Managing Our Aging Physical Systems: A Corrosion Perspective

Modern society relies heavily on complex, intertwined, physical infrastructures for their smooth functioning. Aging of the materials in the physical infrastructures is not necessarily related to service life, but to the increasing probability of failure-the hazard rate. This paper provides a holistic perspective of the hazard rates of conventional, metallic materials. Data -based approaches to estimating the hazard rate overlong periods are constrained by available data and the assumption that failure modes remain unchanged. Aging structures may suffer from failure modes that change with time and some that are unanticipated-the problem of unknown unknowns. Mechanistic understanding of failure modes is essential to predicting hazard rates of aging systems. Researchers on the aging of biological systems have enumerated 12 hallmarks of biological aging. However, unlike the biological community, the engineering community has not systematically tackled the hallmarks of aging, although much is known about aging of materials. This perspective explores the opportunities for systematizing our understanding of aging physical systems and develops a framework for their interconnections. An approach is proposed to tackle the problem of the unknown unknowns.