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Authors
Advisor(s)
Abstract(s)
Extreme events, whether natural occurring or manmade can have catastrophic consequences,
endangering people. Given the current geopolitical situation, there is a need to better protect structures
against these threats, minimizing damage to critical infrastructure and safeguarding human lives. Due
to this necessity, the Research, Development, and Innovation Centre of the Military Academy
(CINAMIL) funded the “Protection of Infrastructures Subjected to Extreme Actions“ (PrISAEx) project,
from the Centre of Competence for Infrastructure Protection (CCPI), to better understand this
phenomena typology and to study ways to mitigate its effects. Within extreme events, hypervelocity
impacts (speeds greater than 2000 m/s or 3000 m/s) must be considered.
Therefore, this dissertation will study the behaviour of concrete when faced with hypervelocity
impacts, with the goals of evaluating the protective capabilities of concrete structures with the addition
of 3 layers of ceramic spheres. The hypervelocity will be achieved using a shaped charge inspired by
the PG-7VM warhead, launched by the RPG-7.
For this purpose, LS-DYNA was used to create axisymmetric numerical models of the shaped
charge impacting plain concrete targets, as well as concrete targets with the added ceramic spheres.
These models were validated with an experimental campaign where the achieved penetration, affected
diameter, entry diameter and loss of volume of the different targets were analysed. Furthermore, it was
possible to retrieve liners after opening the targets, which provided additional data regarding the loss
of their mass.
For the experimental campaign, 3 types of targets were used: S type targets, filled with plain
concrete; E type targets were filled with concrete with 3 layers of ceramic spheres and NN targets have
the same composition as E targets with the addition of a non-Newtonian fluid, filling the gaps between
the spheres.
With the experimental campaign, it was found that the addition of the spheres resulted in
decreasing penetration on target by 0,38% and that combining spheres and non-Newtonian fluid caused
a 20% reduction in penetration. Furthermore, it was possible to verify that the available analytical
penetration models significantly overestimate penetrations, which makes sense considering the
difficulties in translating the behaviour of a brittle and non-homogeneous material.
Description
Keywords
: Shaped charge Hypervelocity Numerical simulation Ceramic spheres.