Mode I Stress Intensity Factor Solutions for Cracks Emanating from a Semi-Ellipsoidal Pit

Area of Science:

• Solid Mechanics
• Fracture Mechanics
• Computational Engineering

Background:

• Stress intensity factor (SIF) is crucial in linear elastic fracture mechanics for predicting fatigue crack growth.
• Existing literature lacks SIF solutions for cracks originating from 3D semi-ellipsoidal pits.

Purpose of the Study:

• To conduct a comprehensive parametric investigation of Mode I stress intensity factor (KI) for cracks emanating from semi-ellipsoidal pits.
• To analyze the influence of pit geometry and crack dimensions on KI.
• To develop a predictive model for KI.

Main Methods:

• Finite element analysis (FEA) simulations controlled by Python scripts.
• Calculation of KI using the displacement extrapolation method.
• Parametric study involving normalized geometric parameters: a/2c, a/t, and R/a.
• Development of a predictive model using k-d tree and k-NN algorithms based on 216 FEA simulations.

Main Results:

• Identified the significant effect of normalized geometric parameters on KI.
• Determined that the crack-radius-to-pit-depth ratio (R/a) is the dominating parameter influencing KI.
• Successfully incorporated FEA data into a predictive model.

Conclusions:

• The R/a ratio is the primary geometric factor governing KI for cracks from semi-ellipsoidal pits.
• The developed k-NN predictive model offers a valuable tool for estimating KI in such configurations.
• This research addresses a gap in SIF solutions for complex 3D pit geometries.