Dirlik Rainflow Counting Method from Response PSD

A number of methods have been derived for performing rainflow cycle counting for a response PSD. Note that they tend to be conservative.

The Dirlik method is an example of a semi-empirical method for cycle identification.

A Matlab script for performing this method is given at: Dirlik_rainflow.zip

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The following script calculates the Dirlik fatigue cycles for a single-degree-of-freedom (SDOF) system subjected to a base input PSD: sdof_ran.zip

The natural frequency and damping value for the system are required inputs.

The immediate output of the Dirlik method is a “Cumulative Histogram of Range (peak-valley).”

This can readily be converted into individual cycles with their respective amplitudes, where: amplitude=(peak-valley)/2

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The following script has a function which calculates the Dirlik fatigue damage spectrum for an array of degree-of-freedom (SDOF) systems subjected to a base input PSD.

Matlab script: Vibrationdata Signal Analysis Package

The natural frequency is an independent variable. The damping value is required. The fatigue exponent from the S-N curve slope is also required.

The calculation can be performed faster using a C++ program. Here is the source code for a C++ vibration response program which has a fatigue damage spectrum option: vrs.cpp

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Reference papers:

T. Irvine, Experimental Verification of the Dirlik Fatigue Cycle Method. Download

Halfpenny & Kim, Rainflow Cycle Counting and Acoustic Fatigue Analysis Techniques for Random Loading. Download

Halfpenny, A frequency domain approach for fatigue life estimation from Finite Element Analysis, nCode International Ltd., Sheffield UK. Download

Mrsnik, Janko Slavic, Boltezar, Frequency-domain methods for a vibration-fatigue-life estimation – Application to real data:  mrsnik_article_vib_fatigue.pdf* * *

See also:

Rainflow Fatigue Cycle Counting

Fatigue Damage Spectrum, Time Domain

Spectral Moments Notes

– Tom Irvine

4 thoughts on “Dirlik Rainflow Counting Method from Response PSD

  1. Pingback: Fatigue Damage Spectrum, Time Domain | Vibrationdata

  2. Pingback: Optimized PSD Envelope for Nonstationary Vibration | Vibrationdata

  3. Pingback: Fatigue Damage Spectrum, Frequency Domain | Vibrationdata

  4. Pingback: Rainflow Fatigue | vibrationdatapython

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