 mm². τ = F/area = 10000/424.2 = 23.5738 N/mm² = 23.5738 MPa. SF = allowable/τ = 180/23.5738 = 7.6356."
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

The zero weld-size input produces a division-by-zero undefined result and must be rejected. The zero-load case also exposes an infinite, non-finite safety-factor representation. In addition, signed-load handling is convention-dependent unless the interface explicitly distinguishes direction from stress magnitude.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/welded-joint-strength-calculator/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/welded-joint-strength-calculator/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/welded-joint-strength-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-tranche5/tranche5-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`