Analysis of stress intensity factor for fatigue crack using bootstrap S-version finite element model

Muhamad Husnain Mohd Noh, Mohd Akramin Mohd Romlay, Chuan Zun Liang, Mohd Shamil Shaari, Akiyuki Takahashi

Research output: Contribution to journalArticle


Purpose: Failure of the materials occurs once the stress intensity factor (SIF) overtakes the material fracture toughness. At this level, the crack will grow rapidly resulting in unstable crack growth until a complete fracture happens. The SIF calculation of the materials can be conducted by experimental, theoretical and numerical techniques. Prediction of SIF is crucial to ensure safety life from the material failure. The aim of the simulation study is to evaluate the accuracy of SIF prediction using finite element analysis. Design/methodology/approach: The bootstrap resampling method is employed in S-version finite element model (S-FEM) to generate the random variables in this simulation analysis. The SIF analysis studies are promoted by bootstrap S-version Finite Element Model (BootstrapS-FEM). Virtual crack closure-integral method (VCCM) is an important concept to compute the energy release rate and SIF. The semielliptical crack shape is applied with different crack shape aspect ratio in this simulation analysis. The BootstrapS-FEM produces the prediction of SIFs for tension model. Findings: The mean of BootstrapS-FEM is calculated from 100 samples by the resampling method. The bounds are computed based on the lower and upper bounds of the hundred samples of BootstrapS-FEM. The prediction of SIFs is validated with Newman–Raju solution and deterministic S-FEM within 95 percent confidence bounds. All possible values of SIF estimation by BootstrapS-FEM are plotted in a graph. The mean of the BootstrapS-FEM is referred to as point estimation. The Newman–Raju solution and deterministic S-FEM values are within the 95 percent confidence bounds. Thus, the BootstrapS-FEM is considered valid for the prediction with less than 6 percent of percentage error. Originality/value: The bootstrap resampling method is employed in S-FEM to generate the random variables in this simulation analysis.

Original languageEnglish
JournalInternational Journal of Structural Integrity
Publication statusAccepted/In press - 1 Jan 2020



  • Bootstrap resampling method
  • Bounds
  • Random variables
  • S-version finite element model
  • Stress intensity factor

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