Numerical simulation of shock wave propagation in air and structural respons from airblast, principal study

The aim of the study was to determine if the available methods could be used for design calculations, when experimental results are not available. The reason for this is because it is hard to obtain experimental data in several cases, i.e. full scale experiments and effects from weapons under development. Experimental data from earlier tests conducted at FOA with 48 kg charges were used for comparison with the numerical simulations. During these experiments shock waves from spherical charges and structural response for wall elements subjected to the air blast were studied. Simulations have mainly been performed with Autodyn 2D and 3D. The main focus of the study was determination of air blast pressures. However, simulation of structural response was also studied. The numerical results gave a relatively good agreement when with the experimental data. However, the calculated maximum pressure is sensitive to the used element size in the model. The error in the three dimensional models were -5% for the calculated pressure and -9% for the calculated impulse density. The final two dimensional model with Euler-FCT (Flux Corected Transport) formulation resulted in an average error of 0.2% for the maximum pressure and +3.6% for the impulse density. The local errors at the location of measurement points are both smaller and larger than the errors given above. According to this it should be possible to simulate shock wave propagation in air with Autodyn, and with the methods described in this report.