The headers will be insert by the Publisher The headers will be insert by the Publisher The headers will be insert by the Publisher Meshless modelling of dynamic behaviour of glasses under intense shock loadings: application to matter ejection during high velocity impacts on thin brittle targets Y. Michel, J-M. Chevalier, C. Durin, C. Espinosa, F. Malaise and J-J. Barrau CEA-CESTA /DEV/SDET/LDDT – BP 2, F-33114 Le Barp CNES– BP 4025, 18 avenue Edouard Belin F-31055 Toulouse Cedex ENSICA - 1 Place Emile Blouin, F-31056 Toulouse Cedex 5. UPS-LGMT : Université Paul Sabatier, 118 route de Narbonne F-31062 Toulouse Cedex4 Abstract. The purpose of this study is to present a new material model adapted to SPH modelling of dynamic behaviour of glasses under shock loadings. This model has the ability to reproduce fragmentation and densification of glasses under compression as well as brittle tensile failure. It has been implemented in Ls-Dyna software and coupled with a SPH code. By comparison with CEA-CESTA experimental data the model has been validated for fused silica and Pyrex glass for stress level up to 35GPa. For Laser MegaJoule applications, the present material model was applied to 3D high velocity impacts on thin brittle targets with good agreement in term of damages and matter ejection with experimental data obtained using CESTA’s double stage light gas gun. 1. INTRODUCTION The various instruments used in the Laser MégaJoule (LMJ) experiment chamber will undergo many aggressions resulting from target disassembly. In this study, the authors only focus on potential impacts of debris and shrapnel on fused silica optical debris shields. The Main Debris Shields (MDS) are placed in front of each laser way out and thin Disposable Debris Shields, DDS, might be used to stop droplets and substantially reduce very small shrapnel cratering on MDS. But ejecta from the rear surface and penetration through the DDS are likely to damage the MDS and seed new laser damage sites. Space agencies face to an equivalent problem with the meteoroids and space debris. Ejecta or secondary debris, can contribute to a modification of the debris environment. The large solar arrays involving brittle materials as well as the importance of the ejected mass let suppose that they might play an important role in auto generation processes of the space debris population. To characterize matter ejection and to assess secondary impact threat, both experimental and numerical studies need to be performed. With the sight of modelling 3D impacts on brittle targets, the dynamic behaviour of glasses under intense shock loadings and phenomena that cause damages observed on impacted target need to be identified. CEA’s experimental facilities were used for the experimental part. On a numerical point of view, the severe deformations occurring in any high velocity impact event are best described by meshless methods since they offer advantages for modeling large deformations. To model matter ejection, the authors have chosen to derive and validate a material model coupled to Ls-Dyna/SPH method for both compressive and tensile loadings. This paper presents the dynamic behaviour of glasses, the material model derivation and its validation using an SPH method. Application to impacts SPH calculations are presented at the end of the paper.