SYMPOSIA PAPER Published: 01 January 1997

Development of an Expert System for Fractography of Environmentally Assisted Cracking


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.

Author Information

Minoshima, K
Graduate School of Engineering, Kyoto University, Japan
Yamasaki, N
Advanced Technology Research Laboratory, Nippon Steel Corp., Kawasaki, Japan
Komai, K
Graduate School of Engineering, Kyoto University, Japan
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Developed by Committee: E04
Pages: 131–143
DOI: 10.1520/STP13768S
ISBN-EB: 978-0-8031-5367-7
ISBN-13: 978-0-8031-2419-6