PSI - Issue 28

Vinicius Carrillo Beber et al. / Procedia Structural Integrity 28 (2020) 1950–1962 V.C. Beber and M. Brede / Structural Integrity Procedia 00 (2019) 000–000

1961

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Figure 13 - Representative fracture surface images of the elastic adhesive joints

4. Conclusion In the present work the multiaxial behaviour of an elastic (polyurethane-based) and a structural adhesive (epoxy based) for railway applications was investigated. Butt, scarf, and thick adherend shear test joints were tested under static and fatigue conditions. The stress multiaxiality was defined in terms of the ratio between the hydrostatic stress ( p ) and the von Mises equivalent stress ( q ). FEA simulation showed that the mechanical properties of adhesives have a strong influence of the stress multiaxiality distribution of joints with elastic adhesive joints presenting higher levels of stress multiaxiality. Fracture surface analysis indicated cohesive failure for both types of adhesives. Static tests revealed that elastic adhesive joints are more sensitive to multiaxiality (i.e. higher hydrostatic stresses) than their structural counterparts, especially in samples with larger hindering of lateral contraction (butt and scarf joints). From fatigue SN curves, it was demonstrated how multiaxial p-q fatigue diagrams can be constructed. One of the main advantages of this approach is the possibility of predicting the fatigue lifetime of joints regardless of their

multiaxial stress state. Acknowledgements

This work is part of the Mat4Rail project, which has received funding from the Shift2Rail Joint Undertaking under the European Union’s Horizon 2020 research and innovation program under grant agreement No 777595. VC Beber acknowledges the funding from CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Nível Superior) through the Science without Borders program under the grant BEX 13458/13-2.

References

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