PSI - Issue 17

M. Carrera et al. / Procedia Structural Integrity 17 (2019) 872–877 M. Carrera, P. Lopez-Crespo, P.J. Withers/ Structural Integrity Procedia 00 (2019) 000 – 000

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4. Conclusions

• A new procedure has been presented in this paper, to estimate the plastic zone in the bulk of opaque materials. The procedure employs crack tip strain fields in the crack opening and crack growing directions, as well as shear strain fields. • Measurements made with XRD take data from a volume through the thickness, inside the sample studied. This method ensures a proper penetration inside the material. Nevertheless, data obtained is referred to a volume inside it, instead of a single plane. Plain strain conditions have been assumed because of the large thickness of the sample and the main data being acquired in the mid plane through the thickness. • The predicted plastic zone shape agrees well with the plane strain models employed. The size of the plastic zone obtained with the current model appears to be smaller than that of the theoretical solutions, probably due to the gauge volume effect. Higher accuracy in the plastic zone estimation could be achieved by increasing the resolution of measurements during the XRD experiment.

Figure 3: Thresholding of the strain data to produce the experimental plastic zone (coloured in black) obtained from the equivalent stress field, and comparison with plain strain and plain stress models, at 30.000 cycles.

Acknowledgements

We are grateful for the beam time granted by the ESRF (MA1488). We would also like to acknowledge the economic support by the Spanish Ministry of Economy and Competitivity, through their grant reference MAT2016 76951-C2-2-P, as well as to the European Research Council Funding grant nº695638, the EPSRC grants nº EP/M010619, EP/K004530, EP/F007906, EP/F028431 and EP/I02249X/1, and the European Social Found, through its Youth Employment Initiative, grant reference UMAJI84.

References

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