Verified calculation capability

Principal section modulus Calculation Capability

Elastic section modulus about the principal axes. S1 = I1/c1 and S2 = I2/c2 after the principal-moment engine. Not Sx and Sy, and not bending stress.

Mechanical · Statics Capability ID mechanical.statics.principal_section_modulus version 1.0.0 UNPUBLISHED

Model

I1 axis

I1 axis: S1 = I1 / c1
I2 axis: S2 = I2 / c2

Inputs / Outputs

Canonical symbols for this capability. Agent schemas remain the contract.

Symbol	Quantity	Unit	Role
`parts`	Rows Ix,Iy,Ixy,A,x,y	—	input
`c1`	Distance from the centroid to the extreme fiber along the I1 axis	—	input / output
`c2`	Distance from the centroid to the extreme fiber along the I2 axis	—	input / output
`area`	—	—	output
`x`	—	bar	output
`y`	—	bar	output
`I1`	—	—	output
`I2`	—	—	output
`theta_deg`	—	—	output
`S1`	—	—	output
`S2`	—	—	output
`n`	—	—	output
`model`	—	—	output
`solver`	—	—	output

Assumptions / Validity

Declared scope for this capability. Do not use it outside this domain.

Assumptions

S1 = I1/c1 and S2 = I2/c2 along the principal axes
c1 and c2 are distances from the composite centroid to the extreme fiber
A blank distance omits that modulus
θ is the I1 axis, CCW from +x, in (−90°, 90°]
Not Sx or Sy, bending stress, plastic modulus, or beam deflection

Example

One numerical check. The calculator page holds worked steps and FAQ.

parts=4,1,0,2,0,0 c1=2 c2=1 → S1=2, S2=1, θ=0

Open this example in the calculator

Trust

Review-policy: engine tested — automated tests, sources, version lock, and evidence published. Supplemental to CVP; not Domain Expert Review. See CVP and Review policy.

Tier: Engine tested — catalog token engine_tested
Calculation version: 1.0.0
Evidence tests: 6/6 calculation tests · golden 2/2 · boundary 4/4 · property 0/0
Engine tested: Yes
Source checked: Yes
Supplemental domain review: Not performed
Named expert review: Not performed
Version lock: Supported (409 VERSION_MISMATCH)
Artifact consistency: Build verified · 1.0.0 (workspace artifacts agree)

Production attestation: Embedded snapshot: unpublished · Build schema 1.0.0 ready · Semantic contract ✓ · Attestation report not published on origin · Live production status STALE (3 capabilities; 189 remain CURRENT) @ 2026-09-23T10:40:38.140Z
Semantic contract: PASS
Evidence attested at: 2026-09-23T02:27:54.588Z
Last production check: 2026-09-23T02:27:54.588Z
Public / cache: —
Origin: —

Call this capability

Human page, REST, and MCP share the same engine and calculation_version. Build verified hashes workspace artifacts only. After deploy, attest:production GETs canonical URLs twice — the public/cached view an Agent actually hits, and origin — including every /capabilities/{id} HTML page. Public Capability HTML version must match catalog before production attestation passes. Live Trust rows above fetch /.well-known/calculatorx-production-attestation.json and the output schema const. Build hashes: release integrity. That proves currently published page / engine / schema / evidence / MCP agree — not that a historical version is independently immutable. Reference Calculation Standard — Production surface contract 6/6.

curl -sS -X POST 'https://www.calculatorx.com/api/v1/calc/principal-section-modulus' \
  -H 'Content-Type: application/json' \
  -d '{"inputs":{"parts":"4,1,0,2,0,0","c1":2,"c2":1},"calculation_version":"1.0.0"}'

{
  "inputs": {
    "parts": "4,1,0,2,0,0",
    "c1": 2,
    "c2": 1
  },
  "calculation_version": "1.0.0"
}

POST /api/v1/calc/principal-section-modulus. This is a POST calculate endpoint — do not GET it.

Full REST contract: REST API docs.

Tool id: principal-section-modulus
Engine: principal-section-modulus
REST: POST /api/v1/calc/principal-section-modulus
MCP: execute_calculation with capability_id: "mechanical.statics.principal_section_modulus"
Agent input schema: Canonical (MCP / Agent)
Output schema: JSON Schema (latest)
Versioned input schema: Immutable pin (1.0.0)
Versioned output schema: Immutable pin (1.0.0)

References

Human-readable sources plus CVP reference evidence classes.

Sources

Hibbeler, Engineering Mechanics: Statics — Moments of inertia

Try with an agent

Inspect, then execute. Same engine as REST and the human calculator.

curl -sS -X POST 'https://www.calculatorx.com/mcp' \
  -H 'Content-Type: application/json' \
  -H 'MCP-Protocol-Version: 2026-07-28' \
  -H 'Mcp-Method: tools/call' \
  -H 'Mcp-Name: inspect_capability' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"inspect_capability","arguments":{"capability_id":"mechanical.statics.principal_section_modulus"},"_meta":{"io.modelcontextprotocol/protocolVersion":"2026-07-28","io.modelcontextprotocol/clientInfo":{"name":"calculatorx-docs-example","version":"1.0.0"},"io.modelcontextprotocol/clientCapabilities":{}}}}'

curl -sS -X POST 'https://www.calculatorx.com/mcp' \
  -H 'Content-Type: application/json' \
  -H 'MCP-Protocol-Version: 2026-07-28' \
  -H 'Mcp-Method: tools/call' \
  -H 'Mcp-Name: execute_calculation' \
  -d '{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"execute_calculation","arguments":{"capability_id":"mechanical.statics.principal_section_modulus","inputs":{"parts":"4,1,0,2,0,0","c1":2,"c2":1},"calculation_version":"1.0.0"},"_meta":{"io.modelcontextprotocol/protocolVersion":"2026-07-28","io.modelcontextprotocol/clientInfo":{"name":"calculatorx-docs-example","version":"1.0.0"},"io.modelcontextprotocol/clientCapabilities":{}}}}'

Pin calculation_version (1.0.0) when the result must stay reproducible.

Inspect the trust tier and required assurance level before execution. Full protocol notes: MCP docs.