Upload
others
View
10
Download
0
Embed Size (px)
Citation preview
Modern Applied Science; Vol. 15, No. 1; 2021 ISSN 1913-1844 E-ISSN 1913-1852
Published by Canadian Center of Science and Education
32
Identification of 'Defects' in Epoxy Matrix Composites and Carbon Fiber by Ultrasound. Interaction of the Ultrasonic Beam with the
Material Gaston Sanglier1, Eduardo J. Lopez1, Sonia Cesteros1 & Roberto A. Gonzalez1
1 Architecture and Design Department, Engineering Area, Escuela Politécnica Superior, Universidad CEU San Pablo, Montepríncipe Campus, 28668, Boadilla del Monte, Madrid, Spain Correspondence: Gaston Sanglier, Engineering Area, Escuela Politécnica Superior, Universidad CEU San Pablo, Montepríncipe Campus, 28668, Boadilla del Monte, Madrid, Spain. Received: September 2, 2020 Accepted: October 28, 2020 Online Published: December 22, 2020 doi:10.5539/mas.v15n1p32 URL: https://doi.org/10.5539/mas.v15n1p32 Abstract Non-Destructive Testing (NDT) methods, and especially, ultrasounds have gone from being a mere laboratory curiosity to an indispensable tool in the industry as a primary means of determining the level of quality achieved in its products (ASM, 1989; Barbero, 1999). This study will identify and apply the main physical phenomena of interaction of an ultrasonic wave in a composite material, to see if through this type of waves, you can detect defects of the type of porosity or delaminations in these materials. The percentages of reflected and transmitted waves in real cases of defects in the composite material will also be studied. It will be shown if the frequencies and intensities of the waves are adequate to find this type of defects or imperfections in the material. The theoretical study of the ultrasonic wave seeks to help researchers in the development of equipment that uses the methodology of immersion ultrasound for the inspection of materials in the search for 'defects' and to understand the physics of the test. Keywords: ultrasound, carbon fiber, epoxy matrix, porosity, delamination, NDT techniques 1. Introduction In the last decades the operating requirements have increased, while at the same time trying to reduce the weight of the structures and mechanical components used for industrial purposes. This has led to the need to use advanced materials that have high mechanical properties along with a decrease in weight (Inasmet, 1998). The use of fiber reinforced polymeric matrix composites has replaced in many cases conventional materials (steel, plastic, aluminum, concrete, etc.). These materials have been used preferably in the aeronautical and space industry for the manufacture of floor panels, spoilers, rudders, depth rudders, interior and exterior ailerons, space shuttles, satellites, etc. where they have had a greater development because they are structures that require high values of resistance and specific rigidity, and in which the weight factor entails a great decrease in the cost (Sanglier et al., 2003; Ramírez & Col, 1982; Wróbel & Wierzbicki, 2005; Ramírez López et al., 1996). Fiber-reinforced composite materials are also used in other sectors such as construction, wind turbines, marine, elite sports, automotive and other sectors such as medical and military (ImieliÉska et al., 2004; Rojek, Stabik, & Wróbel, 2005; Ochelski, 2004). These composite materials are characterized by high rigidity and mechanical resistance, high fatigue resistance, corrosion resistance, low weight and the possibility of selecting the appropriate orientation of the sheets for each specific application. Their low thermal conductivity and high dimensional stability give these materials a very interesting alternative in applications subject to low temperature conditions. The structural components of this type are made up of plate and/or beam type elements, which are subjected to loads perpendicular to their plane that originate a state of work in bending in which tensile and compressive stresses appear (Padmanabhan & Kishore, 1995; Potel et al., 1998; Scarponi & Briotti, 2000; Vaccaro & Akers, 1996). For example, these tensile states can appear in the aerodynamic loads exerted on the wings of an aircraft.
mas.ccsen
Howeverdefects unthat can chas been resistanceFor all thtechniqueinteractioreflected 2. MethoTo carry and a thirresistancemanufactcured laywide. Sixteen la(test piecin the foufrom the Below arcorresponspecimenAttached three typeinformatidifferenceobservatitype is intamplitude
net.org
r, another aspenderstood as
cause the failuobserved expe to compressihese reasons, e, in this case on of a wave and transmitt
ods out the study
rd with delame carbon fibertured in an aut
yer of 0.13 mm
ayers were usee) of 3mm aft
urth layer (at 0surface, in thee some imagends to the refern with medium
are some imaes of panels anion to capturees in attenuaton conditionstrinsically insee to oscillate.
ect of great imporosity, dela
ure of the mateerimentally thion (Cantwell
it is necessathe ultrasoundwith the comed wave in a d
, several paneminations) of cor AS4 preimprtoclave, curingm with a fiber w
ed, overlappedter the curing p0.75 mm frome central part oes of the specimrence specime
m porosity, andages taken by nalyzed. The ie it in a singltion or travel s (Huang et alensitive and thHowever, des
Figure 1.
Mod
mportance andamination or aerial in case ofhat the delaminet al., 1986; G
ary to know hds, those poss
mposite materidetermined im
els have been omposite materegnated in theg pressure 6 baweight per are
d in a unidirecphase. Each la
m the surface) of the test piecmens used in en (well made d finally, the sultrasound us
image is a verle glance. It mtime, and dig
l., 1998; Mourhe signal detecspite the low s
Different typ
dern Applied Sc
33
d where this staccumulation f receiving impnations produ
Gray et al., 199how to ident
sible defects atial and to be
mperfection or
manufacturederial based one form of unidars, volumetricea of 145 gr/m
ctional way (dayer has a thicand the delamce). the test. The swith no defec
specimen P2 osing total immry powerful inmakes it possgital support turitz, Townsedcted is usuallysensitivity the
pes of specime
cience
tudy is going of material (f
pact loads on tuced by this ty95; Baker, Jonify, using somttending to theable to calcu
r defect.
d (one of refern a modified edirectional tapc fiber content
m2. The size of
direction of theckness of 0.18
minations were
specimen withcts), the specimon the left cor
mersion transmnstrument that sible to easilyechniques allo
d, & Shah Khy quite affectedre is a high de
ens in the ultra
to be centeredfiber cuts, resithe structure o
ype of impact cnes, & Calliname NDT (Noe study of the ulate and inter
rence, anotherepoxy matrix 8e with a curint of 62% and nf the panels wa
e fibre 0º) with75 mm, then t
e made in the
h the letter R imen P1 on the responds to th
mission with 1allows to inte
y compare adjow the technian, 2000; Kind by noise or iefect capacity.
asonic test
Vol. 15, N
d is the identifin, fiber break
of composite mconsiderably r
an, 1985; Bishon-Destructivephysical phen
erpret the perc
r with medium8552 togetherng temperaturenominal thicknas 34 cm high
h a final panelthe porosity weighth layer (
in the lower cright correspo
he delaminatio1 MHz frequeegrate a great jacent areas wician to easilyno, 1979). A tinstability that.
No. 1; 2021
fication of kage, etc.) material. It reduce the
hop, 1985). e Testing) nomena of centage of
m porority r with high e of 180ºC ness of the
h by 29 cm
l thickness was caused (at 1.5 mm
entral part onds to the ons. ncy of the amount of
with small y optimize test of this t causes its
mas.ccsen
Attached specimen
Figure 2.
Figure 2 defects) ofigure 2 (rwith medin red ma
In figure defects hdelaminasizes (3x3test piece
net.org
are some imans.
Reference tes
(left) shows aof the materialright) it is obs
dium porosity harks this circum
3, an ultrasonhave been geations caused b3mm, 5x5mme.
ages taken by u
st tube on the l
an ultrasonic il under study. served an ultrahave been genmstance, in ad
Figure 3. nic inspectionenerated. A kby Teflon bag
m, 7.5x7.5 mm,
Mod
ultrasound usi
left (A) and P1reinfor
inspection usiIt is observed
asonic inspectinerated in the ddition to the u
P2 test tube wn using immerkind of dark gs, application, 9x5 mm 10x
dern Applied Sc
34
ing the 1 MHz
1 test tube withrced with carbing immersionthe unidirectiion using immfourth layer oupper central
with delaminatrsion transmissquares clear
n of release agx10 mm) place
cience
z total immers
h medium poron fiber n transmissionionality of the
mersion transmof the test tube
zone.
tion zones in tssion of the P2rly aligned in
gents, resin stied between lay
sion transmiss
rosity on the ri
n of the referefiber at 0º alon
mission of the tor sample. Es
the sample 2 specimen isn four rows cking, fiber cu
yers have been
Vol. 15, N
sion of the thre
ight (B) of epo
ence specimenong the whole test tube P1 wspecially the l
s shown whereappear. Thesuttings, etc. o
n placed in lay
No. 1; 2021
ee types of
oxy matrix
n (without sample. In
where areas ower zone
e different se defects, f different
yer 8 of the
mas.ccsen
2.1 TheorUltrasounNesvijskilayer) in tThe stabiabsence obetween sbe done a
FigIt will be will occuwave we between 2microscopmoleculeabsorptioal., 1996;Next, som1987; KaWave freall particlAcoustic zone. Thifrequencyliquids anthis influea very use
where E iand axial Acoustic The resisimpedancvibration small chathe wavepressure calculated
net.org
retical Foundand measuremei, 2000; Dunegthe coupling flility of the ouof turbulencestylus nozzle aautomatically
gure 4. Left: wtaken into ac
ur that will be refer to frequ
20 and 100 KHpy. These ults capable of
on and dispersi; Hervfeld & Lme important apranos & Priequency (f): is les and is idenvelocity (C): is velocity is y and any wand gases, on prence can be neeful condition
is the moduludeformationsimpedance (Z
stance that thce, impedanceof the wave.
ange in sound p. If, on the cois high, sinced through the
ations and Coents have beengan & Tetelm
fluid, which is utput signal is. The design and sample is (Maskov et al
water tank immcount that whnecessary to
uencies higherH), band fromtrasonic wavevibrating. Hoion phenomenLitovitis, 1959parameters w
estner, 1987; Hthe number o
ntical to the freis the propagaa characteris
avelength. Horessure, tempeeglected. For t
n for ultrasonic
us of elasticity s and ρ is the dZ): not all mate materials oe of the acousIf a medium hpressure; that
ontrary, the ime the mediumformula:
Mod
oncepts n made by imman, 1971), in talmost alway
s directly relatof the probe 20 mm. Usingl., 2000; Mars
mersion systemhen an ultrason
know for a br than 20 KH,
m 0.2 to 25 MHes can propagowever, thesena, so not all m9).
will be definedHarvey, 1963;f oscillations oequency of thation velocity stic of the mawever, this is
erature and oththis reason, thic testing. The a𝐶
(N/m2), µ is tdensity of the erials will behppose to the stic wave or shas a low impeis, the medium
mpedance is him offers great𝑍 𝜌.
dern Applied Sc
35
mersion testinthis case the sps water with thted to the quanozzle is crit
g this techniqush, 2002; Vad
m. Right: Meanic beam passbetter interpret
within this baHz and frequengate through ae waves are amedia are suita
d for the study; Mundry, 196of a particle p
he generator, wof the wave fo
aterial and, ins not strictly her parametersis speed can bacoustic veloc. µ. µ . µ
the Poisson comaterial (Kg/
have the samepassage of th
specific acousedance, its mam will offer litigh, the mass t resistance to. 𝐶 (Kg
cience
ng of the specipecimen and the necessary aality of the watical as it canue, panel or precantos, Migu
asured on the pses through a mtation of the rand we can spncies above 10any material mattenuated by able for transm
y to be carried68). per second. Wiwhich can be cor a given con
n general, is caccurate, sincs. However, ine taken approx
city for a longi
(m/s)
oefficient (dim/m3).
e way when thhe ultrasonic stic impedancass elements wttle resistance elements wil
o elastic defo
g/m2.s)
imen (Silk, 19he probe are im
additives to preater jet, and m
n cause disturrobe inspectionuel, & Gallego
part by immermaterial, certaresults. When peak of nearby00 MHz whichmedium, wheall materials
mitting ultraso
d out (Alonso
ithin the samechosen arbitrarndition, for exaconstant for a ce such speedn many solid mximately as a citudinal wave
mensionless) q
ey are crossedwave is wha
ce. It is a resiswill vibrate at to the elastic l vibrate slow
ormations. Exp
Vol. 15, N
982; Huang etimmersed (76 revent corrosiomore specificarbances. The n is much fasto, 1995).
rsion transmisain physical ph
n we speak of y ultrasound (h is the field o
ere there are as according toound (Ramirez
& Finn, 1987
e wave, it is tharily. ample, in a coma given materid depends, espmaterials, suchconstant of theis given by th
quotient betwe
d by an ultrasoat is known astance that ophigh speed, wdeformations
wly, even if thxperimentally,
No. 1; 2021
t al., 2000; mm water
on damage. ally to the separation ter and can
sion henomena ultrasonic
(frequency of acoustic atoms and o different z Lopez et
7; Pollock,
e same for
mpression ial, at any pecially in h as metals, e material, e formula:
(1)
een lateral
onic wave. as acoustic pposes the with only a
caused by he acoustic
it can be
(2)
mas.ccsen
which indcalled "acKg/m2.s).On the othmedia, a propagatethe reflecgraphical
It can be medium IWe call R
Both are in relationThe energtheory of
It can be don whichspecific a
and the so
where w iwe can pu
in such a
net.org
dicates that thcoustically har. Impedance inher hand, if a part of the enes in the seconcted one, It thelly exposed as
Fseen from fig
II and C is theR the reflectio
dimensionlessn to the incidegy balance expf propagation o
deduced that fh the wave affeacoustic energ
ound intensity
is the angular ut the followin
way that it ca
he acoustic imrd" (steel withn solid bodiesflat acoustic w
nergy of the wnd medium me transmitted os follows:
Figure 5. Perpgure 5 above, e energy reflecn coefficient a
s coefficients ent intensity. pressed in inteof acoustic wa
from the pointects since the
gy is given by:
y by the follow
frequency, A ng expression
an be put:
Mod
mpedance is a h Z = 45.106 Ks is generally hwave falls perpave is reflecte
maintaining its one and Z1 an
pendicular incithat A is the
cted on the boand T the tran𝑅𝑇that express th
ensities remaiaves it is obtai𝑅𝑇t of view of thvalues of R an
: 𝐸wing formula:𝐼is the amplitu
ns of the coeffi𝑅 𝑇𝑅′𝑇′
dern Applied Sc
36
a constant of tKg/m2.s) in conhigher than inpendicularly oed and returnsdirection and
nd Z2 the respe
idence of the incident ener
oundary surfacnsmission coef𝑅 ; 𝑇
the percentage
ins: 𝐼 𝐼 ined that: 𝑅 ;
he acoustic inteand T do not ch
𝜌𝑉
𝜌𝐶𝑉ude and P is theficients of refle;
;
cience
the material. Mntrast to "acou
n liquids and, ion a flat and sos in the same dd sense. If Ii isective acousti
sound wave orgy, B is the ece I, so that A fficient that ar
e of reflected a 𝐼 and there
;
ensities, it is inhange when e
𝜌𝑤 𝐴𝑍𝑉 𝑍𝑤
e sound pressuection and tran
= √𝑅 = 𝑇
Materials withustically soft" in these, higheoft surface thatdirection of th the intensity c impedances
on a flat surfacenergy transm= B + C.
re given by:
and transmitte
efore can be p
ndifferent the exchanged betw
𝑊/𝑤 𝐴 𝑊ure. Taking innsmission of s
Vol. 15, N
h a high impe(water with Z
er than in gaset separates two
he incident, anof the inciden
s of the materi
ce mitted from me
ed intensity re
put: R + T = 1
side of the limtween Z1 and Z
/𝑚
𝑊/𝑚
nto account thisound pressur
No. 1; 2021
edance are Z = 1,5.106 es. o different nother part nt wave, Ir ials, this is
edium I to
(3)
(4)
spectively
. From the
(5)
(6)
mit surface Z2. As the
(7)
(8)
is equation, re:
(9)
(10)
(11)
(12)
mas.ccsenet.org Modern Applied Science Vol. 15, No. 1; 2021
37
From the expression 11 it is deduced firstly that the reflected acoustic pressure will be of the same amplitude, whatever the side of the limit surface on which the wave is incident, that is to say, independently of the sequence of both materials; although in the case of being Z2>Z1, R' will be positive, which indicates that the incident wave and the reflected wave are in phase and, in the opposite case (Z2<Z1), R' will be negative, which indicates an inversion of the phase of the reflected wave in relation to the incident wave. From the expression 12 it is deduced that although the acoustic pressure transmitted in phase with the incident, it will not be independent of the sequence of the two materials, so that if Z2>Z1, then T'>1, which indicates that its amplitude will be greater than that of the incident wave and, in the opposite case (Z2<Z1, T'<1) less. Finally, the balance of sound pressure, in contrast to energy or sound intensity, can be put as
Pi + Pr = Pt, either 1 +R’ = T’ which implies that for balance to be maintained, the sum of the pressures must be the same on both sides of the interface. 2.2 Methodology Applied to the Real Case The determination of possible defects in composite materials widely used in the industrial sector, is the problem to be addressed once established the theoretical foundations of the physical interaction of an ultrasonic wave with matter. It is important that the use of these materials at a technological and industrial level guarantees that they do not have defects that reduce their mechanical properties considerably, especially in critical structures. The main defects to be evaluated are:
• The punctual or generalized porosity that will be basically air inclusions within the polymeric matrix that could have been produced by a low pressure application in the resin curing process in its manufacturing process or by a movement between layers after the resin has started its molecular crosslinking process (Heru et al., 1997).
• In epoxy matrix carbon fiber laminates, low energy impacts cause damage that can result in dents, matrix cracking, fiber to matrix delamination and fiber breakage. Of all these, delamination is probably the most harmful due to the difficulty in detecting it and the reduction it causes in the properties (Baker; Jones & Callinan, 1985; Wróbel, Wierzbicki & Pawlak, 2005). The possible delaminations of a carbon fiber layer will be evaluated, these will be identified by the presence of air due to the detachment of successive layers of fiber due to lack of adhesion between them (Cantwell, Curtis, & Morton, 1986; Miyano et al., 1994).
In Table 1, some physical and mechanical properties of some materials that will be used in the ultrasonic inspection process to be developed on the chosen composite material have been collected. Table 1. Physical and mechanical data on some materials
Material Densidad Ρ (Kg/m3)
Módulo elástico E (Gpa)
Coeficiente de Poisson (adimensional)
Resina epoxy Modificada 8552
1100 3,4 0,4
Fibra de carbono (AS4 alta resistencia)
1790 330 0,1
Agua 1000 --- --- Aire 1,22 --- ---
In the technical inspection performed by ultrasound we will find, first the water layer, since it is an inspection by immersion in water, then the polymer matrix formed by an epoxy resin type, the carbon fiber used as reinforcement, and finally, the presence of air in the form of porosity or delamination. The speed of sound propagation in the different media (CL) and the acoustic impedance (Z) will be determined, since the amount of reflected and transmitted sound will be obtained from these parameters. It will be taken into account that the speed of sound in air is 340 m/s and in water 1435 m/s, and therefore, it is not necessary to calculate them.
mas.ccsen
2.2.1 InspWe are gomaterial. have beenthe panel the combWe will spropagatea frequenThe studyand then,The follothe ultras
Figure 6.
Phase 1: WUsing theTable 1 fofollowingTable 2. A
Using forresults suTable 3. P
In this caindicates incident w
net.org
pection for Pooing to try to We have alre
n able to deterdue to lack of
bination of watstart the ultrases). It will be t
ncy of 1 MHz y will be carrie in a second pwing figure sh
sonic inspectio
. Distribution
Water + epoxe formulas of or the two matg results are reAcoustic velo
M
AR
rmulas 11 andummarized in Percentage of
ase, Z2>Z1 is that T'>1, w
wave. The tran
orosities determine if i
eady seen thatrmine them byf pressure durter, epoxy resonic inspectiotaken into accothat will proded out in two pphase, the epoxhows in schemon to locate th
of layers in th
xy resin the speed of
terials that areeached: city and impe
Material
Agua esina epoxy 8
d 12 of the refTable 3. In th
f reflected andMaterial
Agua Resina epox
positive, indhich implies nsmitted wave
Mod
t is possible tot one of the pay means of imming the forminin and air.
on study takingount that the in
duce an intensiphases, that is,xy resin will b
matic form thehe porosity in t
he study of poflat s
sound propage analyzed in th
edance of wateVeCL
148552 25flected and trais case the wa
d transmitted w
xy 8552 icating that ththat the ample has an acous
dern Applied Sc
38
o detect if theranels (P1) hasmersion ultrasng process, it w
g into accountnspection willity of 200 dB., first the matebe studied wite components othe material.
orosity with pesurface of the
gation (1) and his phase, mat
er and epoxy relocidad acúst
L (m/s) 435 573,59 ansmitted sounater will be mawave from wa
ReflectanciaR’ (%) 32,55
he incident anlitude of the stic pressure o
cience
re are air poros been preparesounds as showwill appear in
t the water firsl be performed. erials such as wth the air. of the materia
erpendicular inplate
the acoustic iterial 1 the wa
resin tica Imped
Z (Kg1,442,83
nd pressures raterial 1 and th
ater and epoxya Transm
T’ (%132,55
nd reflected wtransmitted w
of 132.55%. T
osities in the med expressly fwn in figure 2the epoxy res
st (where the ud using a norm
water and epox
als to be taken
ncidence of th
impedance (2ater and materi
dancia acústica/m2.s)*106
respectively, whe epoxy resin
y resin mitancia ) 5
waves are in wave will be gThis we will re
Vol. 15, N
manufactured for this purpo2b. If there is psin, so we mus
ultrasonic beammal incidence p
oxy resin will b
into account t
he acoustic wa
2) and the paraial 2 the epoxy
a
we obtain the n will be mate
phase. Beinggreater than tepresent in fig
No. 1; 2021
composite ose and we porosity in st evaluate
m initially probe with
be studied,
to perform
ave on the
ameters of y resin, the
following erial 2.
g Z2>Z1, it that of the gure 7.
mas.ccsen
Figure 7 shown is the produwave (13Phase 2: EFor this slack of prof epoxy Table 4. A
Using forresults suTable 5. P
In this caindicates that T'<1 graphical
net.org
Figurshows the valthe transmitte
uct of multiply2.55%) whichEpoxy resin +
study procedurressure duringresin with air
Acoustic veloM
RA
rmulas 11 andummarized in Percentage of
Ma
ReAir
ase of searchina phase inverwhich implie
lly the results
re 7. Acousticlues of the inced wave (greeying the incidh gives intensi+ air re, it will be o
g the forming pr, the first willcity and impe
Material
esina epoxy 8Aire d 12 of the refltable 5.
f reflected andaterial
sina epoxy 85re ng for porosityrsion of the rees that the tranobtained.
Mod
c pressures in tcident (blue) aen) in the epoxdent power (20ities of 65.1 d
operated in a sprocess, it will be material 1
edance for epoVeCL
8552 2534
ected and tran
d transmitted wReR’
552 -99
y in the sampleflected wave nsmitted wave
dern Applied Sc
39
the case of refand reflected (xy resin matri00 dB) by the
dB and 265.1 d
similar way asl appear in the
1 and air will boxy resin and aelocidad acúst
L (m/s) 573,591435 40 nsmitted acous
wave for epoxeflectancia (%) 9,97%
le, it has beenwith respect t
e is smaller th
cience
flection in wa(orange) wavex. The reflect
e percentage odB respectivel
s in phase 1. Ie epoxy resin, be material 2.air tica Imped
Z (Kg2,830,0004
stic pressures
y resin and airTransT’ (%0,028
n obtained thatto the inciden
han the inciden
ater and epoxye pressures in med and transm
of reflected (32ly.
f there is poroso we must ev
dancia acústica/m2.s)*106
41 respectively, w
r mitancia
%) %
t Z2<Z1, so thnt wave. As Z2nt wave. Figu
Vol. 15, N
y resin medium I (wa
mitted intensiti2.55%) and tr
osity in the pavaluate the co
a
we obtain the
hat R' is negati2<Z1, it is also
ure 8 below w
No. 1; 2021
ater). Also ies will be ransmitted
anel due to mbination
following
ive, which o obtained ill express
mas.ccsen
Figure 8 sI (epoxy rintensitieand transthe incideconsideraintensity total (ther2.2.2 InspIf there itherefore,matrix, thcarbon fib
Figure 9.
For the stthe first pand for thquantity delaminaPhase 1: WThe data transmittadB. This
net.org
shows the valresin). It also s will be the pmitted wave (ent wave is eqation, the reflof the transmire is almost nopection for Deis a delaminat, it will be takhe carbon fibeber. The schem
Distribution o
tudy of delamiphase the watehe third and lasof wave that
ation. Water + epoxobtained for tance of 132.55value will be
Figure 8. Acoues of the preshows the tran
product of mu(0.028%). To qual to the inteected intensititted wave is po attenuation)elaminations tion in the mken into acco
er and finally ime can be see
of layers in the
ination identifer and epoxy mst one, the cart crosses the
xy resin the inspection5%, which tranthe one that in
Mod
oustic pressureessures of the insmitted waveltiplying the indetermine the
ensity of the wty will be 265practically zer, so that the p
aterial, it willount that the uit will meet then in the follow
e study of delathe fla
fication, it wilmatrix will bebon fibre and carbon fiber
n for porosity nslates into a rn the study of
dern Applied Sc
40
es in the case incident wavee (green) in aincident powere intensities, iwave transmitt5.02 dB and ro, however, t
porosity can be
l occur betweultrasonic beahe delaminatiowing figure 9.
aminations wiat surface of thll be studied ine selected, forthe air (possib
r is the great
will be valid reflected inten
f the second ph
cience
of epoxy resine (blue) and rer (possible por (200 dB) by t should be tated in the prevthe transmitte
the intensity oe easily identi
een layers of am will pass ton (if any) bef.
ith perpendicuhe plate n three phasesthe second th
ble delaminatiter possible t
for this phasensity of 65.1 dhase enters as
n and porosityeflected wave rosity). The rethe percentag
aken into accovious phase, ieed intensity wf the reflectedfied.
carbon fiber hrough the w
fore passing th
ular incidence
s each with a she epoxy matrion). It is interthing to be a
e, with a reflecB and a transmthe incident w
Vol. 15, N
y (orange) in theflected and trge of reflectedount that the ine 265.1 dB. Mwill be 0.0742d wave is prac
used as reinfwater layer, thhrough the nex
of the acousti
set of two matrix and the carresting above aable to detect
ctance of 32.5mitted intensitwave value.
No. 1; 2021
he medium ransmitted
d (99.97%) ntensity of
Making this 2 dB. The ctically the
forcement, e polymer xt layer of
ic wave on
terials. For rbon fibre, all that the t the later
55% and a ty of 265.1
mas.ccsen
Phase 2: ETaking inand acousTable 6. A
Using equTable 7. Table 7. P
In this caBeing Z2>that of theof its impfigure 10
Figure 10I (epoxy intensitieand transbeneficiaPhase 3: CIt remainspossible dtransmitteTable 8. A
net.org
Epoxy resin +nto account eqstic impedancAcoustic velo
Ma
ReFib
uations 11 and
Percentage of M
RFi
se you have to>Z1, it indicate incident wavpedance Z, th.
Figure 10. A0 shows the varesin). Also ss will be the p
smitted wave al if what is soCarbon fiber +s to be studieddelamination ed previously,Acoustic velo
M
FiA
+ carbon fiber quations 1 andce of the two mcity and impeaterial
esina epoxy 85bra de carbonod 12, the reflec
f reflected andMaterial
esina epoxy 8ibra de carbono Z2>Z1 so R' tes that T'>1, wve. Because ce transmitted
Acoustic pressualues of the preshown is the
product of mul(179.34%) whught is that th+ air (delamind how the acou(presence of , that is, the oncity and impe
Material
ibra de carbonAire
Mod
d 2, and the vamaterials listededance for epo
VelCL
552 257o AS4 137cted and transm
d transmitted wReR’
8552 79no AS4 is positive, whwhich impliesarbon fiber hawave will inc
ures in the delessures of the transmitted wltiplying the inhich gives int
he acoustic wanation): ustic wave woair). It shouldne with an int
edance of carbVeCL
no AS4 1334
dern Applied Sc
41
alues of the and in Table 6 hoxy resin and clocidad acústi(m/s)
73,591435 731,25 mitted acousti
wave for epoxeflectancia ’ (%) 9,34%
which indicatess that the ampas a greater cacrease its pow
lamination stuincident wave
wave (green) incident powertensities of 21ave reaches th
ould react whend be noted agatensity of 475.bon fiber and pelocidad acúst
L (m/s) 3731,25 40
cience
nalyzed materhave been detecarbon fiberica Impe
Z (Kg2,8324,57
ic pressures ha
y resin and caTransmT’ (%179,34
s that the incidplitude of the tapacity to tranwer to 179.34%
udy case for epe (blue) and rein the carbon r (265.1 dB) by10.33 dB and e possible del
n passing throain, that the in.43 dB. possible delamtica Imped
Z (Kg24,570,0004
rials referenceermined.
dancia acústicg/m2.s)*106
7 ave been deter
arbon fiber mitancia ) 4%
dent and reflectransmitted wa
nsmit sound, a%. We are go
poxy resin andeflected wave fiber. The re
y the percenta475.43 dB reamination.
ough the carboncident wave
mination (air) dancia acústica/m2.s)*106
41
Vol. 15, N
ed in Table 1,
ca
rmined and are
cted waves arewave will be gras indicated byoing to repres
d carbon fiber(orange) in th
eflected and trage of reflecteespectively. Th
on fiber and reis the one cal
a
No. 1; 2021
the speed
e shown in
e in phase. reater than y the value ent this in
r he medium ransmitted d (79.34%) his data is
aching the lculated as
mas.ccsen
Table 9. P
In this cawhich indobtained express g
Figure 11medium Iand transmreflected respectivehowever,identify adelaminaattenuatioit should 3. ResultThis studidentifiedUltrasounentire voldetectionis accurataccess byprocess omakes poobservingto undertadisadvantcomplicaof a coupsystem ansamples.
net.org
Percentage of M
FiA
ase of searchindicates a phasthat T'<1 wh
graphically the
Figure 11. Ac1 shows the vaI carbon fibermitted intensi(99.99%) an
ely. The refle the transmitte
a signal of 0.0ation in this tyon of the signabe considered
ts dy of defect idd in this type onds, as a NDTlume of the sa
n of very smalltely determiney a surface to of signal generossible an adeqg the test, theyake a great amtages, such a
ated to inspect,pling fluid, hend the determ
f reflected andMaterial
ibra de carbonAire
ng for delaminse inversion ohich implies the results obtain
coustic pressualues of the pr). The transmities will be thnd transmittedcted intensityed one is very0156 dB that wype of sampleal that had beed to work with
dentification iof material usiT technique, hample but withl defects (depeed, as well as th
perform the ration and recquate documey have a high vmount of induas requiring , the passage o
eterogeneities mination of ce
Mod
d transmitted wReR’
no AS4 -9
nations in the of the reflectehat the transmned.
res in the delaressures of th
mitted wave (ghe product of md wave (0.00
is practicallyy small. Therefwould be a qu
es with the sigen emitted is ph higher frequ
in composite ing the techniqhas a high penh the ability toending on the he estimation test, the resul
ception is contentation of it, tversatility sinstrial problemhighly qualif
of acoustic enevery close to
ertain characte
dern Applied Sc
42
wave for carboeflectancia ’ (%) 9,99%
e sample, it haed wave with mitted wave i
amination studhe incident wagreen) is also multiplying th033%) which y the same as tfore, 0.0033%uite low signagnal used of 1
practically totauencies and sou
materials hasque of ultrasonetration powo test greater tquality of theof size, orient
lt of the inspetrolled electrothere are no ri
nce the ultrasoums (Miyano et fied personneergy from the the surface meristics of the
cience
on fiber and pTransmT’ (%0,0033
as been obtainrespect to the
is smaller tha
dy case for carave (blue coloshown in the
he incident powgives intens
the one that h% of the dB wilal. Probably, i1 MHz frequeal. Therefore, iund intensitie
s shown how ound immersiower because inthicknesses, hamaterial anal
tation, shape aection is instanonically, the tesks for the opund test has aal., 1986; Wa
el, small, irr probe to the s
may not be dedefects requi
ossible delammitancia ) 3%
ned that Z2<Z1e incident wavan the inciden
rbon fiber andr) and reflectepossible delamwer (475.43 dities of 475.3
has come fromll be transmittit would not bency and 200 in order to idens.
porosities andon. n the test provas a high sensyzed), the pos
and nature of hntaneous (reaechnique of imerator or for thgreat amount
an et al., 2016egular, roughsample and vicetected and thires the use o
Vol. 15, N
mination
1, so that R' isve. As Z2<Z1
nt wave. Figu
d delaminationed wave (oran
amination. ThedB) by the per38 dB and 0
m the carbon fted, so the detebe possible to
dB intensity,entify this type
d delaminatio
vides informatsitivity which sition of internheterogeneity,al time) since mage capture the people whot of resources 6). They also hh or thin samceversa requir
he calibration of standard or
No. 1; 2021
s negative, , it is also re 11 will
n nge) in the e reflected centage of
0.0156 dB fiber layer, ector must identify a
, since the e of defect,
ons can be
tion of the allows the nal defects only need the whole of the test o could be that allow
have some mples are res the use of the test
r reference
mas.ccsenet.org Modern Applied Science Vol. 15, No. 1; 2021
43
Calculations of the percentages of acoustic intensities of reflected and transmitted waves allow more or less easily to determine if it is possible to detect defects (porosity and delaminations) in a material (composite). It will be taken into account that for the inspection of delaminations, an almost complete attenuation of the transmitted wave is produced, so in practice, for the search of this type of defects, it should be taken into account to work with higher frequencies, as well as acoustic intensities. 4. Discussion Unidirectional components are not commonly used in aerospace structural components due to their high anisotropy of mechanical properties. Normally multidirectional laminates are used which are optimal for different load conditions (Miyano et al,,1986; Marsh, 2002; DobrzaÉski, 2002). Even so, it is necessary to study unidirectional laminates since this allows us to know how the material behaves in the direction of the fibers, since the sheet presents maximum properties in this direction and minimum properties in the transversal direction. The tested laminate presents the highest resistance and elastic module and the lowest possible thermal expansion coefficient in one direction. The study of the use of the physical phenomena of interaction of the ultrasonic wave in the composite material is an excellent tool to identify defects by ultrasound in this type of materials. This will help the beginners who are initiated in the application of this type of methodologies (especially the ultrasounds) in the laboratories to be able to adjust in a theoretical way the measurement devices, one of the most pronounced difficulties in this type of measurements. This will also provide an approximate idea of the frequency and intensity of work for certain types of materials and defects, reducing preparation times and costs of testing. Acknowledgements The authors wish to thank CEU San Pablo University Foundation for the funds dedicated to the Project Ref. USP CEU-CP20V12 provided by CEU San Pablo University. References Alonso, M., & Finn, E. (1987). Física. Vol II (Campos y Ondas). Ed. Addison Wesley,
Iberoamericana,Wilmington. ASM International Handbook Committee. (1989). Engineered Materials Handbook, 1, Composites. Baker, A. A., Jones, R., & Callinan, R. J. (1985). Damage tolerance od graphite/epoxy composites. Composite
Structures, 4(1), 15-44. https://doi.org/10.1016/0263-8223(85)90018-2 Barbero, E. J. (1999). Introduce to Composite Materials Design. Taylord & Francis, Inc. Bishop, S. M. (1985). The mechanical performance and impact behavior of carbon fibre reinforced PEEK.
Composite Structures, 3, 295-318. https://doi.org/10.1016/0263-8223(85)90059-5 Cantwell, W. J., Curtis, P., & Morton, J. (1986). An assesment of the impact performance of CERP reinforced with
high-strain carbon fibres. Composite Science Technology, 25(2), 133-148. https://doi.org/10.1016/0266-3538(86)90039-4
DobrzaĔski, L. A. (2002). Fundamentals of Materials Science and Physical Metallurgy. WNT, Warszawa (in Polish).
Dunegan, H. L., & Tetelman. (1971). Acoustic Emission. Research and Development, 22(5), 20-24. Gray, S., Ganchev, S., Qaddoumi, N., Beauregard, G., & Radford, D. (1995). Porosity level estimation in
polymerer composites using microwaves. Applied Microwave Nondestructive Testing laboratory, Electrical Engineering Department, Colorado State University, Ft. Collins. Material Evaluation, 404-408.
Harvey, A. (1963). Microwave Engineering. Academic Press. Heru, S. B., Komotori, J., Shimizu, M., & Miyano, Y. (1997). Effects of the fiber content on the longitudinal
tensile fracture behavior of uni-directional carbon/epoxy composites. Journal of Materials Processing Technology, 67, 89-93. https://doi.org/10.1016/S0924-0136(96)02824-5
Hervfeld, K. F., & Litovitis, T. A. (1959). Absorption and Dispersion of Ultrasonic Waves, 535. Huang, Y. D., Liu, L., Zhang, Z. Q., & Wan, Y. (1998). On-line monitoring of resin content for film
impregnation process. Composites Science and Technology, 58, 1531-1534. https://doi.org/10.1016/S0266-3538(97)00185-1
mas.ccsenet.org Modern Applied Science Vol. 15, No. 1; 2021
44
Huang, Y. D., Liu, L., Qui, J. H., & Shao, L. (2002). Influence of ultrasonic tretment on the characteristics of epoxy resin and the interfacial property of its carbon fiber composites. Composites Science and Technology, 62(16), 2153-2159. https://doi.org/10.1016/S0266-3538(02)00148-3
ImieliĔska, K., Castaings, M., Wojtyra, R., Haras, J., Le Clezio, E., & Hosten, B. (2004). Air-coupled ultrasonic C-scan technique in impact response testing of carbon fibre and hybrid: glass, carbon and Kevlar/epoxy composites. Journal of Materials Processing Technology, 157-158, 513-522. https://doi.org/10.1016/j.jmatprotec.2004.07.143
INASMET. (1998). Materiales compuestos. Tecnologías de producción. Centro tecnológico de materiales Inasmet, San Sebastián, España.
Kapranos, P., & Priestner, R. (1987). NDE of difusión bonds. Metals and Materials, 194-198. KINO, G. S. (1979). Acoustic imaging for nondestructive evaluation. IEEE, 67(4), 510-525.
https://doi.org/10.1109/PROC.1979.11280 Marsh, G. (2002). Finding flaws in composites. Reinforced Plastics, 46(12), 22-28.
https://doi.org/10.1016/S0034-3617(02)80227-2 Maslov, K., Kim, Y. R., Kinra, K. V., & Pagano, J. N. (2000). A new technique for the ultrasonic detection of
internal transverse cracks in carbon-fibre/bismaleimide composite laminates. Composite Science and Technology, 60, 2185-2190. https://doi.org/10.1016/S0266-3538(00)00013-0
Miyano, Y., Kanemitsu, M., Kunio, T., & Kuhn, H. A. (1986). Role of matrix on fracture strengths of unidirectional CFRP. Journal of Composite Materials, 20, 520-538. https://doi.org/10.1177/002199838602000602
Miyano, Y., McMurray, M. K., Kitade, N., Nakada, M., & Mohri, M. (1994). Role of matrix resino n the flexure static behavior of unidirectional pitch-based carbon fiber laminates. Advanced Composite Materials, 4(2), 87-99. https://doi.org/10.1163/156855194X00222
Mouritz, A. P., Townsend, C., & Shah Khan, M. Z. (2000). Nondestructive detection of fatigue damage in thick composites by pulse-echo ultrasonics. Composites Science and Technology, 60, 23-32. https://doi.org/10.1016/S0266-3538(99)00094-9
Mundry, E. (1968). Ultrasonidos. Trad. Ed. 1961. INTI. Argentina, 124. Nesvijski, G. (2000). Some aspects of ultrasonic testing of composites. Composite Structures, 48, 151-155.
https://doi.org/10.1016/S0263-8223(99)00088-4 Ochelski, S. (2004). Experimental methods in construction composites mechanics. WNT, Warszawa (in Polish). Padmanabhan, K., & Kishore, E. (1995). Failure behaviour of carbon fibre/epoxy composites in pìn-ended
buckling and vending test. Composites, 26(3), 201-206. https://doi.org/10.1016/0010-4361(95)91383-G Pollock, A. A. (1987). Acoustic Emission Inspection. Metals Handbook, 17. Non Destructive Evaluation and
Quality Contro, 278-294. Potel, C., Chotard, T., Belleval, J. F., & Benzeggagh, M. (1998). Characterization of composite material by
ultrasonic methods. Composites Part B, 159-169. https://doi.org/10.1016/S1359-8368(97)00006-1 Rámirez López, Fc., Del Ojo, G., Fernández Soler, M. A., Valdecantos, C., Alonso, A., & De los Ríos, J. M. (1996).
Métodos de Ensayos No Destructivos. Instituto de Técnica Aeroespacial (INTA). Ramírez, F., & Col. A. (1982). Introducción a los métodos de ensayos no destructivos de control de calidad de los
materiales, 3ª edición, INTA, Madrid, Spain. Richardson, E. G. (1952). Ultrasonic Physics. Elsevier Publishing Companu, Amsterdam, London, New York.
https://doi.org/10.1063/1.3067396 Rojek, M., Stabik, J., & Wróbel, G. (2005). Ultrasonic methods in diagnostics of epoxy-glass composites.
Journal of Materials Processing Technology, 162-163. https://doi.org/10.1016/j.jmatprotec.2005.02.069 Sanglier, G., Del Ojo, G., De Miguel, J., & Peñaranda, J. A. (2003). Estudio mediante Ensayos No Destructivos de
la cubierta (“Radomo”) de un sistema experimental de radar de apertura sintética. 10º Congreso Nacional de E.N.D. Asociación Española de Ensayos No Destructivos. Cartagena, España.
mas.ccsenet.org Modern Applied Science Vol. 15, No. 1; 2021
45
Scarponi, C., & Briotti, G. (2000). Ultrasonic technique for the evaluation of delamination on CFRP, GFRP, KFRP composite materials. Composites, Part B 31, 237-243. https://doi.org/10.1016/S1359-8368(99)00076-1
Silk, M. G. (1982). Defect detection and sizing in metals using ultrasound. International Metal Rev., 1, 28-50. https://doi.org/10.1179/imr.1982.27.1.28 Vaccaro, C., & Akers, D. (1996). Damage assesment in a SMC composite by means of ultrasonic techniques.
Review of Progress in Quantitative Nondestructive Evaluation, 13. Plenum Press, New York. Valdecantos, C., Miguel, J., & Gallego, E. (1995). Ensayo por ultrasonidos de materiales compuestos. Técnicas de
impulso eco. 5º Congreso español de técnicas END. Sevilla, Spain. Wan, H., Ning, F., Hu, Y., Fernando, PKSC, & Pei, Z. J. (2016). Surface grinding of carbon fiber-reinforced
plastic composites using rotatory ultrasonic machining: Effects of tool variables. Advanced in Mechanical Engineering, 8(9), 1-14. https://doi.org/10.1177/1687814016670284
Wróbel, G., & Wierzbicki, A´. (2005). Ultrasounds in diagnosis of strength changes in laminates put in agening conditions. 3rd Scientific Conference on Materials, Mechanical and Manufacturing Engineering, 575-580.
Wróbel, G., Wierzbicki, A’., & Pawlak, S. (2005). Ultrasonic quality evaluation method for polyester glass laminated materials. 11th International Scientific Conference on Contemporary Achievements in Mechanics, Manufacturing and Materials Science. Gliwice - Zakopane, 1040-1044.
Copyrights Copyright for this article is retained by the author(s), with first publication rights granted to the journal. This is an open-access article distributed under the terms and conditions of the Creative Commons Attribution license (http://creativecommons.org/licenses/by/4.0/).