PSI - Issue 37

Fekete, Tamás et al. / Procedia Structural Integrity 37 (2022) 779–787 Fekete, T.: The Fundaments of Structural Integrity … / Structural Integrity Procedia 00 (2021) 000 – 000

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3. Towards a Generalized Conceptual Framework to Structural Integrity of Large-Scale Pressure Systems The standards-based methodology of DSCs and SICs discussed so far known to bear the footprints of phenomenological physics developed in the second half of the 19 th century: e.g., the near exclusive use of isotropic, homogeneous, linear, and time-independent constitutive models – see Maugin (2009) – . Given these facts, it is not surprising that description of ageing of structural materials is based almost entirely on empirical evidence and correlations. Therefore, a deeper conceptual foundation for SI is needed. To this point, methodological issues of SICs have been discussed, and some reflections on the methodology have been summarised. It was found that, although SICs can nowadays be applied as effective tool in safety analyses of LSPSs , the methodology has been compiled from theoretical models based on partly incompatible assumptions and even worldviews, which can be traced back to the historical development of related disciplines in physics and engineering. This implies that when developing a Generalized Concept to SI of LSPSs , it is both appropriate and well timed to pay particular attention to its metaphysical/philosophical foundations, so that finally the Conceptual System will form a plausible and coherent system based on our best knowledge. Before moving on to the new conceptual framework, it is worth reviewing the context in which Structural Integrity is used, the concept it expresses, and the fields to which the concept is closely or more closely related. A distinction is made between the two cases, whether one is talking about the SI of a given LSPS or that of LSPSs . • Structural Integrity for an in-service LSPS is to achieve a more realistic assessment for the margin between its safe operation and failure, using SICs and appropriate practical methods to verify them (e.g., a system of dedicated measurements and other experiment-based monitoring programmes). • Structural Integrity of LSPSs means continued maintenance and improvement of the methodological framework ensuring the safe operation of such systems, addressing, and developing science and technology to evaluate the margin between safe operation and failure. SI assessments of a given LSPS means solving a practical problem using an engineering methodology, where the actual needs of industry are served by engineering. When referring to SI of LSPSs , this means R&D activities with a scientific emphasis, aimed at supporting the engineering activities that will serve the industry in the future, including occasionally clarifying fundamental methodological issues. This means developing an engineering methodology with scientific methods to serve the practical needs of future industry , where philosophical considerations could play a major role in clarifying fundamental issues. Philosophical considerations serve primarily as a vehicle for reflections, to identify postulates, hypotheses, on which the scientific investigations of the topic can be based, so providing a basis for a theory. Philosophy could be the bedrock upon which a theory/methodology is built. The concept of SI for LSPSs is a hierarchically organized multi-layered concept that covers the philosophical, scientific, engineering, and industrial areas/aspects of the subject such that these four fields together form a holistic system. The structure of the concept follows the conceptual structure proposed in Rousseau (2017) for Systemology; the conceptual framework of SI for LSPSs with this structure is referred to as the Generalised Conceptual Framework to Structural Integrity for LSPSs , whose architecture is shown on Fig. 1. At Philosophical Level , the fundamental questions, postulates, and hypotheses are concerned. Scientific Level addresses the issues addressed by theoretical and empirical methods of science. Engineering level represents the level of engineering design and other engineering problems. Industrial Level refers to the level of day-to-day industrial practice. As mentioned above, the framework is organized hierarchically; the hierarchy level of layers decreases from left to right. The arrows pointing to the right indicate that knowledge acquired at a higher level constrains thinking and activities at a lower level, while the arrows pointing to the left indicate reflection: a reflective evaluation of a lower-level knowledge/activity at a higher level provides important information on whether or not the knowledge accumulated at higher level needs to be reassessed with respect to the lessons learned at the lower level – Rousseau (2017) – . 3.1. On the Generalized Conceptual Framework to Structural Integrity