JEC COMPOSITES MAGAZINE - Issue #84 - October 2013 - 15

during the design phase so
that the material's performance can be validated before
on-demand fabrication.
The product is equally suitable for the fabrication of
flat, shaped, extra-large, or
mass-produced panels. The
production costs are low.
To produce this "reverse-engineered" design, the research
focused on:
- static and dynamic characterization of the material
and its components (foam/
needle-punched foam
bridge/plies),
- creating a numerical model
of the material,
- the material's numerical
design,
- the virtual creation of the
bridging and plies,

Multilayer sandwich BBOX before
finishing

- the numerical optimization
of the material and the plies
as a function of the threat,
- developing the manufacturing process (technology/
industrial definition/cost),
- testing (laboratory and
firing range).

Results
The first threat for which the
material was optimized and
assessed is of the explosively
formed penetrator (EFP)
type, combining a blast wave
(several kilograms of explosive at a distance of 1 metre
from the steel surface) and
the impact of a disk-shaped
liner weighing about a hundred grams at velocities of
more than 1000 m/s.
The protection design is a
combination one, from the
exterior to the interior: a steel
or aluminium plate, a "B²Box"
oriented bridge sandwich,
and a plate that is representative of the vehicle structure to
be protected.
The solution was compared
with other types of solutions
(metal and coupled metalcomposite liner) tested using
the same configuration. The
tests show that the structure
is deformed the least when
the B²Box solution is used,
and that the "B²Box" add-on

BBOX component ready to be installed

armour reduces the weight of
the extra protection by 13%
compared to an all-metal
solution, and also its thickness. Further optimization
would push the weight reduction up to around 20%. The
second threat considered was
of the buried landmine type
(weight: 6 kg). The comparison was made with a standard
all-metal flooring solution.
The B²Box considerably
reduced the dynamic deflection. Still, factoring a floor
protection by an oriented
bridge sandwich into the
vehicle design process would
help to optimize the protection against buried landmines.
The research project has resulted in an original solution,

More information

On June 5th at the prestigious Ecole Militaire de Paris, Karine Thoral-Pierre (Cedrem) and Jérôme Raynal
(PPE) received the 40th Ingénieur Général Chanson award for their work on "high-energy shock absorbing 3D
composite sandwich panels". The award was presented by Christian Mons, President of the GICAT (the French
Land Defence Manufacturers Association).
Their work provides an original solution for protecting vehicles, as well as buildings, against blasts and
impacts from improvised explosive devices (IED), with a weight saving of 15 to 20% compared with the
state of the art.
The Ingénieur Général Chanson award is given each year for advances the field of land armament, which
have a certain amount of innovation but are also sufficiently concrete to likely result in practical applications.
Winners are engineers working for the French defence procurement agency (DGA), military officers, engineers
from the military-industrial sector or people working in research laboratories.
The French general engineer Paul Chanson, a graduate of France's Ecole Polytechnique and a Doctor of
Science, is one of the fathers of the French nuclear weapons programme.

No84 October 2013 /

since the capacity to absorb
both blast wave and the
impact of projected fragments
shows much promise and
would help to limit the use of
heavy metal add-on armour
on vehicles. The material performs well as an energy absorber and greatly reduces the
impact on structures. Both
the potential 20% weight savings over the current state of
the art and the reduced cost
of the panels should attract
the attention of the designers
of vehicles that are currently
unprotected or insufficiently
protected (trucks, engineering vehicles), or used to
transport soldiers.
The research has other potential, as well: in the building
and civil industry, these
oriented bridge composites
could be incorporated into
construction or added to
existing walls to protect the
structure of buildings against
the effects of nearby explosions. Applications would
include, for example, protection for vulnerable accesses to
embassies. n
More information:
www.cedrem.fr
www.ppe-composites.fr

jec composites magazine 15

http://www.cedrem.fr http://www.ppe-composites.fr

JEC COMPOSITES MAGAZINE - Issue #84 - October 2013

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #84 - October 2013