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Comparative Study of Fragment Geometries.
KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.).
2012 (English)Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

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


Place, publisher, year, edition, pages
2012. , 111 p.
National Category
Applied Mechanics
URN: urn:nbn:se:kth:diva-103798OAI: diva2:561774
Subject / course
Solid Mechanics
Educational program
Master of Science - Engineering Mechanics
Available from: 2012-10-22 Created: 2012-10-22

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