Extend Engineer MCP

README.md

@@ -22,6 +22,7 @@ The release covers these domains:
 - Helical compression spring design.
 - Shaft torsion and first critical speed.
 - Bearing rating life to ISO 281.
+- Interference fit analysis by Lamé thick-cylinder theory.
 - von Mises equivalent stress.
 - Cross-section properties.
 - Dimension-safe unit conversion.
@@ -52,6 +53,7 @@ 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. |
+| `press_fit` | Contact pressure, stresses, and torque 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 +149,26 @@ References:
   - Machinery's Handbook (Thirty-first edition)
 ```
 
+A call to `press_fit` for a hardened-steel hub pressed onto a solid shaft with 0.05 mm of diametral interference:
+
+```text
+Interface contact pressure                157.5 MPa
+Hub tangential stress                    262.5 MPa
+Shaft tangential stress                 -157.5 MPa
+Radial stress at interface              -157.5 MPa
+Hub von Mises stress                     367.5 MPa
+Shaft von Mises stress                   157.5 MPa
+Press-in force                           55.67 kN
+Torque capacity                          695.8 N·m
+
+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))), u = I/2, ...
+References:
+  - Shigley's Mechanical Engineering Design (Tenth edition, 2015)
+  - Machinery's Handbook (Thirty-first edition)
+  - Roark's Formulas for Stress and Strain (Eighth edition, 2011)
+```
+
 A call to `unit_convert` with a torque-to-energy request fails safely:
 
 ```text
@@ -169,7 +191,7 @@ 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.
+- 115 tests across 11 files.
 - All tests pass on Node 22 and Node 24.
 - The CI workflow runs typecheck, tests, build, demo, and a package check.
 
@@ -184,6 +206,8 @@ 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 press fit uses plane stress and assumes a uniform friction coefficient.
+  It ignores rotation, temperature, and surface roughness effects.
 - The built-in SQLite module of Node.js is still experimental.
 
 Check the cited sources for exact values.
@@ -197,11 +221,12 @@ 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.
+- Press-fit and interference-fit analysis.
+  The `press_fit` tool reports the contact pressure, the stresses, the press-in force, and the torque capacity.
 
 ### Remaining
 
 - Add fatigue analysis for cyclic loads.
-- Add press-fit and interference-fit calculators.
 - Add more unit categories, including viscosity and thermal conductivity.
 - Add HTTP transport.
 - Add a catalog of ISO and DIN standard sections.

docs/integration.md

@@ -41,11 +41,11 @@ 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.
+- Press-fit and interference-fit analysis. The `press_fit` tool computes the contact pressure, the stresses, the press-in force, and the torque capacity.
 
 ### Remaining
 
 - Add fatigue analysis for cyclic loads.
-- Add press-fit and interference-fit calculators.
 - Add more unit categories, including viscosity and thermal conductivity.
 - Add HTTP transport in addition to stdio.
 - Add a catalog of ISO and DIN standard sections.

docs/mcp-tools.md

@@ -135,6 +135,44 @@ Inputs:
 - `speedRpm`: enables life in hours.
 - `requiredLifeHours`: enables the life margin.
 
+## press_fit
+
+Compute the contact pressure and stresses of an interference fit.
+
+The tool uses the Lamé thick-cylinder solution in plane stress. The hub carries tensile hoop stress. The shaft carries compressive hoop stress. A solid shaft sees biaxial compression equal to the contact pressure.
+
+Inputs:
+
+- `hubOuterDiameter`: hub outer diameter in metres.
+- `interfaceDiameter`: diameter where the hub bore meets the shaft outside in metres.
+- `shaftInnerDiameter`: shaft inner diameter in metres. Omit or use zero for a solid shaft.
+- `hubLength`: hub engagement length in metres.
+- `diametralInterference`: total diametral interference in metres.
+- `hubMaterial` and `shaftMaterial`: material names from the database.
+- `hubElasticModulus` and `shaftElasticModulus`: elastic moduli in pascals. Use these instead of materials.
+- `hubPoissonRatio` and `shaftPoissonRatio`: Poisson ratios. The default is `0.3`.
+- `hubYieldStrength` and `shaftYieldStrength`: yield strengths in pascals. They enable the safety factors.
+- `frictionCoefficient`: friction at the interface. The default is `0.15`.
+- `appliedAxialForce`: applied axial force in newtons. It enables the axial joint safety factor.
+
+The tool reports the contact pressure, the hoop stresses, the von Mises stresses, the press-in force, and the torque capacity. The hub safety factor is the primary safety factor. The shaft and axial joint factors appear as quantities.
+
+The tool warns on a thin hub. It warns when an applied axial force exceeds the press-in force.
+
+Example:
+
+```json
+{
+  "hubOuterDiameter": 0.05,
+  "interfaceDiameter": 0.025,
+  "hubLength": 0.03,
+  "diametralInterference": 0.00005,
+  "hubMaterial": "Alloy steel 42CrMo4",
+  "shaftMaterial": "Alloy steel 42CrMo4",
+  "outputUnits": { "contactPressure": "MPa", "pressForce": "kN" }
+}
+```
+
 ## von_mises
 
 Compute the von Mises equivalent stress and yield safety factor of a stress state.

examples/demo.ts

@@ -73,6 +73,7 @@ type ToolHandlers = {
   spring_design: Handler;
   shaft_analysis: Handler;
   bearing_life: Handler;
+  press_fit: Handler;
   von_mises: Handler;
   unit_convert: Handler;
   material_lookup: Handler;
@@ -87,6 +88,7 @@ const tools: NamedHandler[] = [
   ["spring_design", toolHandlers.spring_design],
   ["shaft_analysis", toolHandlers.shaft_analysis],
   ["bearing_life", toolHandlers.bearing_life],
+  ["press_fit", toolHandlers.press_fit],
   ["von_mises", toolHandlers.von_mises],
   ["unit_convert", toolHandlers.unit_convert],
   ["unit_convert (torque to energy)", toolHandlers.unit_convert],
@@ -137,6 +139,26 @@ const inputs: Array<Record<string, unknown>> = [
     speedRpm: 1500,
     requiredLifeHours: 20000,
   },
+  {
+    hubOuterDiameter: 0.05,
+    interfaceDiameter: 0.025,
+    hubLength: 0.03,
+    diametralInterference: 0.00005,
+    hubMaterial: "Alloy steel 42CrMo4",
+    shaftMaterial: "Alloy steel 42CrMo4",
+    frictionCoefficient: 0.15,
+    appliedAxialForce: 20000,
+    outputUnits: {
+      contactPressure: "MPa",
+      hubTangentialStress: "MPa",
+      shaftTangentialStress: "MPa",
+      radialStress: "MPa",
+      hubVonMisesStress: "MPa",
+      shaftVonMisesStress: "MPa",
+      pressForce: "kN",
+      torqueCapacity: "N·m",
+    },
+  },
   {
     mode: "cartesian",
     sigmaX: 120e6,

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",