Numerical simulations of blast loaded steel plates for improved vehicle protection

Sammanfattning: In the past decade, there has been an increasing demand from governments for high level protections for military vehicles against explosives. However, the design and validation of protection is a time consuming and expensive process, where previous experience plays an important role. Development time and weight are the driving factors, where the weight influences vehicle performance. Numerical simulations are used as a tool in the design process, in order to reduce development time and successively improve the protection. The explosive load acting on a structure is sometimes described with analytical functions, with limitations to shape and type of the explosive, confinement conditions etc. An alternative way to describe the blast load is to use numerical simulations based on continuum mechanics. The blast load is determined by modelling the actual type and shape of the explosive in air or soil, where the explosive force transfers to the structure of interest. However, accuracy of the solution must be considered, where methods and models should be validated against experimental data. Within this work, tests with explosive placed in air, soil or a steel pot have been performed, where the blast load acts on steel target plates resulting in large deformations up to fracture. For the non-fractured target plates, the maximum dynamic and residual deformations of steel plates were measured, while the impulse transfer was measured in some tests. This thesis focuses on continuum based numerical simulations for describing the blast load, with validation against data from the experiments. The numerical and experimental results regarding structural deformation of blast loaded steel plates correlates relatively well against each other. Further, simulations regarding fracture of blast loaded steel plates show conservative results compared to experimental observations. However, more work needs to be undertaken regarding numerical methods to predict fracture on blast loaded structures. The main conclusion of this work is that numerical simulations of blast loading on steel plates, leading to large deformations up to fracture, can be described with sufficient accuracy for design purposes.