This is a postprint version of the published document at:
Rodríguez-Millán, M., Vaz-Romero, A., Rusinek, A., Rodríguez-
Martínez, J. A. y Arias, A. (2014). Experimental Study on the
Perforation Process of 5754-H111 and 6082-T6 Aluminium Plates
Subjected to Normal Impact by Conical, Hemispherical and Blunt
Projectiles. Experimental Mechanics, 54, pp. 729–742.
DOI: https://doi.org/10.1007/s11340-013-9829-z
© 2013
Society for Experimental Mechanics.
Experimental S
tudy on the Perforation Process
of 5754-H111
and 6082-T6 Aluminium Plates Subjected to Normal Impact by
Conical, Hemispherical and Blunt Projectiles
M. Rodr´ıguez-Mill
´
an · A. Vaz-Romero · A. Rusinek · J.A. Rodr´ıguez-Mart´ınez · A. Arias
Abstract This paper presents an experimental investigation
on the perforation behaviour of 5754-H111 and 6082-T6
aluminium alloys. The mechanical response of these mate-
rials has been characterized in compression with strain rates
in the range of 10
−3
s
−1
< ˙ε<5 · 10
3
s
−1
.More-
over, penetration tests have been conducted on 5754-H111
and 6082-T6 plates of 4 mm thickness using conical, hemi-
spherical and blunt projectiles. The perforation experiments
covered impact velocities in the range of 50 m/s < V
0
<
200 m/s. The initial and residual velocities of the projec-
tile were measured and the ballistic limit velocity obtained
for the two aluminium alloys for the different nose shapes.
Failure mode and post-mortem deflection of the plates have
been examined and the perforation mechanisms associ-
ated to each projectile/target configuration investigated. It
has been shown that the energy absorption capacity of the
impacted plates is the result of the collective role played by
target material behaviour, projectile nose shape and impact
velocity in the penetration mechanisms.
M. Rodr´ıguez-Mill´an · A. Vaz-Romero · A. Arias
Department of Continuum Mechanics and Structural Analysis,
University Carlos III of Madrid, Avda. de la Universidad 30,
28911 Legan´es, Madrid, Spain
A. Rusinek
Laboratory of Mechanics, Biomechanics, Polymers and Structures
(LaBPS), National Engineering School of Metz (ENIM),
1 route dArs Laquenexy, 57078 Metz Cedex 3, France
J.A. Rodr´ıguez-Mart´ınez (
)
Department of Continuum Mechanics and Structural Analysis,
University Carlos III of Madrid, Avda. de la Universidad 30,
28911 Legan´es, Madrid, Spain
e-mail: jarmarti@ing.uc3m.es
Keywords AA 5754-H111 · AA 6082-T6 · Perforation ·
Ballistic limit · Energy absorption
Introduction
Impact and blast threats exist in a wide range of engineer-
ing, security and defence sectors. The protection of civil
infrastructures and critical industrial facilities are topics
of increasing relevance to defence agencies and govern-
ments. In the transport industry, energy absorption and
crashworthiness are key points in the design process of
vehicles, vessels and aircrafts. Development of protective
structures capable of sustaining an impact keeping the struc-
tural integrity is thus one of the main challenges of modern
industry. In the design and development of structural solu-
tions suitable for energy absorption under impact loading,
the material selection represents a crucial decision.
Within this framework, large efforts have been directed
in automotive, shipping and aircraft industries toward the
development of light-weight alloys (aluminium, magnesium
and titanium alloys) for high-performance dynamic applica-
tions. Enhanced by the increasing restrictions in fuel con-
sumption and the encouragement for emissions reduction,
there is an emerging trend to replace the conventional Fe-
based materials by these non-ferrous alloys in transportation
industry applications [1–5]. In particular, in the automotive
sector, aluminium alloys are now widely used in the manu-
facture of structural parts responsible for energy absorption
and crashworthiness [6–8]. The goal being to develop pas-
sive safety of vehicles through structures fabricated using
materials with the highest possible strength-to-weight ratio.
Important steps in this direction have been taken over
the last two decades and a vast body of literature has been
1
published on the mechanical behaviour of different alu-
minium alloys, see for example [9–12]. Within this context,
our interest is focussed on the experimental assessment of
aluminium plate products as energy absorbers in dynamic
penetration processes. It is worth noting a number of rel-
evant works published in this field by different authors
[13–22]. Primary interest in these papers is determining the
parameters affecting the ballistic capacity of the target. The
purpose is to correlate the penetration mechanisms with
the governing variables of the problem: target and projec-
tile characteristics (geometrical and mechanical) and actual
impact conditions (impact velocity).
The investigation reported in the present paper is pre-
cisely of this nature. Firstly, the mechanical behaviour of
5754-H111 and 6082-T6 aluminium alloys is characterized
in compression with strain rates in the range of 10
−3
s
−1
<
˙ε<5 · 10
3
s
−1
. Secondly, normal perforation tests on
5754-H111 and 6082-T6 plates of 4 mm thickness are con-
ducted using conical, hemispherical and blunt projectiles
with impact velocities in the range of 50 m/s < V
0
<
200 m/s. The goal is to illustrate the joint effect that target
material behaviour, projectile nose shape and impact veloc-
ity have on the penetration mechanisms. From the analysis
emerge two main ideas, which are the main innovative fea-
tures of this paper: (1) the penetration efficiency of a given
nose shape with regard to the others depends on the material
target and (2) the suitability for energy absorption of a given
target material with regard to other depends on projectile
shape and impact velocity.
Materials
The aluminium wrought alloys investigated are 5754-H111
and 6082-T6.
Aluminium alloy 5754 is a medium strength alloy with
excellent corrosion resistance especially to seawater and
industrially polluted atmospheres. H111 implies that the
alloy is work hardened by shaping processes. Aluminium
alloy 5754-H111 shows good cold formability, high fatigue
strength and fair machinability. It is within the alloys of
the 5xxx series of higher strength. This makes 5754-H111
highly suited to flooring applications, shipbuilding or chem-
ical and nuclear structures. It is also commonly used for
automotive structural members and inner body panels. The
chemical composition of the material (% of weight) is
reported inTable 1.
Aluminium alloy 6082 is a medium strength alloy with
remarkable corrosion resistance. T6 implies that the alloy is
heat treated and artificially aged. It has the highest strength
of the 6xxx series. Aluminium alloy 6082-T6 shows excel-
lent performance in machining operations. This grade sub-
stitutes to the conventional 6061 alloy in many structural
Tab le 1 Chemical composition of the AA5754-H111 (% of weight)
Mn Si Cr Cu Zn Fe Ti Mg
0.26 0.29 0.03 0.04 0.02 0.32 0.03 2.80
applications in which improved mechanical properties are
required. It is widely used in transport and structural appli-
cations in which high stress resistance is essential. It can
be found in the exterior of the planes fuselages and it is
a real alternative to conventional mild steel in automotive
body panels and structures. The chemical composition of
the material (% of weight) is reported in Table 2.
In order to reveal the mechanical behaviour of both
alloys under impact loading conditions, the flow character-
istics of the materials as function of strain rate have been
investigated.
Compressive Viscoplastic Response of 5754-H111
and 6082-T6 Aluminum Alloys under Wide Ranges
of Strain Rate at Room Temperature
Specimens used to perform the compression tests and tar-
gets used in the perforation experiments (see section “Perfo
ration Experiments”) were machined from the same plates.
The cylindrical compression samples, considered in both
quasi-static and dynamic tests, had the following dimen-
sions: diameter φ = 8 mm and thickness t = 4 mm.The
loading direction is the one corresponding to the thickness
of the plates. According to the considerations reported else-
where [24–27] the aspect ratio φ/t = 2.0 prevents from
significant friction and inertia effects. Additionally, sample
ends were lubricated to reduce friction effects during the
tests.
Quasi-Static Compression Tests
Low-rate compression tests were conducted using a servo-
electric testing machine within the range of strain rates 10
−3
s
−1
< ˙ε<10
−1
s
−1
. Figure 1 shows representa-tive quasi-
static compression stress-strain curves for both materials
tested. The magnitude of rate sensitivity is negli-gible for
both alloys within this range of strain rates, which
Table 2 Chemical composition of the AA6082-T6 (% of weight)
Mn Si Cr Ni Cu Zn Fe Ti
Mg
0.45 0.99 0.03 0.01 0.08 0.04 0.41 0.03 0.73
2
0
100
200
300
400
500
0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4
0.001
0.1
True stress,
σ
(MPa)
True strain, ε
0.001 s
-1
0.1 s
-1
Material: AA 5754-H111
0
100
200
300
400
500
0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4
0.001
0.1
0.001 s
-1
0.1 s
-1
Material: AA 6082-T6
True stress,
σ
(MPa)
(a)
(b)
True strain ε
Fig. 1 Representative quasi-static compression stress-strain curves.
(a) AA 5754-H111 and (b) AA 6082-T6
is a common characteristic shared by many commercial
aluminium alloys [28]. Furthermore, within this range of
strain rates the strain hardening exhibits almost negligible
dependence on the loading rate for both alloys investigated.
Moreover, Fig. 1 reveals that the AA 6082-T6 displays
larger yield stress whereas the AA 5754-H111 shows
greater strain hardening. The latter observation is
highlighted in Fig. 2 which shows, for both materials tested,
the strain hardening θ = ∂σ/∂ε versus the normalized flow
stress Y = σ/σ
0
,being σ
0
the material yield stress at the
onset of plastic deformation. The remarkable strain
hardening dis-played by the AA 5754-H111 boosts the
material flow stress and delays the flow saturation condition
(θ = 0).TheAA 5754-H111 is therefore expected to show
greater ductility than the AA 6082-T6, as it will be
discussed in forthcoming sections of this paper.
Dynamic Compression Tests
High-rate compression experiments with strain rates in the
range 7.5 · 10
2
s
−1
< ˙ε<5 · 10
3
s
−1
were carried out using
0
1000
2000
3000
4000
5000
00,511,522,53
B
D
Strain hardening, θ (MPa)
Dimensionless flow stress, Y
AA 5754-H111
AA 6082-T6
0.1 s
-1
Fig. 2 Representative experimental results: strain hardening θ versus
dimensionless flow stress Y for both materials tested
a conventional Kolsky apparatus (Split Hopkinson Pressure
Bar) made of high strength steel, which exhibits higher yield
stress σ
y
≈ 1000 MPa than that of the materials tested
under dynamic conditions of deformation. Detailed infor-
mation about the experimental arrangement can be found
in previous work of authors [25]. Note that in order to
determine the stress-strain curves, dynamic specimen equi-
librium (force equilibrium, energy balance) was verified for
each sample, and corrections for wave dispersion and fric-
tion effects were applied using a home-made program [29]
according to the conventional wave analysis.
Figure 3 shows representative dynamic compression
stress-strain curves for AA 5754-H111 and AA 6082-T6. As
previously determined from the low-rate experiments, the
strain hardening of both materials is nearly independent of
the loading rate. Moreover, it has to be noted that the flow
stress of both 5754-H111 and 6082-T6 slightly increased in
comparison with the value observed in the low-rate tests.
Figure 4 illustrates the flow stress at strain equal to 0.1
versus the strain rate for both materials analysed. The exper-
iments conducted in this work are plotted together with
those reported elsewhere [7, 28, 30, 31]. The flow stress is
largely strain rate insensitive until ε˙ ≈ 10
3
s
−1
. Beyond that
loading rate both materials show an incipient strain rate
sensitivity. This observation is consistent with the experi-
mental evidence reported elsewhere [26, 28, 32–34]where
it is shown that most commercial aluminium alloys exhibit
increasing rate sensitivity once a threshold loading rate
(typically within 10
3
− 10
4
s
−1
) is exceeded.
Perforation Experiments
The tested square plates were A
0
= 130 × 130 mm
2
with
a thickness of 4 mm. Their active surface area, after they
3
0
100
200
300
400
500
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
1535
3156
Material: 5754-H111
True stress,
σ
(MPa)
True strain, ε
1900 s
-1
3200 s
-1
0
100
200
300
400
500
0 0.1 0.2 0.3 0.4
1164
2588
Material: AA 6082-T6
1900 s
-1
2600 s
-1
True stress,
σ
(MPa)
(a)
(b)
True strain, ε
Fig. 3 Repr
esentative dynamic compression stress-strain curves. (a)
Material: AA 5754-H111. (b) Material: AA 6082-T6
were screwed and clamped to the support, was A
f
= 100 ×
100 mm
2
. The plate is embedded on a rigid support in such
a way that sliding effects are avoided during the impact
tests. This arrangement (screwing + clamping) used to fix
the plates in the impact tests has been proven to be effec-
tive avoiding any slippage at the supports as discussed in
previous works of the authors [35, 36].
Conical, hemispherical and blunt projectiles were used in
the perforation tests. Their geometries and dimensions are
shown in Fig. 5. In order to preserve the same initial kinetic
energy, the masses of the projectiles were constant: M
p
=
30 g. The projectiles were machined using maraging steel,
which exhibits higher yield stress – σ
y
≈ 2000 MPa
– than that of the materials tested under dynamic conditions
of deformation. In addition, the projectiles underwent a heat
treatment to increase their hardness.
To perform perpendicular impact tests on the aluminium
plates, a pneumatic gas gun was used. It should be noticed
that the diameter of the barrel was roughly equal to the
0
100
200
300
400
500
0,0001 0,001 0,01 0,1 1 10 100 1000 10
4
Work
Smerd
Jovic
Diane
Strain rate,
ε
Material: AA 5754-H111
ε=0.1
Fitting curve: expected behaviour
True stress,
σ
(MPa)
This work
Smerd et al. 2005
Jovic et al. 2006
Wowk 2008
room temperature
0
100
200
300
400
500
0,0001 0,001 0,01 0,1 1 10 100 1000 10
4
Work
Mocko
Material: AA 6082-T6
Strain rate,
ε
ε=0.1
True stress,
σ
(MPa)
This work
Mocko et al. 2012
Fitting curve: expected behaviour
room temperature
(a)
(b)
Fig. 4 Flow stress upon strain rate for ε = 0.1. (a) Material: AA
5754-H111. (b) Material: AA 6082-T6
diameter of the projectiles. No sabot was required for guid-
ance of the projectile inside the barrel, which helps to ensure
the perpendicularity of the impact.
(a) (b)
(c)
Fig. 5 Geometry and dimensions (mm) of the projectiles used in the
perforation tests. (a) Conical projectile. (b) Hemispherical projectile.
(c) Blunt projectile
4
