Interacting Effects Induced by Two Neighboring Pits Considering Relative Position Parameters and Pit Depth

Area of Science:

• Materials Science
• Mechanical Engineering
• Corrosion Science

Background:

• Stress concentration around corrosion pits significantly impacts fatigue life in aluminum alloys.
• Understanding the interaction between multiple pits is critical for accurate structural integrity assessment.
• Aluminum alloy 7075-T6 is widely used in aerospace, making its corrosion behavior a key concern.

Purpose of the Study:

• To investigate the interacting effects of two neighboring pits on stress concentration in pre-corroded aluminum alloy 7075-T6.
• To determine critical corrosion regions susceptible to fatigue damage.
• To propose a method for estimating the combined stress concentration factor.

Main Methods:

• Finite element method (FEM) simulations were employed.
• Analysis considered varying relative pit positions (inclination angle θ, dimensionless spacing λ) and pit depth (d).
• Normalized stress concentration factor (Ktnor) was calculated and analyzed against geometric parameters.

Main Results:

• For intersecting pits, Ktnor increases with θ and λ, peaking at θ = 90°.
• For adjacent pits, Ktnor decreases with increasing λ, with maximums at slight asymmetry.
• Ktnor exhibits linear and exponential relationships with dimensionless pit depth (Rd) for intersecting and adjacent pits, respectively.

Conclusions:

• A straightforward approach for estimating combined stress concentration factors from neighboring pits was developed.
• The findings provide insights into fatigue susceptibility based on pit geometry and interaction.
• The study highlights the importance of considering pit proximity and depth in structural design and maintenance.