Probabilistic fracture mechanics studies in the reliable design of pressure vessels

Abstract

In recent years, Probabilistic Fracture Mechanics (PFM) has becoming newlinean increasingly popular for realistic evaluation of fracture response and newlinereliability of cracked structures. The traditional approach to safety assessment newlineand design lies in a deterministic model in which safety factors are usually newlineassigned from heuristic and arbitrary decisions to handle the uncertainties. newlineUntil now, there is no straight-forward universal method to appropriately newlinedefine the safety factor. Use of the arbitrary safety factor is prone to reach newlinesolutions which are too conservative and over redundant that results in newlineadditional weight of the component and costs penalty. Hence there is need to newlinedevelop analytical methods to tackle the uncertainties systematically and newlinerationally during design. PFM provides a more rational way of describing the newlineactual behaviour and reliability of the structures than the traditional deterministic models. Using PFM, one can incorporate statistical uncertainties newlinein engineering design and evaluation. A realistic evaluation of structural newlineperformance can be achieved only if the uncertainty in structural loads, flaw newlinesizes and material properties are considered. newlineThe PFM analysis of an engineering system is concerned with newlinefinding a design such that safe operating condition is obtained while ensuring newlinethat the system reliability is within an acceptable limit. From the detailed newlineliterature review, it is found that the probabilistic failure assessment of newlineunflawed and flawed cylindrical pressure vessel containing axial through and newlinesurface cracks in the aerospace applications are scarcely reported. In this study, the probabilistic failure assessment methodology has been proposed newlineand implemented for the prediction of safe operating pressure for the newlineunflawed high strength steel pressure vessel using various failure pressure newlineprediction equations.