The Mesh-Insensitive Structural Stress Method: Current State and Prospects for Additively Manufactured Components

Abstract Fatigue failure in welded structures is strongly influenced by stress concentration, which in turn depends on plate thickness, loading mode, weld geometry, among others. Traditional fatigue assessment approaches, such as nominal stress, hot-spot stress, and effective notch stress methods, have been applied in design codes and engineering practice, but they can become difficult to apply consistently to complex welded structures. One major issue is how to suppress mesh-size sensitivity in finite element models. The mesh-insensitive structural stress method has been shown as an effective alternative method since its adoption by the ASME Boiler and Pressure Vessel Code since 2007. The method leads to the master S–N curve approach, which correlates fatigue data from a wide range of welded joint types using a unified fatigue curve and scatter band. This paper reviews the mechanics foundation, finite-element implementation, current engineering applications, advantages, limitations, and on-going development in the area of low cycle fatigue, and applications for fatigue evaluation of additively manufactured metal components.