Numerisk simulering av tryckfält omkring 15,5 cm spränggranat: Bofors m/77

As a part of the project "Protective structures with focus on international missions" supported by the Swedish Armed Forces, numerical simulations of air shock waves around the topical 15.5 cm artillery shell were performed. For the simulations, the hydrocode AUTODYN (Ansys Inc.) was used. Calculated results and properties for the pressure field were compared with empirical values from literature (FortH2 [1], Proctor [2] and LS2000 [3]).The intention was not to achieve an exact model of the artillery shell but rather to develop a simple model to apply on calculations of pressure loads on different structures e.g. building facades, at a reasonable computational cost. With the suggested model, some numerical simulations were made that illustrates the pressure load distribution on building facades and its interaction with the ground plane for detonations in the near field. Cases with different height, distance and angle for the incoming shell were simulated. Sample results were compared with reported experiments with similar geometry (Palm [4]). Comparisons with formulas in the literature indicate that the suggested numerical model is likely to give enough good approximation of the pressure distribution and amplitude around the artillery shell for distances larger than 1 metre from its centre for pressure load studies on adjacent structures. The most striking result from the calculated pressure loads on building façades is the commonly occurring high loads on the lower part of the façade, near the ground plane. These loads also have a longer horizontal extension than higher up on the façade, at the level where the shell detonates.