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Engineering · Stress, Failure & Materials

Notch Sensitivity and Fatigue Factor Calculator

Relate an entered theoretical concentration factor to fatigue concentration using an entered Peterson material length and notch radius.

Engineering · Stress, Failure & Materials

Enter the engineering model

Explicit properties, geometry, units and assumptions
  1. 1EnterProvide the known values
  2. 2CalculateResults update automatically
  3. 3VerifyReview the details and units
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Visual modelSchematic · not to scale
Stress, Failure & Materials: peterson visual explanationA simplified diagram showing the relationship represented by the selected calculator mode. It is explanatory and not a fabrication, safety or scale drawing.notch radius r and entered material length aKt → q → fatigue concentration Kf
The diagram explains the selected relationship only. Dimensions, symbols and proportions are illustrative; use the entered values and stated assumptions for the calculation.

Keep every unit basis, sign convention, property source and idealization consistent. Values stay in this browser.

Engineering calculation result

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Understand the model

What this calculator is for

A geometric stress concentration Kt does not always transfer fully into fatigue behavior. The entered Peterson relation expresses that sensitivity through q and produces Kf.

1Source Kt for the actual geometry.
2Enter a and r in the same units.
3Use Kf only within the evidence and loading mode supporting the entered material parameter.

Visual explanation

As notch radius becomes large compared with the entered material length, q approaches one and Kf approaches Kt. A sharper notch lowers this particular q relation.

The governing relationship

Peterson form q=1/(1+a/r), then Kf=1+q(Kt−1). The entered material length a and radius r must use the same units.

Keep the boundary visible

The calculator supplies no material constant, chart, endurance limit or fatigue-life prediction. The Peterson parameter must come from applicable evidence for the material, condition and loading mode.

Quick guide

How to use this calculator

  1. Choose the analysis mode that matches the physical model before entering values.
  2. Enter properties, geometry, loads, states and coefficients from one consistent unit and sign convention.
  3. Use the intermediate outputs to audit the relationship, then retain the stated idealization before applying it.

Calculation method

Transparent engineering model

Peterson form q=1/(1+a/r), then Kf=1+q(Kt−1). The entered material length a and radius r must use the same units.

The calculator evaluates only the declared relationship and preserves visitor-entered assumptions rather than selecting materials, factors, components or standards.

Worked example

Worked example

Kt=2.5, a=0.5 mm and r=2 mm give q=0.8 and Kf=2.2.

Peterson form q=1/(1+a/r), then Kf=1+q(Kt−1). The entered material length a and radius r must use the same units.

Supported inputs

Precision and limits

Analysis, not approval

The calculator supplies no material constant, chart, endurance limit or fatigue-life prediction. The Peterson parameter must come from applicable evidence for the material, condition and loading mode.

Standards and properties

Material properties, allowable values, load combinations, safety factors, correlations, manufacturer data, codes and jurisdictional requirements are not supplied automatically.

Units and precision

Use one consistent unit basis. Results retain working precision but cannot be more accurate than the entered measurements and properties.

Privacy

Entered engineering values and results stay in this browser and are not sent to analytics or third parties.