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Identification of Local Viscoplastic Properties in P91 Welds from Full Field Measurements at Room Temperature and 625 °C


A methodology to obtain visco-plastic laws in heterogeneous materials with digital image correlation (DIC) is proposed based on tensile and tensile-relaxation tests conducted at room temperature and at 625 °C. Tested samples are manufactured from a P91 weld in which a microstructural heterogeneity translates into graded mechanical properties. To simplify the problem, a classical decomposition of the weld into five different domains is considered. Strain field in each domain is obtained by means of digital image correlation applied to high magnification pictures recorded with an optical long distance microscope. The conducted identifications exhibit key features in the behaviour of each domain in terms of yield stress, ultimate tensile stress and hardening at both room temperature and 625 °C. Experimental fields are compared to the fields provided by finite element simulations. Eventually, the benefit of accounting for transverse strains in the identification procedure is examined, and the robustness of the procedure with addition of noise (representative of experimental conditions) in the measurement is characterized.

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Financial and technical support from Electricité de France (EDF), the Chair EDF, GDF Suez, GRT Gaz, Mines ParisTech and Ponts et Chaussées ParisTech called “durability of materials and structures for Energy” is aknowledged

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Correspondence to M. Touboul.

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Touboul, M., Crepin, J., Rousselier, G. et al. Identification of Local Viscoplastic Properties in P91 Welds from Full Field Measurements at Room Temperature and 625 °C. Exp Mech 53, 455–468 (2013).

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  • Identification
  • Heterogeneous materials
  • Full-Field measurements
  • P91 welds
  • High temperature