TY - CONF A1 - Neumann, Martin A1 - Wille, Frank T1 - Modelling of compression of wood filled impact limiter of casks for transportation of radioactive material T2 - RAMTRANSPORT 09 - 8th International Conference on radioactive materials transport 2009 (Proceedings) N2 - Impact limiters of packages for transport of radioactive materials are in Germany typically steel-wood-sandwich-constructions, combining a relatively stiff steel structure bolted to the cask body, outer steel plates and different types of wood. By crushing the wood-steel-sandwich-structure between unyielding target and cask, kinetic energy of 9-m-free-fall is absorbed. Main energy absorber is wood under a high level of deformation. Wood under large deformations exhibits destruction of the fibre matrix. By analysing compression of impact limiter wood after drop tests with prototype casks for radioactive material, underlying mechanisms of wood crushing and corresponding energy absorption under large deformations are identified. Softening occurring at compression of wood is a function of lateral strain restriction of wood. Against the background of continuum mechanics an analogous model for compression of fibre bundle is presented. The model takes lateral strain restriction as triaxiality of stress state into account. Further modelling possibilities for wood with a continuum approach are described. Different material laws in the explicit Finite Element code LS-DYNA are analysed for possible application on the analogous model for the fibre bundle. Small scale compression tests with wooden specimens were modelled in order to evaluate the ability of different modelling techniques to simulate softening. Although modelling of compression of wood under large deformations is possible, softening could not be simulated purposefully. A drop test of a cask with impact limiting devices similar to existing impact limiters is simulated with different material laws for wood. Behaviour of impact limiting devices could not be simulated universally including influence of lateral strain restriction; nevertheless loading of the cask by crushing of impact limiter could be simulated purposefully. Verification with experimental results is compulsory. T2 - Ramtransport 09 - 8th International Conference on radioactive materials transport 2009 CY - Manchester, Great Britain DA - 2009-05-12 KW - Radioactive material KW - Transport KW - Impact limiter KW - Simulation KW - FEM PY - 2009 IS - PAP31 SP - 1 EP - 20 AN - OPUS4-19751 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -