Francis-99: Evaluation of the strain energy density value for welded joints typical of turbine runner blades

Pietro Foti,Filippo Berto

doi:10.1088/1742-6596/1296/1/012007

Abstract

The main aim of this work is to investigate the fatigue behaviour of welded joints through an energetic approach based on the Strain Energy Density failure criteria. The geometries, taken from the literature, are typical of turbine runner blades. The results of the fatigue tests on these details were summarised through the Strain Energy Density approach. The application of this method to these geometries is the first step of a wider research with the aim to provide a suitable tool in FEM code for the lifetime estimation of components characterised by complex geometries.

Highlights

Dealing with welded joints the design guides suggest the use of global methods [1,2,3] for the fatigue assessment even if the nature of fatigue phenomenon is local
In order to verify the feasibility of the local approaches to assess the fatigue behaviour of complex components, the present work summarises, through an energetic approach, some experimental fatigue tests from the literature carried out for the fatigue assessment of turbine runners
The results of the analysis are summarised in fig. 8, in a double logarithmic diagram, reporting the value of the averaged Strain Energy Density (SED) evaluated through the numerical analysis versus the cycles to failure taken from the experimental tests data

Summary

Introduction

Dealing with welded joints the design guides suggest the use of global methods [1,2,3] for the fatigue assessment even if the nature of fatigue phenomenon is local. Fatigue assessment of steel welded joints The high-cycle fatigue failure usually happens in the linear elastic regime and shows a brittle nature These two conditions allow the use of the SED method, in terms of the cyclic averaged SED ∆W of the pointed weld notch, dealing with welded joints made of steel or aluminium alloy under different loading conditions [20,21,22,23]. In this case, the radius of the control volume R0 can be estimated by means of the expression (5): R0 =.

FE analysis

Conclusions