Stress-concentration factor Kt API

Returns the theoretical stress-concentration factor Kt and peak stress for a circular hole (infinite or finite-width plate, Heywood) or a shoulder fillet. Answers 'How much does this hole/fillet amplify my nominal stress?', 'What is the peak local stress?'.

Price$0.06per request

MethodPOST

Route/v1/engineering/stress-concentration

StatusLive

MIME typeapplication/json

Rate limit120/minute

Cache0s public

materialstress-concentrationktnotchholefilletpeak-stressmachine-design

API URLhttps://x402.hexl.dev/v1/engineering/stress-concentration

Integration docs

Example request

{
  "feature": "hole-finite-width",
  "nominalStressMpa": 50,
  "holeDiameterMm": 10,
  "plateWidthMm": 50
}

Example response

{
  "stressConcentrationFactorKt": 2.5065,
  "nominalStressMpa": 50,
  "peakStressMpa": 125.3232,
  "feature": "hole-finite-width",
  "detail": "Kt = 3 − 3.14(d/W) + 3.667(d/W)² − 1.527(d/W)³ (Heywood, gross-area nom)",
  "interpretation": "Peak stress = Kt·σnom drives crack initiation; sharper radii (small r/d) raise Kt steeply."
}

Input schema

{
  "type": "object",
  "required": [
    "nominalStressMpa"
  ],
  "properties": {
    "feature": {
      "type": "string",
      "enum": [
        "hole-infinite",
        "hole-finite-width",
        "shoulder-fillet"
      ],
      "examples": [
        "hole-finite-width"
      ]
    },
    "nominalStressMpa": {
      "type": "number",
      "examples": [
        50
      ]
    },
    "holeDiameterMm": {
      "type": "number",
      "examples": [
        10
      ]
    },
    "plateWidthMm": {
      "type": "number",
      "examples": [
        50
      ]
    },
    "largerWidthMm": {
      "type": "number",
      "examples": [
        60
      ]
    },
    "smallerWidthMm": {
      "type": "number",
      "examples": [
        40
      ]
    },
    "filletRadiusMm": {
      "type": "number",
      "examples": [
        5
      ]
    }
  }
}

Output schema

{
  "type": "object",
  "additionalProperties": true
}