Development of Phase-field Modeling for Fatigue/Stress Corrosion Crack Growth and Additive Manufacturing
Abstract
The purpose of this research project is to develop computational modeling methods that areable to describe the propagation and interaction of boundaries using the phase-field methodologywithin the numerical framework of isogeometric analysis (IGA). The physical system that will bestudied include cracks driven by cyclic loading and corrosion. The modeling approach will bedivided into two primary thrusts, (i) phenomenological modeling of crack propagation andinteractions that reproduce the crack growth rates, in terms of time or number of cycles, as afunction of the applied stress intensity factors, and (ii) microscopic modeling of theelectrochemical processes that lead to corrosion pitting and ultimately crack nucleation andgrowth from these damage sites. The output of the research on the phenomenologicalmacroscopic modeling of fatigue/corrosion crack growth will include methods that are capable ofmodeling complex crack interactions and pattern evolution including stress shielding, cracknucleation, and intersection under stress-corrosion environments and cyclic mechanical, thermal,and possibly other types of loading (electrical, magnetic, etc.). The method will be able toincorporate inhomogeneities in the thermal, mechanical, and fracture properties of the material.The modeling technique is a phase-field method based on finite elements and IGA discretizationsthat can capture crack patterns that are significantly more complex than approaches that trackindividual crack fronts and fracture surfaces. Crack pattern features such as nucleation,branching, and the intersection of multiple cracks in three dimensions are naturally captured bythe phase-field method. This modeling strategy is an ideal tool for the study of the evolution ofcrack patterns that can emerge during fatigue crack growth. The research on microscopicmodeling of the corrosion process will utilize the features of IGA that readily allow for thesolution of higher order partial differential equations (3rd or 4th order and higher). This attributeof IGA will allow for the use of Cahn-Hilliard-type fourth order partial differential equations todescribe the diffusion of metal ions that occurs during the corrosion process. The metal ionconcentration will have a diffuse but rapid transition zone from inside the intact metal to theoutside in the corrosive environment. The chemical potential driving changes in theconcentration will depend on the local stress state, which in turn will affect the kinetics of thecorrosion pitting processes and the nucleation of stress corrosion cracks. The theory andnumerical models developed within this program will be used as a platform to analyze a widerange of stress corrosion cracking problems and may potentially be extended to other physicalprocesses like hydrogen embrittlement.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 04, 2017
- Source ID
- N000141712039
Entities
People
- Chad M. Landis
Organizations
- Office of Naval Research
- United States Navy
- University of Texas at Austin