An Industrial Challenge Based on the Wave

Transcription

An Industrial Challenge Based on the Wave Propagation : the
Shock Adhesion Test
Michel Arrigoni, Jean-Paul Cuq- Lelandais, Michel Boustie, Elise Gay, Laurent
Berthe
INTRODUCTION
An increasing number of applications involves coated systems and adhesively bonded
materials. Therefore, coating deposition methods, glued assembly process and bond
strength measurement techniques are more and more needed in the industry. A
conventional approach could consist in testing one sample out of a certain quantity in
order to check the quality of the assembly during the production.
Examples Of Coated Parts In The Industry
The internal rota-plasma technique is used by Sultzer-Metco for coating the inner
cylinder bore (fig. 1.a) of engine block in the automotive industry (Barbezat, 2001). This
technique consists in spraying, at high velocity, metallic particles that forms a coating
when impinging the cylinder bore. It is able to treat a cylinder bores of 80 mm diameter
and length of 120 mm with a coating of few hundreds of microns in less than one minute.
This new economic process leads first to size and weight optimisation and then to an
enhanced production pace.
In medicine, hip prosthesis are made of a titanium alloy (TA6V) coated with a ceramic
named Hydroxy-apatite (HA). This couple of materials insure an enhanced longevity
because of its in vivo compatibility with human tissues, however, the assembly has to be
reliable. The challenge consists in coating the ceramic on the titanium alloy. The
Hydroxy-apatite is plasma sprayed in the titanium alloys. Some samples were prepared in
order to evaluate the bond strength between the coating and the substrate (Guipont et al.
2010). Few hundred millimetres of HA were deposited on a substrate of TA6V, having a
thickness of the order of the millimetre. The sample was submitted to a laser adhesion
test and was then recovered (fig. 1.b).
The industry of metal transformation and metal forming uses drawing and wiredrawing
processes for reducing the section of a rod or a bar. The rod has to pass through a mould
that has to combine a strong hardness and good heat transfer ability. The mould is thus
made of copper hardened with chromium or nickel on its active surface. The deposition
method used for manufacturing such a mould can be the electro-deposition: the mould
becomes an electrode in a bath of electrolyte made of a solution of zinc oxide and an
oxydo-reduction reaction at the electrode makes a zinc deposition on it (fig. 1.c). In this
industrial situation again, the assembly has to be reliable.
Adhesion Measurement Methods
A definition of the adhesion is given in the French Standard NF T 76-001 (1981) as being
chemical, physical or physic-chemical phenomena at the origin of the union of two or
more materials. This union can be either due to an anchorage, or to the use of an extra
material called “structural adhesive”. Conventional adhesion evaluation methods have
born since the beginning of the industrial era. They aim at measuring the integrity
threshold of two joined parts submitted to stresses.
AcademyPublish.org - Wave Propagation
605
Figure 1: a. Half cylinder bore coated by rota-plasma technique, b. Sample of TA6V
coated with HA, recovered after shock adhesion test, c. Partial cut of a mould for
wiredrawing, made of copper coated with zinc by electro-deposition.
 a)



 c)
b)
Depending on the methods, this threshold can be either practical adhesion work, or
propagation energy, stress, … and then the measured “adhesion level” highly depend of
the method used. Different authors have proposed reviews of these tests (Chalker et al.,
1991; Lacombe, 2006; Da Silva, 2011).
Since conventional testing methods are destructive, the operated test is not extended to all
a production, that is to say wrong assemblies may pass between two tests. However,
weaknesses are unacceptable in the case of high added value products like aircrafts, space
equipments or cars that must to be very reliable. In order to overcome this drawback, non
destructive techniques (NDT) were developed. They allow a local control of defects in a
part but they do not provide quantitative information of the bond quality. In order to
overcome the weaknesses of the NDT, shock adhesion tests (SAT) have been proposed.
They can provide a quick diagnostic of an assembly and are not only able to test locally
the integrity of the assembly (coated or glued), by a wave propagation approach, but also
to estimate its “adhesion level”.
The present chapter proposes first a description of shock adhesion tests. Then a short
description of the shock wave mechanics is given. This chapter also shows results from
experiments obtained on realistic samples are presented. Samples were prepared by
considering various interfacial roughnesses. Various deposition methods were also tested:
sprayed coatings, electrodeposited coatings, glued assemblies. Results point out the
effects of interface roughness, the deposition parameters and the porosity of the coating
upon traction yielded at the interface. A porous model is proposed and is implemented in
a numerical code for lagrangian hydrodynamic simulations. Results are compared with
other conventional testing methods like the bond pull test (traction, quasi-static, 1D) and
the bulge and blister test (mixed mode, with crack initiated). Adhesively bonded samples
involving various glues were also tested. Limitations met by this technique are presented
and discussed. Variants are proposed in order to overcome these limitations.
Shock Adhesion Tests
In the early seventies, ultrasonic techniques using piezo-transducers (Tattersall, 1973)
were successfully exprimented in order to detect defects in assemblies, bulk parts or in
order to characterize a material. At this time, the LASER (acronym for Light
Amplification by Stimulated Emission of Radiation) was recently discovered and the
optical pumping method described by Kastler (Nobel prize for Physics, 1966) allowed the
laser to produce energetic pulses in a wavelength that depends on the medium excited for
the stimulated emission. Askaryon (1963) experienced the vaporization of the surface of
606
a condensed material irradiated by a laser. From this time, two directions were
prospected.
In on hand, some researchers focused on the ablative regime (i.e. laser induced shock
waves). Anderholm (1970) measured that the generated pressure could reach tens of
kilobars when the irradiated surface is covered of a confining layer, like water. The
effects of laser induced shock waves on condensed matter were then prospected and the
virtues of the laser shock processing (LSP) were described by Clauer et al. (1981). The
laser induced shock waves were strong enough to damage materials (by the phenomenon
of spallation explained in section “shock wave mechanics”). Vossen (1978) tried the first
the laser spallation technique applied to the bond strength measurement of a coating on
its substrate.
On the other hand, some researchers explored the thermo-elastic regime (i.e. laser
ultrasonics). White (1963) and Scruby et al. (1980) described the acoustic waves
generated by a pulsed laser on the condensed matter. Loh et al. (1986) experienced the
adhesion evaluation of a ceramic coating on its substrate by the use of a thermo-elastic
laser induced waves.
A third thematic involving the use of laser systems was of a crucial need: laser sensing.
Indeed, the advent of the laser interferometers allowed to sense physical values like
displacement and velocity. Among them, the VISAR (Velocity Interferometer System for
Any Reflectors) designed by Barker et al. (1972) was used in order to sense the rear
surface velocity (the one in vis a vis of the irradiated face). It is important to keep in mind
that is is a ponctual measure. From the analysis of the temporal evolution of the free
surface velocity, a diagnostic can be done on the integrity of the tested sample.
Monchalin (1989) proposed a Confocal Fabry Perot interferometer able to sense a
displacement of the order of the nanometre. He is also the author of a review about the
optical detection and generation of ultrasound (2003).
Once these precursors had opened the road towards the shock adhesion tests, Techniques
gathering laser generation coupled with laser detection were developed. Methods has
been patented by Gupta in 1995 and Sokol et al in 2005, which consists in coupling the
laser shock generation, in confined regime (using an absorbing layer and a baking layer),
with a laser Doppler interferometer. The signal sensed at the free surface was then
interpreted for estimating the interfacial strength and interfacial rupture energy.
Since this last progress, the feasibility of laser shock adhesion test has been evaluated on
various couple of substrate and coating materials.
Most of authors focused on thin films adhesion testing, that is to say films were about
few microns thin or less, (Epishin et al., 1988; Gupta et al., 1992; Tang et al., 1996;
Youtsos et al.. 1999; Zhou et al., 2002). Wang et al. (2004) experienced this technique in
mixed mode on sub-micronic Al films on silica substrates. They could observe that the
interfacial strength is higher when solicited in mixed mode and deduce strength in normal
mode of about 500 MPa. Gupta (2003) proposed a glass modified laser induced shock
wave for debonding thin films coated on thin substrates. The substrate coated can be
thinner than 1 µm and is attached to the glass layer in contact with a sacrificial
aluminium layer of 0.5 µm that will be vaporized during the laser-matter interaction, and
the plasma expansion resulting will be confined by a 15-20 µm SiO2 layer. The thinness
of films that he could tested was as thin as 185 nm and he could determine a bond
strength as high as 2.7 GPa. The laser adhesion test is indeed one of the most suitable
methods for testing the adhesion of thin films, since thin films cannot be handle with
mechanical instruments and cannot be load in any conventional testing machine. These
experiments do not require having a powerful laser source (less than 1 joule) and thereby
are accessible to industrials. Their results converge towards the fact that the laser shock
adhesion test is rather well adapted for the evaluation of the adhesion of thin coatings on
substrates thinner than 1 mm.
607
When the total thickness of the assembly become too high (above 1 mm), because of the
transience of the impulse, the shock pressure decreases drastically during its propagation
in the sample. So, the stress available for debonding the coating becomes too weak. This
phenomenon, know as hydrodynamic decay is explained (section “shock wave
mechanics”).
Some authors investigated solutions in order to overcome to this physical limitation and
extend the laser adhesion test to thicker samples. They, first, used high energy pulsed
laser providing several joules. Boustie (1999) and Auroux (2001) succeeded in using high
energy pulsed laser for debonding platinum coatings which the thickness ranged from 5
to 70 µm deposited on a Hastelloy X Steel substrate as thick as 500 µm. They used a 100
Joules laser source for generating the shock and made a VISAR diagnostic on the coating
debonding. Baumung (2001) estimated the cohesion and the bond strength of a plasmasprayed metallic alloy on an Inconel substrate. Rosa (2002) proposed a model for
estimating the bond strength, the stress intensity factor KIC and the energy release rate
GIC, on alumina 200 µm thick plasma-sprayed on 5 mm thick steel. They could validate
their results with the bond pull test and the bending test. Kobayashi (2004) could debond
up to 140 µm of zirconia plasma-sprayed on a 2 mm thick S304 Steel. They could
determine the bond strength between 200 and 500 MPa depending on the layer
thicknesses. The reader should note that bond strength deduced from these techniques are
much higher than the ones determined by conventional methods (below 100 MPa). Bossi
(2005) proposed a bond inspection technique for aeronautical parts likely to be affected
by “kissing bonds”, i.e. defective bonds that cannot be detected by ultrasonic inspection
but that can be opened by laser shock adhesion test.
The open literature does not mention the effect of surface roughness, intermetallic phases,
porosity and sample thickness on the laser adhesion test. There is still a physical
limitation due to the shock attenuation and the technique is then limited to millimetric
samples. The matters tackled in this chapter will propose some results about the work
performed by a group of researcher in the frame of a research project, lead from 2001to
2005 and entitled LASAT, which stands for LASer Shock Adhesion Test!
SHOCKWAVE MECHANICS
This section does not pretend to expose a detailed theory of shock waves. Only a
simplified approach is given in order to understand how LASAT works. One can deepen
its knowledge about shock waves by reading some dedicated literature (Zel’dovich, 1969;
Meyers, 1996; Antoun et al., 2005; Davison et al., 2008). Moreover, the shock waves
generated in the LASAT are laser induced, so it is a particular subsection of shock wave
mechanics.
Sonic Waves
A simple definition of an acoustic or mechanic wave would be a thermodynamic
perturbation that propagates in a medium. When the perturbation transports infinitesimal
variations of pressure, particle velocity, energy, density, the thermodynamic
transformation carried by the wave and communicated to the propagation medium can be
considered as reversible, adiabatic and isentropic. The wave is then considered as a sonic
wave and its celerity can be expressed from the isentropes in the plan (pressure, density)
or (pressure, specific volume) by relation (1) :
c=
608
∂p
∂ρ
=- v
s
∂p
∂v
(1)
s
Let’s consider an elementary volume of section S (fig. 2), in lagrangian coordinates. Its
initial state is described by subscripts 0 like u0, the particle velocity, P0, the pressure, ρ0
the density. After an elapsed time dt, the wave has progressed of (c-u0).dt and leaves
behind it a state subscripted 1 in the propagation medium. By applying the Newton’s
second law to the elementary volume, one can write (2) on projection on axis x:
ΣF = (P1 – P0). S = m.a
(2)
Where m is the mass of the elementary volume and by observing figure 2, one can
deduces that m = ρ0.S.dx. Acceleration a can also be written as the temporal derivative of
particle velocity u. External forces F applied on the monitored volume are only due to
pressure forces on axis x, thus, ΣF = (P1-P0).S = dP.S what can be written, according
what has been said as (3) :
dP = ρ0.dx
with
c=
so
dP = ρ0.c.du
(3)
Figure 2 : wave propagation in a monitored volume (monodimensional).
(c-u0).t
x0 + dx
(u1-u0).t
t = t0+dt
x0
c
S
P0, u0, ρ0
P1, u1, ρ1
t=t0
x
t=t0+dt
Shock Formation
Let’s make a basic assumption that says wave celerity increases with pressure. In the
situation of propagation of the rising front of a pressure pulse, shown in figure 3.a,
P2>P1, thus, considering the above assumption, u+c(P2) > u+c(P1), the rising front is
going to be steepened. By the same analysis on the falling front (fig. 3.b), P2 < P1, so
u+c(P1) > u+c(P2), the falling front is going to be flattened.
So, it can be generalized that a release wave sprawls and a compressive wave steepens.
This mechanism can be seen as the base of the creation or the damping of a shock wave.
Figure 3 : evolution of a sonic wave.
a) P
2
P1
b)
u+c(P2)
P1
u+c(P1)
P2
x
u+c(P1)
u+c(P2)
x
The Rankine-Hugoniot Equations
In these demonstrations, shock fronts are considered absolutely steep, the flow is
considered along the axis x and no effects of the elasto-plastic behavior are taken into
account, neither resistance to shear. The gravitational force is neglected and heat transfers
as well because they are too slow compared with the shock propagation. The medium is
not likely to undergo any phase transition. The flow is then said as in hydrodynamic
regime. It is a convenient description for high pressure.
609
Masse Conservation. The description of a monitored volume under shock is given in this
subsection. The velocity of the shock transforming a medium at state 0 into a medium at
state 1 is noted D01 in the referential linked to the material at initial state or D = D01 + u0
in the absolute referential. By applying the mass conservation to the situation shown in
figure 4, between t0 and t0+dt, the mass of the monitored volume before shock, ρ0.S.AB is
equal to the mass of the monitored volume under shock ρ1.S.A’B’, what can be written as
(4) :
ρ0.(D-u0) = ρ1.(D-u1)
or
ρ0.(D01) = ρ1.(D01+u0-u1)
(4)
Momentum Conservation. The momentum of a body is the product of its mass by its
material velocity. The impulse is the product of the force by a time interval. The impulse
given to the monitored volume is due to the action of pressure forces on the sides. So, the
difference of momentums between states 0 and 1, (ρ1.S.(D01+u0-u1).dt.u1 - ρ0.S.D01.dt.u0),
is equal to the external impulse given to the system during the time dt, (P1-P0).S.dt. By
using relation (4) in this equality, it comes (5) :
P1-P0 = ρ0.D01.(u1-u0)
(5)
Energy Conservation. The work W of forces exerced on the system (only pressure
forces) during dt,is equal to the variation of the total energy Σ (kinetic Ec and internal Ei).
The heat is not taken into account since we assumed that the system is adiabatic, thus
W=P1.S.u1.dt-P0.S.u0.dt and ΔΣ=W=ΔEc+ΔEi. The variation of kinetic energy is
expressed as follow : ΔEc= ½(ρ1.S.A’B’. - ρ0.S.AB ).dt .
If E is the internal specific energy, then ΔEi=E1. ρ1.S.A’B’.dt-E0 ρ0.S.AB.dt .
By using (4), it is deduced that (6) :
P1u1-P0u0 = ½ ρ0D01.
+ ρ0.D01.(E1-E0)
(6)
This expression can be transformed again by using equations (4) and (5) for being written
in a more common way (7) :
E1-E0=½(P1+P0)(v0-v1) with v=1/ρ
(7)
Equation Of State
Equations (4),(5),(7) constitute a system involving three thermodynamic variables
(pressure P, density ρ, energy E) and two kinetic variables (particle velocity u, wave
velocity D). Two more relations are needed to completely determine a state under shock.
One relation used in shock physics is the Mie-Grüneisen equation of state (8).
Γ
(8)
P(E,v) - P ref (v) =
(E - E ref (v))
v
The Mie-Grüneisen equation of state gives the accessible pressure in the space (P, ρ, E).
610
Figure 4 : Transformation of a medium by a shock wave.
A
B
t = t0
P0, u0, ρ0
D01.dt
(D-u
0).dt
A’
u1.dt t = t +dt
0
u0.dt
B’
P1, u1, ρ1
S
Shock front
P0, u0, ρ0
S
(D01+u0-u1).dt
(D-u1).dt
An independent relation is still needed. In the shock literature an empirical relation D(u)
is often given as (9) :
D01=C0+s.(u1-u0)
(9)
With C0 the bulk velocity and s an empirical coefficient deduced from experiments. Both
are intrinsic values of a chosen material. C0 is often calculate from Cl and Ct, that are
respectively the longitudinal and the transversal sound speed, as (10) :
c0 = cl2 -
4 2
c
3 t
(10)
By using relations (4,5,9), one can show that (11) :
v1
)
v0
PH - P0 =
v1
v0.[ 1 - s .( 1 - )]²
v0
c0 2 .( 1 _
(11)
Where PH is the Hugoniot pressure describing the pressure accessible to a material at a
given density, plotted in thin line in figure 5.
Constitutive Laws
Equations mentioned previously only describe the hydrodynamic behavior which would
be sufficient for pressure much higher than the quasi-static elastic limit Y0. A dynamic
elastic limit can be define as the Hugoniot Elastic Limit by equation (12) :
c l2
1- p
= Y0
1- 2 p
2c t2
Where p is the Poisson coefficient.
σ HEL = Y0
(12)
The perfect elasto-plastic model would work and modify the Hugoniot curve in the plane
(P,v) or (σ,v) as shown in figure 5. This figure shows that for stresses just above σHEL, the
velocity of the elastic wave is higher than the one of the plastic waves. As a consequence,
611
in a compressive wave, the wave front is divided into two steps : the first step called
elastic precursor, and the second step called the plastic wave. There is a critical density
for the one the slope of the curve (σ,v) becomes higher than the value of cl. At this point
the shock front is only one rising edge.
Figure 5: Hugoniot curve in plane (P,v) or (σ,v) with and without elasto-plastic behavior.
σ,P
H
σ,P
H
Y0
σHEL
c0
cl
Y0
v0 v
x
More sophisticate models can be found in the literature for describing the dynamic
behavior of materials. One of the most famous, because available in most of numeric
codes is the semi-empirical model of Johnson-Cook (1983) that takes into account the
effects of temperature and strain rate. However, some others give good results like the
one of Steinberg et al. (1980) in which the Yield limit and the shear modulus are Pressure
and temperature dependant. Zerilli et al. (1987) proposed a model based on the mobility
of dislocations, and is particularly adapted for centered cubic and centered face cubic
crystals.
Transmission And Reflection Of Shocks
The LASAT process is based on the propagation of shocks into a part composed by
different materials. The shock front is supposed parallel to surfaces (shocked and free)
and interfaces so that the problem can be treated as “frontal impact”. Oblique shock
waves are treated differently; a convenient approach is given by Thouvenin (1996).
By including equation (9) in equation (5), one obtains a polynomial expression of
pressure versus particle velocity, called the shock polar. In the exposed approach, the
determination of a state resulting from an impact or a shock transmission or reflection
between two mediums, is based on the shock polars intersection. The assumption that the
release polar is the symmetric of the shock polar, which is physically false, but very
convenient for the analytic approach, the error is below 10 % when shock pressures are of
the order of the ones involved in LASAT.
Wave events can be followed on a space-time diagram (Lagrange diagram), figure 6.a.
When a shock pressure P1 is applied on the impacted face, a shock wave propagates in
the sample, towards the rear surface (free surface), with a velocity D01. It transforms
material A at initial state 0 to state 1. When the pressure loading is released, release
waves propagate behind the shock wave, at velocity c1+u1 that is greater than D01. When
the incident shock waves interacts with a new medium, it is transmitted as a shock wave,
let’s call its velocity D02, and reflected as a wave depending on the impedance mismatch
between material A and B. The acoustic impedance Z is defined as being the product of
the sound velocity by the density of the material. If ZA < ZB, the shock wave is reflected
as a compressive wave. The thermodynamic equilibrium imposes from each side of the
interface that pressure and material velocity in material A at state 2 are equal to those of
material B at state 2 (fig. 6.a). So state 2 can be determine by considering it belongs to
the polar of material B initially at state 0 and to the polar of material A, going towards the
negative x (as the sound and material velocities are algebraic values) and passing by state
612
1, which is the medium in which the wave propagates (fig. 6.b). Thereby, the intersection
of both polars gives state 2. In figure 6.b, pressure increases so it means that the wave
transforming state 1 in state 2 is a compressive wave. We ca perform the same approach
in the case ZA > ZB. Then, pressure decreases from state 1 to state 2, the reflected wave is
a bundle of release waves.
Figure 6 : a. Space-time diagram of wave propagation in a sample composed of material
A with ZA > ZB. b) P-u diagram corresponding to ZB > ZA. c. Space-time diagram of wave
propagation in a sample composed of material A with ZA < ZB. d) P-u diagram
corresponding to ZB < ZA.
a)
t
-D12+u1
c3+u3
b) P
2
c1+u1
D01 1
0 A
2
D02
P
c) P
t
-c2+u2
-c1+u1
c3+u3
1
c1+u1
0
A
u
ZB<ZA
A
B
D02
P2
0
B
x
P
D01
2
u1
A'
P1
2
A
u2
x
d)
ZB>ZA
P2
P1
0
B
B
A"
u1
u2
u
The monodimensional assumption would be reasonable, at least at the early stage of the
propagation, as long as the diameter of the shocked area will be more than 3 times higher
than the sample thickness. After a while, edge effects will appear. In theory, the available
tensile stress at the interface is supposed to be close to the initial shock pressure.
However, it is not the case when a short pressure impulse propagates, because of
damping.
Hydrodynamic Decay
As shown in figure 6, the unloading process induces release waves that propagate faster
than the main shock wave. The head of the release wave propagates at C1+u1, the tail
propagates at Co+u0 while the shock wave propagates at D01 + u0. By keeping in mind
that Co+u0 < D01 + u0 < C1+u1, the shock will be caught up by release waves that will
interact with the shock and decrease its intensity. In the case of “flat top” pressure pulse,
the “catch-up” distance Xc depends on the pulse duration and the shock pressure or
velocity.
Figure 7 : Hydrodynamic decay and “catch-up” distance.
P
P
C1+u1
P1
Co+u0 < D01 + u0 < C1+u1
Hydrodynamic
decay
D01
v
C0+u
0
Xc
x
613
Spallation Process
This subsection describes the spallation phenomenon. It is extensively presented by
Antoun et al. (2003) only a short description is given here. A pressure impulse is applied
on a target composed of a single material (fig. 8.a), for example by a plate impact
experiment. A shock wave then propagates in the target, reaches the free surface and is
reflected towards the loaded face as bundle of release waves, creating state 3. When the
unloading occurs, it also propagates a bundle of release waves, giving state 2, superposed
with state 0. When the two bundles of release waves cross each other, it appears on the
diagram (P-u) a state 4 for which the pressure is negative (fig. 8.b), which is actually a
tensile state. If this tensile is high enough, it is able to crack the material, giving place to
a spall (fig. 8.c). Waves are isolate in the left part of the material, doing back and forth,
that change the recorded free surface velocity, usually by a laser Doppler interferometer
(Barker et al., 1972; Arrigoni et al., 2009).
Figure 8 : a. space- time diagram and. b. P-u diagram of a spall event. c. cross section of a
recovered spalled sample of Al 500 µm irradiated at 199 GW/cm² (about 90 kbar).
a)
t
b)
4
3
2
0
x
c)
1
3
0, 2
u
spall
Pressure
4
P
1
P
Some Damage Models
Spall fracture and damage models are also well described by Antoun et al. (2003). Only
an overview is given in this subsection. The simplest damage model is the cut-off model.
This criterion makes the material crack as soon as the tensile stress exceeds a critical
value. Although it is a simple to implement in a finite element code, it is not realistic for
ductile fracture. A more sophisticate model, proposed by Tuler-Butcher (1968) consists
in considering cumulative effects, and once a threshold reached, the damage appears. It is
governed by equation (13) :
time
I = ∫ ( σ - σ critl ) A dt
0
(13)
If σ > σ crit then if I=K fracture is occurring. That is to say there are three coefficients A,
K and σcrit that govern the model. Unfortunately, there is no unique trio of A, K and σcrit
for a given material.
Kanel et al. (1987) also proposed a remarkable global model that takes into account the
degradation of yield limit, shear modulus, critical stress and pore growth during the
damage stage.
LASER INDUCED SHOCK WAVES
Laser-Matter interaction allows creating extreme pressure (Mbar) and temperature during
an extremely brief time (femtosecond). The light from the pulsed laser is focused on a
condensed surface and the temperature and pressure elevation is important and brief so
the matter is locally sublimated, thereby, plasma is generated at the surface (fig. 9). By
the principle of action and reaction, the throttle of the plasma expansion at the surface of
the matter engenders an intense pressure (Trainor et al, 1978; Gardan-Labaune, 1982).
614
Direct Irradiation
Several authors prospected the ability of generating extreme pressures from high energy
pulsed laser (Grün et al. 1981; Fabbro et al. 1985; Phipps et al., 1988). They could
converge towards the expression of pressure P in function of wavelength λ, the density of
power  and the pulse duration τ (14) :
Pmax = K m n p
(14)
Where K, m, n and p are coefficients that depend on the nature of the irradiation
(confined or not) and the nature of the material. The density of power is defined by (15) :
E
(15)

 .S
With E the maximum energy and S the irradiated area.
So, with laser sources available in some laboratories, it is possible to generate extreme
pressure in thorough vacuum conditions (several TPa). However, they are not accessible
to industrials and are very expansive.
Confined Irradiation
Some authors focused on the laser-matter interaction with a transparent confining
medium interposed between the laser beam and the irradiated surface that retains the
plasma expansion. It results an increased pressure (from 5 to 10 times higher) and
duration (from 2 to 3 times longer) (Berthe et. al, 1997; Sollier et al. 2001). The authors
proposed a model giving pressure P in function of the density of power and the relative
acoustic impedance Z (16) :
P(kBar)  0.1

Z ( g.cm  2 .s 1 )  (GW / cm 2 )
 3
(16)
2
1
1
and α is the percentage of incident density of power
=
+
Z Z water Z material
absorbed by the laser-matter interaction. Usually, α is between 0.2 and 0.25.
With
Figure 9 : a. Plasma expansion and laser induced shock wave generation in material. b.
Confined laser-matter interaction.
a)
b)
Plasma
Shockwave
Time
Laser beam
Energy
Water
Target
615
LASER SHOCK ADHESION TEST
-
-
A review of shock adhesion test is given in paragraph “Introduction”. The Laser Shock
Adhesion Test (LASAT) consists in a contactless, automatable adhesion test and can be
implemented in an industrial background (Berthe et al., 2011). This technique relies on
the use of a shock generator, currently a high energy pulsed laser and a laser Doppler
interferometer as a diagnostic tool. For experiments presented in this chapter, several
laser sources were used :
Nd-Glass pulsed laser with a 1055 nm wavelength, a 3 ns pulse duration and 100 Joules
at maximum energy belonging to the Laboratoire pour l’Utilisation des Laser Intenses
(LULI) at Ecole Polytechnique, France. This source has been upgraded to 2000 joules
lately.
at maximum energy, base at Ecole Nationale Supérieure de Mécanique et
d’Aérotechnique (ENSMA), France.
at maximum energy is nowadays also based at Ecole Nationale Supérieure de Mécanique
et d’Aérotechnique (ENSMA), France.
Nd-Yag pulsed laser with a 1064 nm wavelength, a 10 ns pulse duration and 2.5 Joules at
maximum energy, which is a table top laser available in the market, based at Ecole
Nationale Supérieure des Arts et Métiers (ENSAM), Paris, France.
The LASAT technique illustrates well the use of the effects of the wave propagation in an
industrial context (Resseguier et al., 2010). Depending on its intensity, the compressive
wave and its consecutive traction wave at the interface of multi-layered targets may
delaminate the material (Bolis et al., 2007). Coupled with a measurement technique and
with an inverse approach using numerical simulation, this technique allows the estimation
of the adhesion strength and has been compared to some conventional methods (Arrigoni
et al., 2006). This method can be implemented in the production pace since it is executed
in quasi real time. This approach needs then to have a good knowledge about the
behavior of the concerned materials under dynamic solicitations in order to have the best
modeling of the wave propagation in the assembly.
Several couple of materials were submitted to the LASAT : plasma-sprayed copper on
aluminium substrate deposited by the PROTAL (PROjection Thermique Assisté par
Laser) method (Barradas, 2004). The PROTAL process is an air plasma-sprayed method
assisted by a laser heating system allowing monitoring the heating temperature of the
substrate during the spraying stage. The Sprayed copper / aluminium substrate is of a
high interest for observing the influence of intermetallic phases on the adhesion level.
Cold Sprayed copper deposited on aluminium substrate was also studied (Barradas,
2005). The authors could compare the influence of the spraying method on the adhesion
of a copper coating on its aluminium substrate. They also could determine the
interlamellar strength of the coating. Materials presented in figure 1 have also been
submitted to the LASAT process. Recently, the LASAT process could evidence the
difference of bond strength within a composite assembly (Gay et al., 2011). The
matrix/fiber interface was disbanded as well as the interface between two plies.
Experimental Set-Up
As said in section “Laser induced shock wave”, the shock generation depends on the
irradiated material and the surrounding medium. Several variants of the LASAT
technique have been tested.
616
Direct Irradiation. The first configuration is the irradiation in vacuum condition (fig.
10.a). This situation allows generating extremely intense pressure but a thorough vacuum
and a powerful laser source are required, which is not reasonable for an industrial use.
Figure 10: Variants of the LASAT Technique on a coated sample.
e)
b)
c) Shock generation d)
a)
Water
L.I.M.
Vacuum
f)
flyer
Shock detection by laser Doppler Interferometer
The technique meets some limitations due to the shock attenuation during its propagation
in the thickness of the sample (see subsection “hydrodynamic decay”). Indeed, the use of
high energy pulsed laser, in order to generate shock waves, reduces the application of the
debonding test to systems within the millimetric range in term of sample thickness.
Thereby, other techniques are explored in order to overcome to this limitation.
Shock On Coatings. This configuration (fig. 10.b) has been tested for both configurations
Zsubstrate > Zcoating and Zsubstrate < Zcoating (Arrigoni et al. 2006b) with 250 µm of aluminium
plasma-sprayed onto 5 mm of copper and 250 µm of tantalum deposited onto 5 mm of
steel. The suitable configuration expected by the analytical approach is the one with 250
µm aluminium on 5 mm of copper, Zsubstrate > Zcoating. Besides, the smaller the impedance
ratio, the higher tensile stress, but still limited to twice the incident shock pressure
amplitude. Even though this technique does not satisfy both configurations, it brings a
huge advance in term of thickness accessibility (up to 5 mm).
Confined Regime. Another configuration has been experimented. It involves a confining
layer, such as water or glass; few tens of microns are suitable, but not more because of
the energy absorbance of the infrared wavelength by the water (fig. 10.c). This is the best
ratio pressure max versus price. Laser sources available in the market can be used in this
situation (Nd-YAG laser able to provide at least 2 joules in 10 ns with a 1.064 µm
wavelength for sensing a 10 mm² area).
Low Impedance Material. A fourth configuration has been explored (fig. 10.d). It
consists in adding a low impedance material behind the irradiated area. The impedance
mismatch will increase the maximum of pressure (Arrigoni et al. 2003). Experiments
carried out on a 90 µm Copper substrates coated with 110 µm of Chromium,
electrodeposited, showed that with 20% less density of power, pressure was 50% higher
(fig. 11.a). An inverse approach, based on the fit of free surface velocity measured with
VISAR, was performed with the hydrocode SHYLAC, a monodimensional, finite
difference explicit code from ENSMA (fig. 11.b). It allowed the determination of the
tensile stress at the Cr/Cu interface; it was respectively 26 and 17 kbar, respectively with
and without low impedance material in the loaded face. Despite of its interest, the LIM
method is still limited to samples of about few hundred microns thick because of the
hydrodynamic decay.
Flyer Laser Accelerated Shock Adhesion Test. A fifth configuration (fig. 10.e) has been
successfully prospected (Boustie et al. 2005). The F-LASAT consists in accelerating a
flyer intended to impact the sample. Thus, the shock impulse generated depends on the
617
flyer velocity, the nature of its material and of its thickness. By choosing an adapted flyer
material and thickness and terminal velocity, it is possible to optimize the tensile stress
provoked at the interface.
Figure 11 : a. bond strength of 110 µm electrodeposited chromium on 90 µm copper with
(lozenge) and without (circle) law impedance material. b. Inverse approach on the free
surface velocity – dashed line, simulation – full line, VISAR records; the highest
amplitude is the shot with LIM (20 kbar) other is without LIM (26 kbar).
a)
b)
Figure 12.a shows the comparison of tensile stress at the interface, computed with
SHYLAC for a given laser energy equivalent to a Gaussian pulse of pressure of 6.5 GPa
at full height and 30 ns of duration at half maximum. The first calculation was made with
the Gaussian like pressure (dashed line). The second calculation was performed with a
618
100 µm thick aluminium flyer impacting the sample at 800 m/s (dot line). The third
calculation was run with a 480 µm thick aluminium flyer impacting at 500 m/s (full line).
Both flyer velocities are terminal velocities of the flyer propelled with the same energy
involved in the Gaussian pulse. In the thicker flyer, the release waves from the unloading
cross the release waves from the reflection at the free surface exactly at the interface. In
the two other cases, the tensile stress appears first in the coating, what can damage it
before or instead of the interface and makes the diagnosis more difficult. In bother flyer
configuration, the available tensile stress at the interface is three to four times higher than
the one obtained in confined regime (Gaussian) and is maintained a longer time, which
makes a huge difference in cumulative model. Figure 12.b shows a 3000 µm thick
aluminium substrate plasma sprayed with 300 µm copper and a 5000 µm thick
aluminium substrate samples coated with 200 µm of Ni-Steel alloy, debonded with the FLASAT method. Despite of the fact that this method reminds more difficult to automated,
it allows opening the LASAT test to thick samples.
Figure 12 : a. Comparison of tensile strength at the interface of a 3000 µm aluminium
substrate coated with 300 µm of copper. b. Cross section of samples recovered, submitted
to F-LASAT experiments (Al 5000 µm / Ni-Steel alloy 300 µm and Al 3000 µm / Cu 300
µm).
a)
b)
Edges Laser Adhesion Test. At last, a recent technique consists in applying the edge
effects (fig. 10.f) to produce damage at the interface (Boustie et al., 2007). Figure 13
shows mechanisms of traction generation by edge effects. When the diameter of the
619
shocked area is lower than 2 times the sample thickness, the propagation of release waves
in the wake of the shock front is marked. They follow toric propagation so they will cross
each other while propagating towards the median axis of the loading path. By crossing
each other, they will provoke a zone of traction propagating after the shock front.
Reflected release waves at the free surface will interact with this traction wave and
provoke even more traction, which is likely favorable to spallation, especially for thin
film coatings (Cuq-Lelandais, 2010). This phenomenon experimentally observed (fig.
13.b) were reproducible by numerical simulation, with the dynamic explicit finite
element commercial code RADIOSS© (In ALTAIR HYPERWORKS suite V.10) (fig.
13.c). The Tuler-Butcher criterion was included in the model (see subsection “some
damage models”) and it gave acceptable results that confirm the presented analysis in
term of history of wave interactions. In the color scale, tensile stress is represented in
blue and compression in yellow.
Figure 13 : a. Description of spallation by edge effects. b. experimental observation of
edge effects on aluminium. c. Simulation with RADIOSS© of damage with the TulerButcher criterion.
c)
Loading
a)
b)
200 µm
Release waves
Shock front
Axial traction wave
In 2001, the LASAT technique was hardly able to evaluate the bond strength of
millimeter samples. Nowadays, the technique has made progress and is extended to
thicker samples (> 5 mm).
EFFECT OF THE INTERFACE TOPOLOGY
Another appreciable progress is the ability of doing local evaluation of adhesion. The
LASAT technique allowed the discrimination of plasma-sprayed parameters, in the case
of copper plasma sprayed on aluminium, like the pre-heating temperature (the substrate
temperature), the nature of the propulsion gas, the surface roughness … (Barradas et al.,
2004, 2005). Indeed, Inert Plasma Spraying (IPS) gave better results compared with Air
Plasma Spraying (APS) because in the case of IPS, sprayed particles are not oxidized by
air and don’t create intermetallic phases that make interface brittle. Intermetallic phases
are also favored by elevated pre heating spraying temperature (> 265 °C). However,
lower temperature (< 220 °C) inhibits the wetting allowing the copper to match with the
substrate roughness. A too smooth substrate roughness (Ra < 4 µm) also inhibit the
mechanical anchorage as well as too important roughness (Ra > 8 µm) because it will
multiply pre-existing cracks due to difficulties to clean correctly the substrate surface.
Between these two limits, the adhesion increases with the roughness (Siegmann et al.,
1999; Arrigoni, 2010). A simulation by finite element with the code RADIOSS© also
helped to explain the crack location in the case of a calibrated roughness, obtained by
milling (Fig. 14). The origin of this concentration of traction is due to the crossing of
oblique traction waves occurring on the longer slope of the roughness.
Figure 14 : Cross section of a recovered sample of 470 µm of aluminium,
plasma sprayed with 300 µm of copper. The interface before spraying was
620
obtained by milling . Corresponding numerical simulation with RADIOSS©,
traction is in blue.
20 µm
Traction max.
spall
APPLICATION TO ADHESIVELY BONDED MATERIALS
Sprayed and electrodeposited coatings presented until here are off course widely spread
and it was shown that the LASAT technique is one of the suitable tests for evaluating the
interfacial bond strength. But LASAT can also be applied to adhesively bonded
assemblies also largely used in Industry, especially in the aeronautical industry, for which
a defect in the structural adhesive has to be perfect (Bossi et al., 2005).
Metallic Assemblies With Structural Adhesive
The LASAT technique has been applied to metallic plates adhesively bonded with
structural adhesives (Arrigoni et al, 2008; Radhakrishnan et al., 2008; Laporte et al,
2009). Various structural adhesives have been tested, among them, the epoxy glue
FM1000© glue manufactured by CYNANAMID©. Aluminium plates of respective
thickness of 410 µm and 500 µm were adhesively bonded. LASAT shots have been
performed at the Institute for Industrial Materials (IMI) of the National Research Council
of Canada (NRCC), Boucherville, Quebec. The energy source was a commercial laser
able to provide 2 joules at 1064 nm during 10 ns. Shots were performed at different
places of the sample, in a circle of 3 mm of diameter and far from the borders, with
densities of power of successively 0.67, 1.44, 2.47, 3.69, 4.69, 5.71, 6.45 and 6.77
GW/cm². The free surface velocity was recorded for each shot and then analyzed. The
diagnosis becomes complicate because of the existence of several layers of different
acoustic impedances (fig. 15). There were a multitude of rebounds coming out at the free
surface and having effects on its particle velocity (fig. 16.a). However, by performing a
Fast Fourier Transformation (FFT), it was possible to determine what the main
frequencies were and then to get an information about the integrity of the sample. The
FFT of the shot at 4.69 GW/cm² exhibits less peaks than the one at lower density of
power (fig. 16.b) . It reveals that some rebounds do not occur in the shot at highest
density of power, that is to say, there is a spall in the sample. Shots were aligned so that it
was possible to perform an extra diagnostic under laser ultrasonic inspection with the
same experimental setup, along the shot alignment (BScan). From particle velocities of
the free surface, it was possible to rebuild the stress history by inverse approach based on
SHYLAC simulations, around the delamination threshold. The bond strength was
estimated between 278 and 378 MPa.
621
Figure 15 : a. Layout of LASAT technique applied to adhesively bonded aluminium
plates. b. Space-time diagram showing the spallation at interface. c. Recovered sample.
3
2
4
1
P
sensing
0
x
Plate 1 Adhes. Plate 2
Impacted area
FM1000
6
5
Al 410 µm
7
t
Cohesive rupture
cohésive
Adhesive rupture
adhésive
Al 500 µm
shock
Figure 16 : a. Free surface velocity records for shots at 2.47 and 4.69 GW/cm²
respectively in full and dashed line. b. Fast Fourier Transformation of velocity records, in
arbitrary unit. c. Adhesion threshold of the FM1000 with BScan inspection.
BScan
622
It is shown that the LASAT technique can be applied to adhesively bond metallic plates.
However, the diagnostic becomes delicate, especially in case of cohesive rupture (fig.
15.c).
Application To Composites
Lately, the LASAT method has been transposed to a Shock Adhesion Test on Adhesively
bonded Composite (SATAC) (Bossi et al., 2009). Perton et al. (2011) performed shots on
carbon fiber epoxy samples made of adhesively bonded composite plates, in water
confined regime with a commercial laser source (2 J, 10 ns, 1064 nm) at IMI-NRCC.
Composite plates were either made of four plies pre-impregnated with epoxy Cytec 52761, with [0/90]s orientation, or eight plies with [0/45/90/-45]s orientation. Composite
plates were adhesively assembled with glue EA9394 of Hysol®. They could obtain a
damage threshold of 150 MPa at the interface of a four plies-four plies assembly (noted
4/4), 140 MPA for the 4/8 and 150 MPa for the 8/8. Plies thickness varies from 160 to
180 µm. They could also evaluate the inter-ply bond strength at 340 MPa. All
delaminations were diagnosed by CScan.
Gay, 2011 have presented experimental results obtained on the same type of composites,
with higher energy laser sources that allowed testing of thicker assemblies and also the
inter-fiber spallation (fig. 17.a), inter-ply spallation (fig. 17.b) and inter-plate spallation
(fig. 17.c). Diagnostics were made by cross-section observation and micro tomography.
Figure 17 : a. inter-fibre spallation. b. inter-ply spallation at 8th ply on 8 plies [0/45/90/45]s obtained in water confined regime. c. inter-plate spallation
a)
b)
c)
SHOCK WAVE PROPAGATION IN POROUS MATERIALS
Plasma sprayed coatings have been mentioned quite few times in this chapter.
Intrinsically, due to the agglomerate of liquefied grain of powder, the constituted plasmasprayed coating has a non negligible porosity. Moreover, the porosity can affect strongly
wave propagation. As the LASAT technique is based on wave propagation analysis for
diagnose and evaluate bond strength, it is important to estimate and model the effects of
the porosity on the test.
623
Effects Of Porosity In LASAT
Effects of porosity have been evidenced during LASAT experiments carried out on
plasma sprayed copper (Arrigoni et al., 2008b). They have a strong diffusive effect and
diminish the sound velocity in the affected material. Figure 18 shows a plasma-sprayed
copper of 420 µm of thickness and corresponding VISAR signals that have been recorded
for shock at 81 GW/cm² in vacuum. The initial porosity was estimated at around 14% by
weighting and cross section analysis. VISAR records where compared with records
obtained on massive copper in weaker shock condition, at 57 GW/cm². Although, the
massive copper was shot at lower energy, peaks of free surface velocity are higher and
narrower, pointing out the strong damping effects occurring in the plasma sprayed
copper. In addition, some pores have a comparable size to the VISAR sensed point. So a
variation in the reproducibility was observed, explained by the presence of pores behind
the sensed point of the free surface velocity.
420 µm
Figure 18 : a. Cross section of plasma-sprayed copper. b. VISAR records comparing
plasma sprayed copper at 81 GW/cm² with massive copper at 51 GW/cm².
Global Model For Porous Materials
Being awards of damping effects of plasma sprayed materials evidenced in LASAT
experiments, a model of global porosity was implemented in SHYLAC and RADIOSS©
in order to enhance inverse approaches. It is based on the P-α model of Hermann, 1969,
that describes the evolution of the porosity α during a period of compaction by
hydrodynamic pressure P (fig. 19.a). The porosity is treated as global by the way of the
hollow sphere approach (Carroll and Holt, 1972;1973) that considers all pores gathered in
one centered in matrix. The matrix behaves like the massive material. Below the elastic
limit Pe, the compaction is reversible. Once the limit exceeded, the compaction process
starts slowly and accelerates while the pressure increases, until reaching a critical
pressure Pc for which porous material behaves like massive one. Hermann gave two
624
expressions for this description; one is exponential (17) and the other polynomial.
Resseguier (2001) enhanced the polynomial expression for sintered steel (18).
α = 1+(αe -1)e-â(P-Pe)
(17)
α =α0-3(α0-1)
+2(α0-1)
(18)
with α0 the initial porosity and â an adjustable parameter.
A more developed approach is given by Arrigoni et al. (2007) and allows better fitting.
On the basis of equation (17-18), the compaction law was implemented in SHYLAC and
RADIOSS©. VISAR signal obtained on 420 µm thick plasma-sprayed copper shocked at
1.7 GPa with Gaussian pulse of 14 ns is compared with numerical simulation of : first,
massive copper governed by perfect elasto-plastic behavior; second, porous copper of 14
% porosity, with polynomial model (18) with Pc = 50 kBar and Pe=0.1 kBar (fig. 19.b).
Velocity peak given by the polynomial model fits fairly well with VISAR record, which
is not the case of simulation with massive copper.
Pc
Compaction regime
Pe
Elastic regime
P
Massive regime
Figure 19 : a. P-α model. b. Simulation with P-α model implemented in RADIOSS©.
α
1
αe
α0
COMPARISON WITH OTHER TESTS
625
Bond strength evaluated with laser shock adhesion tests do not match with the order of
magnitude of other tests. Indeed, bond strength values are of few hundred MPa while it is
rather less than 100 MPa with the bond pull test for example. There are multiple reasons.
First, the LASAT test is a dynamic technique so for producing a damage, it requires more
stress since the application time is shorter. Then, in the LASAT test, there are, a priori, no
existing cracks, so the energy that have to be brought is the addition of the crack
initiation energy and the crack propagation energy. Only few comparative studies are
presented in the literature.
Thermo-Elastic Regime
Rosa et al., 2002, compared the laser adhesion test in thermo-elastic regime with
maximum energy not higher than 50 mJ (in this configuration, terminology “shock wave”
would not be used). The shot was applied at the interface of ceramic coating, plasmasprayed on steel, since ceramic is partially transparent to the laser wave length at 1064
nm. They compared results about the bond strength evaluation of 15 MPa with the value
of 20 to 50 MPa proposed by Amada et al. (1996) and Suga et al. (1992). Rosa et al also
determined stress intensity factor KIC of 0.3 MPa.m1/2 while the bending test performed
by Evans (1974) was of 0.3 to 0.7 MPa.m1/2 and the Double Cantilever Beam test (DCB)
operated by Berndt (1980) gave 0.7 MPa.m1/2. At last they estimated strain energy release
rate GIC of 2.86 J/cm² while DCB gave 12 J/cm² and 2.98 ±0.19 J/cm² for bending test.
Values proposed by Rosa et al were not far from other tests.
-
-
Comparison With Pull Test And Bulge-And-Blister Test
Arrigoni et al. 2006 proposed a comparative study lead in order to situate the LASAT test
among other tests. Concurrent tests retained were :
The bond pull test (ASTM C633), because it is supposed to involve monodimensional
tensile stress (in mode I), like the LASAT test. Moreover, it is a global test that measure
bond strength averaged at the interface, while the LASAT test is rather local. At last, it
also measure initiation plus propagation energy.
The bulge and blister test, because it involves mixed modes, the crack is supposed to be
already initiated. The estimated adhesion is between local and global.
Sample preparation. Coating of 550 µm of copper (METCO 55, – 90 + 45 µm) was
plasma-sprayed on AU4G (AFNOR) or Al 2017 (ASTM). Four series of sample were
made by Air Plasma Spraying (APS) and one by Inert Plasma Spraying (IPS). Various
pre-heating temperatures were used for APS samples : 228 and 255 °C for two APS, at
Ra=0.1 µm – respectively noted APS L 228 and APS L 255; one APS at 255 °C and
Ra=5.15 µm, noted APS S 255 and one IPS at 215 °C and Ra=0.1 µm, noted IPS L 215.
Test Results. Despite of differences between tests, they all determined samples the same
ranking (fig. 20). APS L 228 and APS S 255 could not be tested with bulge and blister
test because of a lack of sample. The highest bond strength was attributed to APS S 255
because of a good mechanical anchoring given by its elevated Ra (5.15 µm), in addition
to a good wettability during plasma-spraying because the pre-heating temperature was of
255 °C. If elevated temperature enhances the adhesion level, IPS 215 showed a stronger
interface than APS S 228. This is due to elevated intermetallics rate formed by oxides
with APS, while there are few intermetallics with IPS.
626
Figure 20 : Results of comparisons between LASAT, bond-pull test and bulge-and-blister
test.
CONCLUSIONS
Being a part of a book tackling the matter of “wave propagation”, the present chapter has
exposed a basic approach of shock physics applied to an industrial application : laser
shock adhesion test. Indeed it has been shown that this application find its existence in
the study of wave propagation and its consequences.
This chapter has proposed an open technical review of shock adhesion tests introduced by
a short history from Vossen (1978) in the U.S.A. until recent progress made on composite
assemblies. This technique has followed an international emergenace and sources of
research have born everywhere in the world, in Industry (Bossi at Boeing) as well as in
laboratories (Pr. Gupta at U.C.L.A, Pr. Sottos at Urbana Champaign, Dr. Boustie at
E.N.S.M.A., Dr. Monchalin at I.M.I., Dr. Oltra at Université de Bourgogne, Dr. Youtsos
in Greece, Dr. Baumung at Karlshrue technical university, …).
Limitations of the use of this technique are falling years after years thanks to efforts
developed by this “community” of researchers and engineers and nowadays this testing
method is becoming accessible to Industry.
As a consequence, this method is of a growing interest and is appearing in recent research
books (Lacombe, 2006; Da Silva, 2011), at least two devices are patented (Pr. Gupta
Vigay and Sokol, D.W.) and the laser shock adhesion test is being transferred in Industry.
The potential use is considerable, in the automotive industry as well as in aerospatial,
aeronautical, microelectronics and semiconductors, optical coatings, medical industry …
Concerning our thirteen years of research dedicated to this technique, we have
summarized in this chapter what we thought as being main advances :
627
-
Understanding the physics of the phenomenon. It required to focus our interest in laser
induced shock waves, laser matter interaction, laser Doppler interferometry, dynamic
behavior and fracture, …
Overcome the decay in order to test thicker samples by various configurations presented
here (shock on coated side, F-LASAT, L.I.M method, Edge Effects).
Understanding and modeling shock propagation in plasma-sprayed coatings. It allowed
us to develop a predictive tool for quantifying the interfacial bond strength.
Comparing the method with other tests in order to determine the adhesion energy.
ACKNOWLEDGEMENTS
Authors would like to acknowledge the French Ministry of Educational, Research and
Technology for supporting our researches in particular the LASAT and SATAC projects.
Authors would also like to thanks technical staff of IMI, ENSMA, Arts et Metiers
ParisTech, LULI, SIMAPS, C2P EVRY.
REFERENCES
Amada, S., and Yamada, H., Surf. Coat. Technol. 78, 50, (1996).
Anderholm, N. C., Applied Physics Letters, vol. 16, p 113, (1970).
Antoun T., Seaman L., Curan D. R., Kanel G. I., Razorenov S. V. and Utkin A. V., “Spall
Fracture” (New York: Springer), (2003).
Arrigoni M. et al., « Benefits of the impedance mismatch technique for LAser Shock
Adhesion Test (LASAT) », Proceedings of the 13th American Physical Society Topical
Conference on Shock Compression of Condensed Matter, Portland, (2003).
Arrigoni M., Barradas S., Bracini M., Dupeux M., Jeandin M., Boustie M., Bolis C., and
Berthe L., « A comparative study of three adhesion tests (EN 582, similar to ASTM
C633, LASAT (LASer Adhesion Test), and bulge and blister test) performed on plasma
sprayed copper deposited on aluminium 2017 substrates », J. Adhesion Sci. Technol.,
Vol. 20, No. 5, p. 471–487, (2006).
Arrigoni, M., Boustie, M., Bolis, C., Berthe, L., Barradas, S., Jeandin, M., "Evolutions of
the LASer Adhesion Test (LASAT) for the debonding of coatings on substrates above the
millimeter range thickness ". Journal de Physique IV, vol 134, p. 739, (2006b).
Arrigoni, M., Boustie, M., de Resseguier, T., Pons, F., He, H. L., Seaman, L., Bolis, C.,
Bolis C., Berthe L., Boustie M., Arrigoni M., Barradas S. and Jeandin M., “Physical
approach to adhesion testing using laser-driven shock waves”, J. Phys. D: Appl. Phys. 40
p. 3155–3163, (2007).
Berthe, L., Barradas, S., Jeandin, M., « The use of a macroscopic model for describing
the effects of porosity on shock wave propagation » J. of appl. Phys. Vol. 101, issue 7
(2007).
Arrigoni, M., Kruger, S. E., Blouin, A., Levesque, D., Lord, M., Monchalin J.-P., « The
Use of Laser-Doppler Interferometry Based on a Fabry-Perot Etalon for Shock Adhesion
628
Test Applied to Adhesively Bonded Materials » 1st international symposium on Laser
Ultrasonics 2008, 16-18th july, Montréal, QC, Canada (2008).
Arrigoni, M., Boustie, M., Bolis, C., Berthe, L., Barradas, S., Jeandin, M., “The use of a
macroscopic model describing the effects of dynamic compaction and porosity on plasma
sprayed copper”, J. of appl. Phys. Vol. 103, issue 8 (2008b).
Arrigoni M., Monchalin J.-P., Blouin A., Kruger S. E., Lord M., “Laser Doppler
Interferometer based on a solid Fabry-Perot Etalon for measurement of surface velocity
in shock experiments”, Measurement Science & Technology 20, 1, (2009).
Arrigoni M., “Propagation des chocs dans les systèmes revêtus », Editions Universitaires
Européennes, (2010) (in french).
Askaryon, G. A., and Morez, E. M., JETP Letters, vol 16, p. 1638 (1963).
Auroux, E., Boustie, M., Romain, J.P., Bertheau, D., Peyre, P., Berthe, L., Bartnicki, E.,
“Debonding study of Ni-base substrate_Pt coatings interfaces using laser shock waves:
characterization of the targets and experimental study”, Surface and Coatings Technology
138, p. 269-277, (2001).
Barbezat, G., International Journal of Automotive Technology, Vol. 2, No. 2, p. 47-52
(2001).
Barker L. M., Hollenbach, R.E., “Laser Interferometer for Measuring High Velocities of
Any Reflecting Surface”, Journal of Applied Physics, vol. 43 (11) : p. 4669-4675, (1972).
Barradas, S., Jeandin, M., Bolis, C., Berthe, L., Arrigoni, M., Boustie, M., and Barbezat
G., « Study of adhesion of PROTAL® Copper Coating of Al 2017 Using the LAser
Shock Adhesion Test (LASAT) » Journal of Materials Science n°39 p. 2707-2716,
(2004).
Barradas, S., Molins, R., Jeandin, M., Arrigoni, M., Boustie, M., Bolis, C., Berthe L., and
Ducos, M., « Application of laser shock adhesion testing (LASAT) to the study of the
interlamellar strength and coating-substrate adhesion in cold-sprayed copper coating of
aluminum » Surface and Coatings Technology, Vol. 197, Issue 1, Pages 18-27, (2005).
Baumung, K., Muller, G., Singer, J., Kanel, G.I., Razorenov, S.V., “Strength of plasma
sprayed turbine-blade coatings using an advanced spallation technique », J. Appl. Phys.,
Vol. 89, No. 11, (2001).
Berndt, C. C., Ph.D. thesis, Monash University, Clayton, Victoria, Australia, (1980).
Berthe, L., Arrigoni, M., Boustie, M., Cuq-Lelandais, J.-P., Broussilliou, C., Fabre, G.,
Jeandin, M., Guipont, V., Nivard, M. “State-of-the-art laser adhesion test (LASAT)”,
Nondestructive Testing and Evaluation, DOI:10.1080/10589759.2011.573550, (2011).
Berthe, L.; Fabbro, R.; Peyre, P.; et al., “Shock waves from a water-confined lasergenerated plasma”, Journal of Applied Physics, Vol. 82 Issue: 6 p. 2826-2832, (1997).
Bolis C., Berthe L., Boustie M., Arrigoni M., Barradas S. and Jeandin M., “Physical
approach to adhesion testing using laser-driven shock waves”, J. Phys. D: Appl. Phys. 40
p. 3155–3163, (2007).
Bossi, R., Housen K. and Walters, C., « Laser Bond Inspection Device for Composites:
Has The Holy Grail Been Found? » Nondestructive Testing Information Analysis Center
Newsletter Volume 30, No. 2, (2005).
629
Bossi, R., Housen, K., Walters, C. T. and Sokol, D., “Laser bond testing” Mater. Eval. 67
p. 819–_27, (2009).
Boustie, M., Auroux, E., Romain J.-P., Manesse, D., Bertoli, A., “Determination of the
bond strength of some microns coatings using laser shocks”, Eur. Phys. J. AP. 5, p. 149,
(1999).
Boustie, M., Arrigoni, M., Berthe, L., Bolis, C., Jeandin, M., Barradas, S., « Optimization
of the debonding test by impact of laser accelerated metallic foils on coating/substrate
systems », SMT 19, 1-3 aout 2005, St Paul, Minnesota, USA, (2005).
Boustie, M., Cuq-Lelandais, J.-P., Bolis, C., Berthe, L., Barradas, S., Arrigoni, M., de
Resseguier, T., Jeandin, M., « Study of damage phenomena induced by edge effects into
materials under laser driven shocks”, J. Phys. D: Appl. Phys., vol. 40 p. 7103 (2007).
Cuq-Lelandais, J.-P., “Etude du comportement dynamique de matériaux sous choc laser
subpicoseconde », Ph.D Thesis, ENSMA, (2010) (in french).
Carroll, M.M., Holt, A.C, “Steady waves in ductile porous solids”, Journal of Applied
Physics, 1973, 44,10, p. 4388-4392, (1973).
Carroll M.M., Holt A.C., “Suggested modification of the P-α model for porous
materials”, Journal of Applied Physics, 43, 2, p. 759-762, (1972).
Chalker P.R., Bull S.J. and Rickerby D.S., “A review of the methods for the evaluation of
coating-substrate adhesion”, Materials Science and Engineering, vol. 40, p. 583-592,
(1991).
Clauer, A. H., Holbrook, J. H., Fairand, B. P., “effects of laser induced shock waves on
metals” in “Shock waves and high-strin-rate phenomena in metals” edited by Meyers,
M.-A. and Murr, L. E., plenum publishing corporation, (1981).
Da Silva, L.F.M, Ochsner, A., Adams, R.D., “Handbook of adhesion technology : Vol.1,
Vol. 2”, Springer edition, (2011).
Davison, L., “Fundamentals of shock waves in solids”, editions Springer Verlag, (2008).
De Resseguier T., Romain J.-P., "Investigation of the response of a porous steel to laser
driven shocks", Shock waves, Springer Verlag, 11, p 125-132, (2001).
De Rességuier T., Cuq-Lelandais J.-P., Boustie M., Lescoute E., and Berthe L., “Wave
Propagation in Materials for Modern Applications”, edited by: Andrey Petrin, ISBN
978-953-7619-65-7, p. 526, INTECH, (2010).
Dupré A. , Théorie mécanique de la chaleur, Paris, Gauthier-Villars, p. 368, (1869).
Epishin I.G., Suslov V.V., and Yanushkevich V.A.,“Determination of adhesion strengh
of film structures of components in electronic devices using laser shock waves”, Fizika i
Khimiya Obrabovki Materialov, vol. 22, (5), p. 80-84, (1988).
Evans, A. G., in Fracture Mechanics Determinations, Fracture Mechanics of Ceramics,
edited by R. C. Bradt, D. P. H. Haselman, and F. F. Lange, Plenum, New York, Vol. 1, p.
17, (1974).
630
Fabbro R., Faral B., Virmont J., Cottet F., Romain J.P., Pépin H., “Experimental study of
ablation pressures and target velocities obtained in 0.26 µm wavelength laser experiments
in planar geometry”, Physics fluids, vol. 28, n°11, p. 3414-3423, (1985).
Garban-Labaune C., Thèse d'Etat, Université de Paris XI, (1982) (in french).
Gay, E., Ph.D. Thesis, Arts et Metiers ParisTech, (2011).
Guipont, V., Jeandin, M., Bansard, S., Khor, K. A., Nivard, M., Berthe, L., CuqLelandais, J.-P. and Boustie, M., “Bond strength determination of hydroxyapatite
coatings on Ti-6Al-4V substrates using the LAser Shock Adhesion Test (LASAT)” J.
Biomed. Mater. Res., 95A: p. 1096–1104. doi: 10.1002/jbm.a.32907, (2010).
Gupta, V., Argon, A. S., Parks, D. M. and Cornie, J. A., J. Mech. Phys., Solids 40, p.
141, (1992).
Gupta V., “System and method for measuring the interface tensile strength of planar
interfaces”, US PATENT N°5 438 402, (1995).
Gupta, V. Kireev, V., Tian, J., Yoshida, H., Akahoshi, H., “Glass-modified stress waves
for adhesion measurement of ultra thin films for device applications », J. Mech. Phys.
Solids 51, p. 1395 – 1412, (2003).
Grün J., Decoste R., Ripin B.H., Gardner J., Applied physics letter, 39, 7, p. 545, (1981).
Herrmann, W. J. Appl. Phys. 40, p. 2490, (1969).
Johnson, G.R., and Cook, W.H., “A Constitutive Model and Data for Metals Subjected to
Large Strains,High Rates and High Temperatures,” Proceedings of the Seventh
International Symposium on Ballistics ,The Netherlands,The Hague, p.541-547, (1983).
Kanel, G.I., Fortov, V.E., Adv. Mech., 10, (3), (1987).
Kobayashi, A., Jain, A., Gupta, V., Kireev, V., “Study on the interface strength of
zirconia coatings by a laser spallation technique”, Vacuum 73, p. 533–539, (2004).
Lacombe, R., Adhesion Measurement Methods, edited by CRC Taylor and Francis,
(2006).
Laporte, D., Malaise, F., Boustie, M., Chevalier, J.-M., Buzaud, E., « Response of
bonded assemblies under shock wave loading », DYMAT 2009 Proc., Bruxelles (2009).
Loh, R.L., Rossington, C., Evans, A.G., J. Am. Ceram. Soc. 69, p. 139, (1986).
Meyers, M. A., “Dynamic behavior of materials”, John Wiley and sons, (1996).
Monchalin, J.-P., Héron, R., Bouchard P., Padioleau, C., Applied Physics Letters, 55 (16),
(1989).
Monchalin, J.-P., “Laser ultrasonics : From the laboratory to industry”, Keynote
presentation at the Review of Progress in Quantitative Nondestructive Evaluation, Green
Bay, Wisconsin, July 27th-August 1st, 2003, AIP Conference proceedings, eds, D. O.
Thompson and D. E. Chimenti, vol 23A, p. 3-31, (2004).
631
Perton, M., Blouin, A. and Monchalin, J.-P., “Adhesive bond testing of carbon–epoxy
composites by laser shockwave”, J. Phys. D: Appl. Phys. 44, 034012, 12p, (2011).
Phipps C. R, Turner et al, "Impulse coupling of targets in vacuum by KRF, HF and CO2
single pulse lasers", Journal of Applied Physics, 64 ,3, p. 1083, (1988).
Radhakrishnan, J., Boustie, M., Berthe, L., Arrigoni, M., «Interfacial strength
measurement of bonded aluminium foils by laser-driven shock waves”, 22nd Conference
on Surface Modification Technologies, 22-24 sept. 2008, Trollhätten, Swede, (2008).
Rosa, G. Oltra, R., Nadal, M.-H., “Evaluation of the coating–substrate adhesion by laserultrasonics: Modeling and experiments », J. Appl. Phys., Vol. 91, No. 10, 15, (2002).
Scruby, C. B., Dewhurst, R. J., Hutchins, D. A., and Palmer, S. B., J. Appl. Phys. 51, p.
6210, (1980).
Siegmann S., Brown C. A., “Surface Texture Correlations with Tensile Adhesive
Strength of Thermally Sprayed Coatings Using Area-Scale Fractal Analysis”, 2nd United
Thermal Spray Conference, Düsseldorf, D, p. 355-360, (1999).
Sokol, D.W, Walters, C. T., Dulanay, J. L., Toller, S. M., “Laser system and method for
non-destructive bond detection and evaluation”, US PATENT n°US2005/0120803A1, 9
(2005).
Sollier, A.; Berthe, L.; Fabbro, R., “Numerical modeling of the transmission of
breakdown plasma generated in water during laser shock processing”, European Physical
Journal-Applied Physics Vol.16 Issue: 2 p. 131-139, (2001).
Steinberg D.J., Cochran, S.G., and Guinan, M.W., "A Constitutive-Model for Metals
Applicable at High-strain Rate," Journal of Applied Physics, 51, 3, p. 1498–1504, (1980).
Suga, Y., Harjanto, Y., and Takahashi, J., in Thermal Spray: International Advances in
Coatings Technology, edited by C. C. Berndt, ASM International, p. 247, (1992).
Tang, C., Zhu, J., “The measurement of interface strength of TiN coating/substrate by
laser spallation”, Int. J. Refract. Hard Metals 14, p. 203-206, (1996).
Tattersall, H.G., “The ultrasonic pulse-echo technique as applied to adhesion testing”, J.
Phys. D: Applied Physics, volume 6, p. 819-832, (1973).
Thouvenin, J., “Détonique”, editions Eyrolles CEA, (in French), (1996).
Trainor R.J., Graboske H.C, Long K.S, Shaner J.W, "Application of high power lasers to
equation of state research at ultra-high pressures", Lawrence Livermore Laboratory,
UCRL-52562, (1978).
Vossen, J.L, “Measurement of Film-Substrate Bond Strength by Laser Spallation,
Adhesion Measurement of Thin Films, Thick Films, and Bulk Coatings”, ASTM Spec.
Tech. Publ. American Society for Testing and Materials, p. 122-133, (1978).
632
Wang, J., Sottos, N. R., Weaver, R. L. , “Tensile and mixed-mode strength of a thin filmsubstrate interface under laser induced pulse loading“, Journal of the Mechanics and
Physics of Solids, vol. 52, p. 999-1022, (2004).
White, R. M., J. Appl. Phys. 34, p. 3559, (1963).
Youtsos, A.G., Kiriakopoulos, M., Timke, T.,« Experimental and theoretical/numerical
investigations of thin films bonding strength », Theoretical and Applied fracture
Mechanics, vol. 31, p. 47-59, (1999).
Zel’dovich, Ya., Raizer, Yu. “Physics of shock waves and hight temperature
hydrodynamic phenomena”, Academic Press, (1966).
Zerilli, F.J., and Armstrong, R.W., J. of Appl. Phys. 61, p. 1816, (1987).
Zhou, M.,.Zhang, Y.K, Cai, L., “Adhesion measurement of thin films by a modified laser
spallation technique : theoretical analysis and experimental investigation”, Applied
Physics A, vol. 74, p. 475 480, (2002).
633

An Industrial Challenge Based on the Wave

Transcription

Similar documents

Laser Engraving - Source International

Laboratory for Hypersonic and Shock wave Research, IISc

Effect of Eye Tracking on Ablation Profile

Legacy Sell Sheet

Legacy Sell Sheet

the best in service.

Golfland flyer

kss-213c/kss-213q laser assemblies

eXtreme Team Laser Ball

Sell Sheet - Zeitgeist Films