Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE credits
Fragments from explosive device have been and still are a great threat, but has now changed
into terrorist attacks involving IED (Improvised Explosive Devise) rather than hostile forces.
This master thesis will show the effects on concrete plates (50 mm depth) impacted by
different projectiles, which should replicate fragments hitting buildings. The projectiles used
were the 8 mm sphere, the 6 mm sphere, the 8 mm cylinder (RCC) and the FSP (fragment
simulating projectile). The thesis was made at request from FOI (Swedish Research Defiance
Agency) at Grindsjön and it contains both experiments made there and numerical simulations.
The experiments were conducted at Grindsjön, the projectile were fired in velocities between
800 m/s and 1600 m/s. The 8 mm and RCC obtains higher penetration depth at lower velocity,
while the FSP, due to its soft material, will need much higher velocity. Full penetration was
obtained at 1510 m/s for the 6 mm sphere, 1310 m/s for the 8 mm sphere and 950 m/s for the
RCC. The simulations were made in LS-DYNA using a meshfree solver (SPH) and the results
shows that the RCC creates a bigger initial elastic wave, which will make the concrete block
crack more, but it will also make the projectile lose more kinetic energy resulting in lower
penetration depth in the concrete. The spherical projectiles have higher penetration depth, but
it gives smaller elastic waves resulting in less cracking of the concrete. The simulations
overestimate the penetration depth for the non-flat projectiles while giving good agreements
for the flat projectiles, also the damage pattern are consistent with the experiments. An actual
fragment from a grenade was obtained and simulated showing that all of the projectile except
the RCC shows good agreements and therefore the RCC should not be used in simulating
2012. , 111 p.