Extend Engineer MCP

.github/workflows/ci.yml

@@ -36,6 +36,12 @@ jobs:
       - name: Build
         run: npm run build
 
+      - name: Verify the CLI contract
+        run: |
+          node dist/index.js --version | grep -q "^engineer-mcp"
+          node dist/index.js --list | grep -q "beam_bending"
+          node dist/index.js --list | grep -q "press_fit"
+
       - name: Verify the demo runs
         run: npm run demo
 

README.md

@@ -22,9 +22,11 @@ The release covers these domains:
 - Helical compression spring design.
 - Shaft torsion and first critical speed.
 - Bearing rating life to ISO 281.
+- Fatigue life to the Soderberg, Goodman, Gerber, and ASME-elliptic criteria.
+- Press-fit and interference-fit joint design by Lamé theory.
 - von Mises equivalent stress.
 - Cross-section properties.
-- Dimension-safe unit conversion.
+- Dimension-safe unit conversion, including viscosity and thermal conductivity.
 - Material property lookup.
 
 ## How results stay trustworthy
@@ -52,6 +54,8 @@ Warnings surface when a method uses an approximation.
 | `spring_design` | Spring rate, shear stress, and safety factor of a compression spring. |
 | `shaft_analysis` | Torsion stress, twist, and critical speed. |
 | `bearing_life` | ISO 281 rating life in revolutions and hours. |
+| `fatigue_analysis` | Fatigue safety factors for a constant-amplitude stress cycle. |
+| `press_fit` | Contact pressure, stresses, and capacity of an interference fit. |
 | `von_mises` | Equivalent stress and yield safety factor. |
 | `unit_convert` | Conversion between compatible units. |
 | `material_lookup` | Curated mechanical properties of materials. |
@@ -147,6 +151,43 @@ References:
   - Machinery's Handbook (Thirty-first edition)
 ```
 
+A call to `fatigue_analysis` for a steel part under a fluctuating load:
+
+```text
+Endurance limit                         310 MPa
+Mean stress                             100 MPa
+Alternating stress                      100 MPa
+Soderberg fatigue factor              1.622
+Modified Goodman fatigue factor          2.067
+Gerber fatigue factor                 2.568
+ASME-elliptic fatigue factor          2.291
+First-cycle yield factor                1.7
+Governing fatigue factor              1.622
+
+Method: Constant-amplitude fatigue criteria
+Formula: Soderberg: Sa/Se + Sm/Sy = 1/n. Goodman: Sa/Se + Sm/Sut = 1/n
+References:
+  - Shigley's Mechanical Engineering Design (Tenth edition, 2015)
+```
+
+A call to `press_fit` for a steel hub on a steel shaft with 20 µm interference:
+
+```text
+Interface contact pressure             52.5 MPa
+Hub tangential stress                  87.5 MPa
+Shaft tangential stress               -52.5 MPa
+Hub von Mises stress                  122.5 MPa
+Press-in force                        22.27 kN
+Torque capacity                         334 N·m
+Hub safety factor                     2.898
+
+Method: Interference fit by Lamé thick-cylinder theory
+Formula: p = u / (r ((1/Eh)((ro^2+r^2)/(ro^2-r^2)+nh) + (1/Es)((r^2+ri^2)/(r^2-ri^2)-ns)))
+References:
+  - Shigley's Mechanical Engineering Design (Tenth edition, 2015)
+  - Machinery's Handbook (Thirty-first edition)
+```
+
 A call to `unit_convert` with a torque-to-energy request fails safely:
 
 ```text
@@ -169,9 +210,9 @@ Use a unit of the same quantity.
 The test suite is deterministic and offline.
 It covers the engines, the unit layer, the database, and the tools.
 
-- 98 tests across 10 files.
+- 135 tests across 12 files.
 - All tests pass on Node 22 and Node 24.
-- The CI workflow runs typecheck, tests, build, demo, and a package check.
+- The CI workflow runs typecheck, tests, build, the CLI contract, the demo, and a package check.
 
 Run `npm test` to reproduce the results.
 
@@ -184,6 +225,10 @@ Run `npm test` to reproduce the results.
 - The critical speed is a first-mode approximation.
 - The spring design covers static round-wire springs only.
   It does not estimate fatigue life for cyclic loads.
+- The fatigue criteria assume a polished test specimen.
+  Apply surface, size, and loading factors to a real part.
+- The press-fit theory assumes uniform contact along the hub.
+  It ignores stress concentrations at the hub edges.
 - The built-in SQLite module of Node.js is still experimental.
 
 Check the cited sources for exact values.
@@ -197,12 +242,18 @@ Each release stays useful on its own.
 
 - Helical compression spring design.
   The `spring_design` tool reports the spring rate, the shear stress, and the safety factor.
+- Constant-amplitude fatigue analysis.
+  The `fatigue_analysis` tool reports factors for four fatigue criteria.
+- Press-fit and interference-fit design.
+  The `press_fit` tool reports pressure, stresses, and joint capacity.
+- Viscosity and thermal-conductivity units.
+  The `unit_convert` tool converts dynamic viscosity, kinematic viscosity, and thermal conductivity.
 
 ### Remaining
 
-- Add fatigue analysis for cyclic loads.
-- Add press-fit and interference-fit calculators.
-- Add more unit categories, including viscosity and thermal conductivity.
+- Add fatigue analysis for welded or notched joints.
+- Add a shrink-fit temperature for assembly.
+- Add more unit categories, including specific heat capacity.
 - Add HTTP transport.
 - Add a catalog of ISO and DIN standard sections.
 

docs/integration.md

@@ -41,12 +41,15 @@ Engineer MCP grows in independent releases. Each release stays useful on its own
 ### Complete
 
 - Helical compression spring design. The `spring_design` tool computes the spring rate, the shear stress, and the safety factor.
+- Constant-amplitude fatigue analysis. The `fatigue_analysis` tool reports factors for the Soderberg, Goodman, Gerber, and ASME-elliptic criteria.
+- Press-fit and interference-fit design. The `press_fit` tool reports pressure, stresses, and joint capacity from Lamé theory.
+- Viscosity and thermal-conductivity units. The `unit_convert` tool covers dynamic viscosity, kinematic viscosity, and thermal conductivity.
 
 ### Remaining
 
-- Add fatigue analysis for cyclic loads.
-- Add press-fit and interference-fit calculators.
-- Add more unit categories, including viscosity and thermal conductivity.
+- Add fatigue analysis for welded or notched joints.
+- Add a shrink-fit temperature for assembly.
+- Add more unit categories, including specific heat capacity.
 - Add HTTP transport in addition to stdio.
 - Add a catalog of ISO and DIN standard sections.
 

docs/mcp-tools.md

@@ -135,6 +135,59 @@ Inputs:
 - `speedRpm`: enables life in hours.
 - `requiredLifeHours`: enables the life margin.
 
+## fatigue_analysis
+
+Compute fatigue safety factors for a constant-amplitude stress cycle.
+
+The tool evaluates the Soderberg, modified Goodman, Gerber, and ASME-elliptic criteria. It reports the minimum factor as the governing factor.
+
+Inputs:
+
+- `meanStress`: mean stress in pascals. Negative values are compressive.
+- `amplitudeStress`: alternating stress in pascals. Zero means a steady load.
+- `ultimateStrength`: ultimate tensile strength in pascals.
+- `yieldStrength`: yield strength in pascals. Enables the Soderberg and ASME-elliptic criteria.
+- `enduranceLimit`: endurance limit in pascals. The tool estimates it when missing.
+- `criterion`: one of `soderberg`, `goodman`, `gerber`, `asme_elliptic`, or `all`. The default is `all`.
+
+The tool warns when the mean stress is compressive. It warns when the endurance limit is an estimate. It warns when the governing factor is below one.
+
+## press_fit
+
+Compute the contact pressure, stresses, and capacity of an interference fit.
+
+The tool uses the Lamé solution for two cylinders in interference. The hub carries tensile hoop stress. The shaft carries compressive hoop stress.
+
+Inputs:
+
+- `hubOuterDiameter`: hub outer diameter in metres.
+- `interfaceDiameter`: interface diameter in metres.
+- `shaftInnerDiameter`: shaft inner diameter in metres. The default is a solid shaft.
+- `hubLength`: hub engagement length in metres.
+- `diametralInterference`: diametral interference in metres.
+- `hubElasticModulus` and `shaftElasticModulus`: Young's moduli in pascals.
+- `hubPoissonRatio` and `shaftPoissonRatio`: Poisson's ratios. The default is `0.3`.
+- `frictionCoefficient`: interface friction coefficient. The default is `0.15` for dry steel.
+- `hubYieldStrength`: enables the hub safety factor.
+- `shaftYieldStrength`: enables the shaft safety factor.
+- `appliedAxialForce`: enables the axial joint safety factor.
+
+Example:
+
+```json
+{
+  "hubOuterDiameter": 0.06,
+  "interfaceDiameter": 0.03,
+  "hubLength": 0.03,
+  "diametralInterference": 0.00002,
+  "hubElasticModulus": 210000000000,
+  "shaftElasticModulus": 210000000000,
+  "hubYieldStrength": 355000000
+}
+```
+
+The tool warns on a thin hub. It warns when the applied axial force exceeds the press-in force.
+
 ## von_mises
 
 Compute the von Mises equivalent stress and yield safety factor of a stress state.
@@ -156,6 +209,14 @@ Inputs:
 - `from`: source unit symbol.
 - `to`: target unit symbol.
 
+The converter covers these quantities:
+
+- length, mass, time, and angle.
+- temperature, force, pressure, and torque.
+- energy, power, velocity, and acceleration.
+- area, volume, density, and stiffness.
+- frequency, dynamic viscosity, kinematic viscosity, and thermal conductivity.
+
 The converter rejects mismatched dimensions and mismatched quantity categories. For example, it rejects a torque-to-energy conversion.
 
 ## material_lookup

examples/demo.ts

@@ -76,6 +76,8 @@ type ToolHandlers = {
   von_mises: Handler;
   unit_convert: Handler;
   material_lookup: Handler;
+  fatigue_analysis: Handler;
+  press_fit: Handler;
 };
 
 const toolHandlers = handlers as ToolHandlers;
@@ -90,6 +92,9 @@ const tools: NamedHandler[] = [
   ["von_mises", toolHandlers.von_mises],
   ["unit_convert", toolHandlers.unit_convert],
   ["unit_convert (torque to energy)", toolHandlers.unit_convert],
+  ["unit_convert (thermal conductivity)", toolHandlers.unit_convert],
+  ["fatigue_analysis", toolHandlers.fatigue_analysis],
+  ["press_fit", toolHandlers.press_fit],
   ["material_lookup", toolHandlers.material_lookup],
 ];
 
@@ -155,6 +160,39 @@ const inputs: Array<Record<string, unknown>> = [
     from: "N·m",
     to: "J",
   },
+  {
+    value: 205,
+    from: "W/(m·K)",
+    to: "BTU/(ft·h·degF)",
+  },
+  {
+    meanStress: 100e6,
+    amplitudeStress: 100e6,
+    ultimateStrength: 620e6,
+    yieldStrength: 340e6,
+    outputUnits: { enduranceLimit: "MPa", meanStress: "MPa", amplitudeStress: "MPa" },
+  },
+  {
+    hubOuterDiameter: 0.06,
+    interfaceDiameter: 0.03,
+    hubLength: 0.03,
+    diametralInterference: 20e-6,
+    hubElasticModulus: 210e9,
+    shaftElasticModulus: 210e9,
+    hubYieldStrength: 355e6,
+    shaftYieldStrength: 355e6,
+    appliedAxialForce: 10000,
+    outputUnits: {
+      contactPressure: "MPa",
+      hubTangentialStress: "MPa",
+      shaftTangentialStress: "MPa",
+      radialStress: "MPa",
+      hubVonMisesStress: "MPa",
+      shaftVonMisesStress: "MPa",
+      pressForce: "kN",
+      torqueCapacity: "N·m",
+    },
+  },
   {
     query: "steel",
   },

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@engineerkit/engineer-mcp",
-  "version": "0.2.0",
+  "version": "0.3.0",
   "description": "MCP server for verified mechanical-engineering calculations, references, and material data.",
   "type": "module",
   "license": "MIT",
@@ -48,6 +48,8 @@
     "engineering",
     "calculations",
     "unit-conversion",
+    "fatigue",
+    "press-fit",
     "sqlite",
     "provenance",
     "engineerkit"