Numerical analyses on missile impact tests performed at VTT within the benchmark project IRIS : modelling approach and preliminary results

In this EUR report the Finite element (FE) modelling approach and preliminary results of analyses on the recently performed VTT-IRSN Flexural Tests and the VTT-CNSC-IRSN Punching Shear Tests using the explicit FE solver RADIOSS are described. The FE analyses are carried out within the Benchmark Project "Improving the Robustness of Assessment Methodologies for Structures impacted by Missiles (IRIS)" of the Subgroup on Concrete of the Working Group on the Integrity and Ageing of Components and Structures (IAGE) of the Nuclear Energy Agency (NEA) of OECD. A Lagrangian modelling approach is chosen for the missile and the concrete slab. Special emphasis is put on the constitutive modelling of all involved materials. A special Drucker-Prager/Cap model, the model of Han and Chen, is used to model the constitutive behaviour of the concrete. Isotropic elastic-plastic constitutive models with strain-rate dependencies (where applicable) are used for steel reinforcements and missiles. The FE analyses give reasonable and sound results in view of the individual missile and slab characteristics. Main outcomes of the analysis concerning impact duration, deformation and damage of missile and slab, slab vibrations, etc... are physically sound. The results of the analyses clearly show that with today's available FE codes (and sufficient hardware) it is possible to predict the outcome of missile impact tests realistically. Nevertheless, more in-depth comparisons between test and analysis results need to be carried out when the test results are distributed to the benchmark participants.