NUMERICAL SIMULATION OF THE WOOD RESPONSE TO THE HIGH VELOCITY LOADING .

The experiments where the freely supported spruce beams have been loaded by the detonation of an explosive charge have been evaluated using of the numerical simulation. The explicit Lagrangean finite element code LS DYNA 3D has been used to analyse the beam response. The wood has been considered as global orthotropic linear elastic material with a material damage. The material damage has been described by the strain at the wood failure. This simple material model seems be better than the Tsai - Wu model widely used in another numerical simulations. Spruce wood , beam , material damage, explosive loading, finite element , numerical analysis Wood is an anisotropic cellular material such as honeycombs, metal ring systems, polymeric foams and some others . These materials are very convenient for the design of impact energy absorbers and as core materials in lightweight structures. Their behaviour under static loading is well summarised in the book (Gibson and Ashby 1988). Wood in particular has also been used as a protective material for high velocity impact events for many centuries (Johnson 1986a, 1986 b) and is very often used as an impact energy absorbing material at the design of the transportation flasks for nuclear fuel etc. There have been only a few systematic studies of the behaviour of wood under high rates of loading following from some impact events (Johnson 1986a). Recently the extensive impact test data have been obtained for some wood species (Reid and Peng 1997, Harrigan et al. 1998) . These data have been used for the development of the models of the macro – deformation and micro – deformation modes resulting from the dynamic uniaxial compression at the specimen impact. The present paper focuses on the other kind of the dynamic loading which is the effect of the detonating explosive. The study of this problem has some practical applications . Wood may be successfully used as a part of a structure which should absorbed most of the energy of the mine explosion etc. It is obvious that there is a variety of different arrangements, kind of wood, thickness of wood layer etc. In order to reduce the number of expensive experiments some reliable numerical simulation is necessary. The present paper deals with the problem of such numerical analysis using of the finite element code LS DYNA 3D.