Development of an Expert System for Fractography of Environmentally Assisted Cracking

    Published: Jan 1997

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    An expert system that diagnoses the causes of failure of environmentally assisted cracking (EAC) based upon fractography has been developed. The system uses the OPS83 programming language, expressing rules in the manner of production rules, and is composed of three independent subsystems, which respectively deal with EACs of high-strength or high-tensile-strength steel, aluminum alloy, and stainless steel in dry and humidified air, water, and aqueous solutions containing Cl, Br, or I ions. The concerned EAC issues cover stress corrosion cracking (SCC), hydrogen embrittlement, cyclic SCC, dynamic SCC, and corrosion fatigue as well as fatigue and overload fracture. The knowledge base covers the rules relating to not only environments, materials, and loading conditions, but also macroscopic and microscopic fracture surface morphology. In order to deal with vague expressions of fracture surface morphology, fuzzy set theory is used in the system, and the description of rules about vague fracture surface appearance is thereby possible. Applying the developed expert system to case histories, accurate diagnoses were made. We discuss the related diagnosis results and usefulness of the developed system.


    expert system, fractography, fracture, fatigue, stress corrosion cracking, hydrogen embrittlement, corrosion fatigue, dynamic stress corrosion cracking, cyclic stress corrosion cracking, environmentally assisted cracking, effect of environment, production system, fuzzy set theory

    Author Information:

    Minoshima, K
    Associate professor and professor, Graduate School of Engineering, Kyoto University,

    Yamasaki, N
    Research engineer, Advanced Technology Research Laboratory, Nippon Steel Corp., Kawasaki,

    Komai, K
    Associate professor and professor, Graduate School of Engineering, Kyoto University,

    Committee/Subcommittee: E04.01

    DOI: 10.1520/STP13768S

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