Basquin S-N fatigue life API

Returns cycles (and reversals) to failure from a fully-reversed alternating stress via the Basquin power law, supporting both the σf'(2N) reversal basis and the S=a·N^b cycle basis. Answers 'How many cycles until fatigue failure at this stress?', 'Am I in the high-cycle regime?'.

Price$0.06per request

MethodPOST

Route/v1/engineering/fatigue-sn-life

StatusLive

MIME typeapplication/json

Rate limit120/minute

Cache0s public

fatigues-n-curvebasquincycles-to-failurehigh-cycleendurancewohlermachine-design

API URLhttps://x402.hexl.dev/v1/engineering/fatigue-sn-life

Integration docs

Example request

{
  "alternatingStressMpa": 200,
  "fatigueStrengthCoeffMpa": 1000,
  "fatigueExponentB": -0.1
}

Example response

{
  "cyclesToFailure": 4882812.5,
  "reversalsToFailure": 9765625,
  "alternatingStressMpa": 200,
  "cycleBasis": "reversal",
  "formula": "N = 0.5·(σa/σf')^(1/b)",
  "interpretation": "Above ~1e6 cycles — high-cycle / near-infinite-life regime."
}

Input schema

{
  "type": "object",
  "required": [
    "alternatingStressMpa",
    "fatigueStrengthCoeffMpa",
    "fatigueExponentB"
  ],
  "properties": {
    "alternatingStressMpa": {
      "type": "number",
      "examples": [
        200
      ]
    },
    "fatigueStrengthCoeffMpa": {
      "type": "number",
      "description": "σf' (reversal) or a (cycle line)",
      "examples": [
        1000
      ]
    },
    "fatigueExponentB": {
      "type": "number",
      "description": "Basquin exponent b (< 0)",
      "examples": [
        -0.1
      ]
    },
    "cycleBasis": {
      "type": "string",
      "enum": [
        "reversal",
        "cycle"
      ],
      "examples": [
        "reversal"
      ]
    }
  }
}

Output schema

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