Ductile damage under extreme conditions is a particularly complex multi-scale fracture phenomenon. In our laboratory, we develop dynamic damage model for material subjected to blast loading (very high pressure ~10 GPa and short solicitation time ~100ns). The dynamic damage is due to the interaction of two release waves. The high local tension induces the nucleation, growth and coalescence of multiple pores which can eventually break the sample.

Experimentally, cannon impacts on the plate, as well as laser shocks are performed. Measurements on time scales of the order of ten nanoseconds are a challenge in themselves. Only global macroscopic quantities such as the free surface velocity of ejected fragments are accessible to the experimenter. Post – mortem analysis under synchrotron radiation, Scaning Electron Microscope or profilometer provide valuable data to complement the in-vivo data.

Numerically a highly optimized molecular dynamic code, together with the exceptional computing power available at the CEA, allows atomic scales simulations of samples up to the micrometer scale (1 billion atoms) to tackle the porosity initiation, the interaction between pores and crystal defects and the short scale damage behavior. For larger scales, several codes simulate homogenized macroscopic models deduced from the up-scaling of the underlying porous structure.

Publications

1. Soulard, L., Bontaz-Carion, J., and Cuq-Lelandais, J.-P. Experimental and numerical study of the tantalum single crystal spallation. The European Physical Journal B 85 (2012) DOI
2. Trumel, H., Hild, F., Roy, G., Pelligrini, Y.-P., and Denoual, C. On probabilistic aspects in the dynamic degradation of ductile materials. Journal of Mechanics and Physics of Solids , 57 (2009) DOI
3. C.Denoual, and Diani, J. Cavitation in compressible visco-plastic materials. AIP Conf Proc Vol 620 (2002) DOI
4. Bontaz-Carion, J., Soulard, L., Lescoute, E., Sollier, A., and berthe, L. The x-ray micro-tomography backed by molecular dynamics simulations in the analysis of shock-induced damage in ductile materials. Material Science Forum 905 (2006) DOI

Researchers involved

J. Bontaz P. Bouteiller C. Denoual J.-L. Dequiedt A. Dubois Y.-P. Pellegrini L. Soulard