Simulation of Slip-Oxidation Process by Mesh Adaptivity in a Cohesive Zone Framework

Area of Science:

• Materials Science
• Nuclear Engineering
• Computational Mechanics

Background:

• Intergranular stress corrosion cracking (IGSCC) is a critical failure mechanism in boiling water reactors (BWRs).
• Accurate modeling of oxide layer behavior is essential for predicting IGSCC progression.
• Existing models may not fully capture the coupled physics of oxide growth and fracture.

Purpose of the Study:

• To develop a cohesive element-based multi-physics model that incorporates adaptive oxide thickness.
• To simulate the complex phenomena of IGSCC in BWR environments.
• To couple fracture properties with evolving oxide layers.

Main Methods:

• A multi-physics model was developed using cohesive elements.
• A slip-oxidation and diffusion model was integrated to simulate oxide behavior.
• Oxide thickness was adaptively updated within structural iterations, representing the cohesive element's physical length.
• The cyclic process of oxide film growth, rupture, and re-passivation was modeled.

Main Results:

• The model successfully simulated the cyclic physics of slip-oxidation.
• Adaptive oxide thickness was effectively coupled with cohesive element fracture properties.
• Model predictions showed good agreement with experimental data for stress intensity factor, cold work effects, and environmental factors (conductivity, corrosion potential).

Conclusions:

• The developed multi-physics model provides a robust framework for simulating IGSCC in BWRs.
• Adaptive oxide thickness is a crucial factor in accurately predicting IGSCC behavior.
• The model's validation against experimental results demonstrates its potential for engineering applications.