Issue 30

V. Di Cocco et alii, Frattura ed Integrità Strutturale, 30 (2014) 462-468; DOI: 10.3221/IGF-ESIS.30.56 468 - DM, as a portable device, is able to observe the evolution of the damage in a pearlitic DCI, considering the graphite nodules as privileged, but not unique, observation points; - Damage is strongly influenced by the triaxiality. It is possible to suppose that nodule – matrix debonding is more important with higher triaxiality values (but this is to be confirmed by further investigations). Anyway, higher triaxiality values correspond to a 3D damage. Lower triaxiality values imply a damage that is mainly developed along the loading direction; - Slip bands become more and more important with the macroscopic deformation: the interfaces between nodules and matrix are the initiation sites of short cracks that propagate in the matrix. R EFERENCES [1] Dong, M.J., Hu, G.K., Diboine, A., Moulin, D., Prioul, C., Damage modelling in nodular cast iron, Journal de Physique IV, 3 (1993) 643-648. [2] Brocks, W., Hao, S., Steglich, D., Micromechanical modelling of the damage and toughness behaviour of nodular cast iron materials, Journal de Physique IV, 6 (1996) C6 43-52. [3] Guillermer-Neel, C., Feaugas, X., Clavel, M., Mechanical behavior and damage kinetics in nodular cast iron: part I. Damage mechanisms, Metall. And Mater. Trans. A, 31A (2000) 3063-3074. [4] Berdin, C., Dong, M.J., Prioul, C., Local approach of damage and fracture toughness for nodular cast iron, Engineering Fracture Mechanics 68 (2001) 1107-1117. [5] Liu, J.H., Hao, X.Y., Li, G. L., Liu, G. Sh., Microvoid evaluation of ferrite ductile iron under strain, Mater. Letters, 56 (2002) 748-755. [6] Gurson, A. L., Continuum theory of ductile rupture by void nuclear and growth, J Engng. Mater. Technol., 99 (1977) 2–15. [7] Tvergaard, V., Ductile fracture by cavity nucleation between larger voids, J. Mech. Phys. Solids, 30 (1982) 265–286. [8] Needleman, A., Tvergaard, V., Analysis of the cup–cone fracture in a round tensile bar, Acta Metall., 32 (1984) 157– 169. [9] Iacoviello F., Di Bartolomeo, O., Di Cocco, V., Piacente, V., Damaging micromechanisms in ferritic–pearlitic ductile cast irons, Materials Science and Engineering A, 478 (2008) 181–186. doi: 10.1016/j.msea.2007.05.110. [10] Di Cocco, V., Iacoviello F., Cavallini, M., Damaging micromechanisms characterization of a ferritic ductile cast iron, Engineering Fracture Mechanics, 77 (2010) 2016–2023. doi:10.1016/j.engfracmech.2010.03.037. [11] De Santis, A., Iacoviello, D., Di Cocco, V., Iacoviello, F., Graphite nodules features identifications and damaging micromechanisms in ductile irons, Frattura ed Integrità Strutturale, 26 (2013) 12-21. doi: 10.3221/IGF-ESIS.26.02 [12] Di Cocco, V., Iacoviello, F., Rossi, A., Iacoviello, D., Macro and microscopical approach to the damaging micromechanisms analysis in a ferritic ductile cast iron, Theoretical and Applied Fracture Mechanics, 69 (2014) 26– 33. doi: 10.1016/j.tafmec.2013.11.003. [13] Di Cocco, V., Iacoviello, F., Rossi, A., Cavallini, M., Natali, S., Graphite nodules and fatigue crack propagation micromechanisms in a ferritic ductile cast iron, Fatigue Fract Engng Mater Struct, 36 (2013) 893–902. doi: 10.1111/ffe.12056. [14] Di Cocco, V., Iacoviello, F., Rossi, A., Cavallini, M., Natali, S., Ecarla, F., Mechanical properties gradient in graphite nodules: influence on ferritic DCI damaging micromechanisms, Acta Fracturae, (2013) 222-230. [15] Di Cocco, V., Iacoviello, F., Rossi, A. Cavallini, M. Natali, S., Analysis of stress triaxiality influence: ferritic DCI damaging micromechanisms, Acta Fracturae, (2013) 1-8.