July 2024 | The performance and reliability of machines and devices deteriorate as they age. Currently, inaccurate degradation characterization leads to both over- and under-maintenance, resulting in significant consequences. Therefore, there is a need for improved methods to optimize system maintenance, prevent failures, and reduce costs.
After almost a decade of investigating the physics of degradation in diverse systems such as frictional interfaces, lubricants, batteries, and metallic structures, Dr. Jude Osara, Assistant Professor in the Faculty of Engineering Technology, and Prof. Michael Bryant (retired) of the University of Texas at Austin have proposed a universal thermodynamics-based damage characterization methodology.
This approach is detailed in a two-part treatise recently published and featured in the journal Entropy: “Methods to Calculate Entropy Generation” and “Systems and Methods for Transformation and Degradation Analysis.”
Understanding System Degradation
All systems degrade over time. Without active maintenance, engineering systems eventually fail, sometimes catastrophically, particularly in sectors like transportation and construction. Preventive maintenance, which costs billions of euros annually, is essential to mitigate these failures. Accurate degradation characterization is crucial to reduce maintenance costs and prevent failures.
Starting from first principles, Jude Osara and Michael Bryant developed an approach based on the second law of thermodynamics, articulated as the Phenomenological Entropy Generation (PEG) theorem. This theorem defines a zero-aging path—representing the limit of mere existence—as a reference, and an aging path along which all real systems evolve during operation. Coupled with the Degradation-Entropy Generation (DEG) theorem, this approach directly correlates a user-selected performance indicator (any measurable system parameter) with the physics of the active process mechanisms.
Figure 1. Illustration of the Phenomenological Entropy Generation (PEG) theorem, showing the ideal zero-aging path (green line) and the aging path (purple curve). Aging/degradation (orange curve) is the vertical difference between the paths (indicated by black arrows).
Advancements in Degradation Analysis
“Prolonging the useful life of a system via in situ optimization and scheduled maintenance starts with degradation characterization. While artificial intelligence continues to gain ground in many aspects of human life, its capabilities in characterizing system degradation and instability remain grossly inadequate and prohibitively expensive. Here, we demonstrate a simple and universal method for analyzing everyday real-world systems undergoing unsteady and nonlinear interactions.” says Dr. Jude Osara.
“The PEG theorem is instantaneous and universal, and the analysis algorithm is simple, non-intrusive and inexpensive. If you can measure or estimate temperature and other process parameters such as force, velocity, stress, strain, voltage, current, etc., you are well on your way to evaluating entropy generation for your system. If you can measure or estimate material properties, entropy generation will be yours to do with as you wish. Our approach also characterizes instability and critical phenomena, demonstrated via thermal runaway in lithium-ion batteries.”
Applications and Recommendations
This physics-based methodology, which can be integrated with existing approaches, is recommended for researchers, engineers, and scientists for quantifying realistic temporal changes in their systems. By applying this method, it is possible to achieve a more accurate and cost-effective maintenance strategy, ultimately extending the lifespan and reliability of critical engineering systems.
More Information
Both articles are open access:
Osara, J.A.; Bryant, M.D. (2024) Systems and Methods for Transformation and Degradation Analysis. Entropy 2024, 26, 454. doi.org/10.3390/e26060454
Osara, J.A.; Bryant, M.D. (2024) Methods to Calculate Entropy Generation. In: Entropy 2024, 26, 237. doi.org/10.3390/e26030237
