FFPACK - Fatigue and Fracture PACKage

Purpose

FFPACK ( Fatigue and Fracture PACKage ) is an open-source Python library for fatigue and fracture analysis. It supports ASTM cycle counting, load sequence generation, fatigue damage evaluation, etc. A lot of features are under active development. FFPACK is designed to help engineers analyze fatigue and fracture behavior in engineering practice.

Installation

FFPACK can be installed via PyPI:

pip install ffpack

Usage

The following example shows the usage of ASTM rainflow counting,

# Import the ASTM rainflow counting function
from ffpack.lcc import astmRainflowCounting

# Prepare the data
data = [ -2.0, 1.0, -3.0, 5.0, -1.0, 3.0, -4.0, 4.0, -2.0 ]

# Get counting results
results = astmRainflowCounting( data )

See the package document for more details and examples.

Status

FFPACK is currently under active development.

Contents

• Fatigue damage model

  • Palmgren-miner damage model
    • Naive Palmgren-miner damage model
    • Classic Palmgren-miner damage model

• Load counting and correction

  • ASTM counting
    • ASTM level crossing counting
    • ASTM peak counting
    • ASTM simple range counting
    • ASTM range pair counting
    • ASTM rainflow counting
    • ASTM rainflow counting for repeating history
  • Johannesson counting
    • Johannesson min max counting
  • Rychlik counting
    • Rychlik rainflow counting
  • Four point counting
    • Four point rainflow counting
  • Mean stress correction
    • Goodman correction
    • Soderberg correction
    • Gerber correction

• Load sequence generator

  • Random walk
    • Uniform random walk
  • Autoregressive moving average model
    • Normal autoregressive (AR) model
    • Normal moving average (MA) model
    • Normal ARMA model
    • Normal ARIMA model
  • Sequence from spectrum
    • Spectral representation

• Load spectra and matrices

  • Cycle counting matrix
    • ASTM simple range counting matrix
    • ASTM range pair counting matrix
    • ASTM rainflow counting matrix
    • ASTM rainflow counting matrix for repeating history
    • Johannesson min max counting matrix
    • Rychlik rainflow counting matrix
    • Four point rainflow counting matrix
  • Wave spectra
    • Jonswap spectrum
    • Pierson Moskowitz spectrum
    • ISSC spectrum
    • Gaussian Swell spectrum
    • Ochi-Hubble spectrum
  • Wind spectra
    • Davenport spectrum with drag coefficient
    • Davenport spectrum with roughness length
    • EC1 spectrum
    • IEC spectrum
    • API spectrum
  • Sequence spectra
    • Periodogram spectrum
    • Welch spectrum

• Random and probabilistic model

  • Metropolis-Hastings algorithm
    • Metropolis-Hastings sampler
    • Au modified Metropolis-Hastings sampler
  • Nataf algorithm
    • Nataf transformation

• Risk and reliability model

  • First order second moment
    • Mean value FOSM
  • First order reliability method
    • Hasofer-Lind-Rackwitz-Fiessler FORM
    • Constrained optimization FORM
  • Second order reliability method
    • Breitung SORM
    • Tvedt SORM
    • Hohenbichler and Rackwitz SORM
  • Simulation based reliability method
    • Subset simulation

• Utility

  • Aggregation
    • Cycle counting aggregation
  • Counting matrix
    • Counting results to counting matrix
  • Derivatives
    • Derivative
    • Central derivative weights
    • Gradient
    • Hessian matrix
  • Digitization
    • Sequence digitization
  • Fitter
    • SN curve fitter
  • Sequence filter
    • Sequence peakValley filter
    • Sequence hysteresis filter

Document

You can find the latest documentation for setting up FFPACK at the Read the Docs site.

Credits

This project was made possible by the help from DM2L lab.

License

GPLv3