Protective structures with focus on international operations. Final report 2010-2013

Authors:

  • Rickard Forsén

Publish date: 2013-12-31

Report number: FOI-R--3750--SE

Pages: 17

Written in: Swedish

Keywords:

  • Fortifications
  • Hardened structures
  • Penetration
  • Shrapnel
  • Air blast
  • Structural response

Abstract

The R&T project "Protective structures with focus on international operations" have been going on for four years, 2010-2013. The main goal is to support the Swedish Armed Forces in the assessment of different structures performance after attack from conventional weapons. Activities focus on developing and maintaining methods and the ability to make such assessment. Current facilities can be different types of built structures such as protected barracks and camps, field fortifications, observation posts or other types of protection and shelters, but also tunnels and chambers in rock. Important phenomena treated during the project period is primarily the penetration process from fragments and penetrating warheads, air blast waves and structural response. Both experimental and numerical simulation work were conducted as well as compilation and analysis of previous work. Work has been completed and documented to describe the chain of phenomena of fragments generation, throw through the air and penetration process in materials. Special focus has been placed on documenting the work methodology for the experimental characterization of warhead fragment data. Penetration of fragment simulating projectiles in steel and concrete has been studied both experimentally and numerically. The ability to determine the penetration of warheads into concrete has been tested by comparing performed numerical calculations with previous penetration experiments with slender projectiles with good results. However, the models of penetration processes need to be further developed involving penetration phenomena of fragments and large projectiles in building materials especially in terms of combinations of materials in layered protection structures and the development of simple analytical calculation methods for both homogeneous materials and layered structures. Work on blast generation and propagation in air has focused on numerical calculations and analysis of detonating artillery shells and work has also been carried out in the form of comparative experiments in model scale also with good results. It is also important with future studies regarding pressure from thermobaric charges and other types of new compositions of explosives and explosive devices with different casings. Damage to more or less complex built structures from conventional weapons such as aerial bombs and artillery shells, but also improvised explosive devices, depends both on the blast pressure and on the fragments that are generated. Previous work has focused much of calculations and experiments to determine local damage and single component damage. To evaluate conventional weapons effects on more complex structures where several components are joined together, future work includes numerical simulation with simplified modeling of the structure and loads. The report describes the activities and results of the project and outlines some current projects with related activities.