Composites: Part B 63 (2014) 61–66

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Composites: Part B

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Influence of seawater absorption on the vibration dampingcharacteristics and fracture behaviors of basalt/CNT/epoxymultiscale composites

http://dx.doi.org/10.1016/j.compositesb.2014.03.0101359-8368/� 2014 Elsevier Ltd. All rights reserved.

⇑ Corresponding authors. Tel.: +82 312012565; fax: +82 312026693.E-mail addresses: rheeky@khu.ac.kr (K.Y. Rhee), ijung@khu.ac.kr (I. Jung).

Man Tae Kim a, Kyong Yop Rhee b,⇑, Inhwa Jung b,⇑, Soo Jin Park c, David Hui d

a Airworthiness Certification Team, Defense Agency for Technology and Quality, Seoul 130-650, Republic of Koreab Department of Mechanical Engineering, Kyung Hee University, Yongin 446-701, Republic of Koreac Department of Chemistry, Inha University, Incheon 402-751, Republic of Koread Department of Mechanical Engineering, University of New Orleans, LA 70148, USA

a r t i c l e i n f o a b s t r a c t

Article history:Received 9 January 2014Received in revised form 18 February 2014Accepted 21 March 2014Available online 1 April 2014

Keywords:A. Polymer–matrix compositesB. Mechanical properties

In the present study, the effect of seawater absorption on the damping and fracture behaviors of carbonnanotube (CNT)-modified epoxy/basalt fiber (basalt/CNT/epoxy) multiscale composites was investi-gated. Forced vibration of a cantilever beam and fracture tests were performed using dry andseawater-saturated basalt/CNT/epoxy multiscale composites. The results showed that the vibrationdamping coefficient is increased approximately 50% by seawater absorption; the fracture behavior ofbasalt/CNT/epoxy multiscale composites was also significantly affected. Compliance of the seawater-saturated samples was increased and fracture load was decreased compared to the dry samples. Theaverage fracture toughness of seawater-saturated samples was approximately 20% lower than that ofdry samples. SEM examination of the fracture surfaces revealed that the decreased fracture toughnessof the seawater-saturated samples was due to the weakening of interfacial bonding from swelling ofthe epoxy matrix. This observation is crucial when the composites are used as marine structures suchas hull of the ship, and propeller.

� 2014 Elsevier Ltd. All rights reserved.

1. Introduction

Recent reports by many different researchers have indicatedthat multiscale composites with both nano- and micro-sizedreinforcing materials within the polymer matrix possess bettermechanical and thermal properties than do conventionalfiber-reinforced composites [1–5]. For instance, Sanchez et al. [6]reported that carbon nanotube (CNT)-reinforced carbon/CNT/epoxy multiscale composites showed improved flexural strengthand interlaminar shear strength compared to carbon/epoxy com-posites. They also reported that this effect was more evident inmultiscale composites filled with functionalized CNTs. Kim et al.[7] investigated the effect of CNT additions on the flexural behav-iors of carbon/epoxy composites. Their results demonstrated thatthe flexural modulus and strength of carbon/CNT/epoxy compos-ites were 10% and 15% greater, respectively than those of carbon/epoxy composites. Ashrafi et al. [8] revealed that the addition ofsingle-walled carbon nanotubes (SWCNTs) into carbon/epoxy com-

posites significantly improved the impact resistance and fracturetoughness of carbon/epoxy composites. SWCNTs at similar loadinglevels have also been shown to be more effective than multi-wallcarbon nanotubes (MWCNTs) in enhancing the mechanical perfor-mance of carbon/epoxy composites. Mahesh et al. [9] reported theinfluence of nanoparticle montmorillonite (MMT) additions on themechanical properties of vinylester/glass composites. Their resultsindicated that the tensile strength, interlaminar shear strength,flexural strength, impact strength and fatigue life of the vinylest-er/glass composites all increased with the addition of 4 wt%montmorillonite.

Basalt fiber has a higher tensile strength than glass fiber and abetter fracture strain than carbon fiber. Moreover, basalt fiberhas excellent chemical stability, and is non-toxic and non-combus-tible; it can also be easily and cheaply fabricated by a simple pro-duction process. For this reason, many studies have beenconducted to investigate the application of basalt fiber as a rein-forcing material in various composites [10–14]. However, only afew studies have been conducted on the mechanical behavior ofbasalt fiber-reinforced multiscale composites. It was reported byLee et al. [15] that the tensile strength and Young’s modulus of

laser displacement sensor

impact hammer

data acquisition

system

signal conditioning

amplifier

signal conditioning

amplifier

computer

2mm

5 mm

25 mm

100 mm

10 mm

impact point displacement measuring point

force transducer

(a)

(b)

Fig. 1. Experimental setup for forced vibration of a cantilever beam.

62 M.T. Kim et al. / Composites: Part B 63 (2014) 61–66

basalt/CNT/epoxy multiscale composites were 19 and 15% greater,respectively, than those of basalt/epoxy composites. Recently, Kimet al. [16] investigated the effect of CNT modification with silane onthe fracture behavior of basalt/CNT/epoxy multiscale composites.They reported that the mode I fracture toughness of silane-treatedbasalt/CNT/epoxy multiscale composites was �40% greater thanthat of acid-treated basalt/CNT/epoxy multiscale composites.

The vibration characteristics of composites are importantbecause these materials are often applied to systems exposed toexternal impact and periodic loading. Typically, elastic propertiesand vibration characteristics of composites can be controlled byinclusion of nanomaterials. [17–23] Due to visco-elastic behaviorof nanomaterials at the interface, nanotube-reinforced compositeexhibits damped oscillation behavior. Such nonlinear vibrationcharacteristics can be modeled by the Kelvin-Voigt visco-elasticplate theory [24–27].

One of the most important issues for polymeric composites isthat their mechanical properties degrade when exposed to envi-ronmental conditions such as humidity and temperature. Themoisture absorption of polymers causes plasticization andswelling, weakening of the interfacial bond strength between thepolymer matrix and reinforcing materials. However, little researchhas been performed to investigate the fracture behaviors of seawa-ter-absorbed basalt/CNT/epoxy multiscale composites. In particu-lar, no research has been reported on the effect of seawaterabsorption on the damping behavior of basalt/CNT/epoxymultiscale composites.

For the present study, we have investigated the effect ofseawater absorption on the vibration damping characteristics andfracture properties of basalt/CNT/epoxy multiscale composites.Damping and fracture tests were performed using dry and fullyseawater-saturated basalt/CNT/epoxy multiscale composites.Following the fracture tests, scanning electron microscopy (SEM)was used to examine the fracture surfaces and determine failuremechanisms due to seawater absorption.

2. Experimental detail

The reinforcing materials used were woven-type basalt fiberswith an area density of 260 g/m2 and 12 lm diameter(EcoB4-F260, Secotech, Korea) and multi-walled carbon nanotubes(MWCNTs, CM-95, Hanhwa Nanotech, Korea) prepared by a chemi-cal vapor deposition method. The epoxy used was diglycidyl ether ofbisphenol A (YD-115, Kukdo Chemical, Korea), and the curing agentwas polyamidoamine (G-A0533, Kukdo Chemical, Korea). Thereagents used for the silane treatment were nitric acid (60–62%, Jun-sei Chemical, Japan), sulfuric acid (95%, Junsei Chemical), acetone(99.5%, Dae Jung Chemical, Korea), and ethanol (99.5%, Aldrich,USA), 3-aminopropyltriethoxysilane (99%, Aldrich, USA).

It was reported in the previous study that the silane-treatedCNT/basalt/epoxy multiscale composites possessed better fractureproperties than the acid-treated CNT/basalt/epoxy multiscale com-posites. Therefore, CNT was treated using 3-aminopropyltriethoxy-silane and the silane treatment of CNTs was performed followingthe procedures described previously [16].

Basalt/CNT/epoxy multiscale composites were fabricated as fol-lows. Epoxy resin was mixed with hardener (2:1, v/v) and 1 wt%silane-treated CNTs. Eight plies of basalt fabric were then impreg-nated with the matrix, and the composites were cured in an auto-clave (ISA-CA30, Ilshin Co., Korea) at 3 kgf/cm2 and 120 �C for 2 h.For double cantilever beam (DCB) fracture specimens (width25 mm and length 200 mm), an initial delamination was madeby inserting a 50 mm Kapton film (thickness 13 lm) between thefourth and fifth plies. The damping and fracture specimens werekept immersed in sterile-filtered seawater (Sigma–Aldrich,

S-9148, USA) for up to 4 months. Mode I fracture tests were per-formed using DCB specimens at a loading rate of 0.5 mm/minaccording to ASTM D 5528-01 [28]. After the initial delaminationprogressed to a certain extent, the applied displacement wasreduced and then increased again to induce further delamination.This process was repeated more than 10 times until the delamina-tion increased to greater than 30 mm. At least three fracture testswere performed to ensure the reliability of the test results.

The damping properties of Basalt/CNT/epoxy multiscale com-posites were measured by the setup shown in Fig. 1. One end ofa damping specimen was clamped into a custom-made setupshown in Fig. 1a. The damping specimens were excited by animpact hammer (086C01, PCB piezotronics) at a position 10 mmfrom the clamp and the resulting vibrations were measured at aposition 5 mm from its free-end by a laser displacement sensor(LK-G30, Keyence). A multiple channel (Ch1, Ch2) data acquisitionsystem (SCADAS Mobile, LMS) was used for the experiment; thefirst channel (Ch1) was used to acquire the impact hammer forcesignal and the second (Ch2) was used to acquire sensor displace-ment data. The impact hammer force signal was used as the trig-gering signals. Time domain signals were acquired from bothchannels simultaneously; they were then transformed to thefrequency domain by fast Fourier transform (FFT) and further cal-culated to a FRF (frequency response function), which is the ratiobetween Ch1 and Ch2 in the frequency domain (Ch2/Ch1). In eachexperiment, the excitation force from the impact hammer wascontrolled to 15N ± 1.5N.

3. Results and discussion

Polymer matrix composites are superior to metals in terms ofcorrosion resistance to seawater; however, they suffer from degra-dation of mechanical properties after absorption of seawater. Theseawater content C of basalt/CNT/epoxy multiscale composites

Fig. 2. Seawater absorption curve at room temperature for CNT/epoxy/basaltmultiscale composites.

M.T. Kim et al. / Composites: Part B 63 (2014) 61–66 63

was calculated as a function of seawater immersion time from theweight of the samples taken before and after immersion:

C ¼Ww �Wd

Wd� 100ð%Þ ð1Þ

In the equation, Ww and Wd represent the weights of the seawa-ter-immersed sample and the dry sample, respectively. The seawa-ter content curve of basalt/CNT/epoxy multiscale composites isshown in Fig. 2, in which seawater uptake was plotted againstthe square root of immersion time. As can be seen in the figure,the seawater absorption of basalt/CNT/epoxy multiscale compos-ites was approximately Fickian and the seawater content at satura-tion was about 1.2% of the specimen weight. The diffusioncoefficient, D, was determined based on the Fick’s second law bymeans of the following equation:

MðtÞ ¼ Mð0Þ þ ðMð1Þ �Mð0ÞÞ4h

ffiffiffiffiffiffiDtp

rð2Þ

where M(0) is the initial amount of seawater in the specimen, M(1)the final amount at saturation, h the specimen thickness, and t theseawater-immersed time of the specimen. The diffusion coefficientwas 3.91 � 10�9 mm2/s.

Typical time–displacement curves of a basalt/CNT/epoxymultiscale composite are shown in Fig. 3. As shown in each graph,impact forces were transmitted to damping samples in approxi-mately 0.05 s. After impact, the remaining oscillations graduallydecreased with time. In the case of the sample not immersed inseawater, the residual oscillations lasted for approximately 2 s;

-1.0

-0.5

0.0

0.5

1.0

Dis

plac

emen

t (m

m)

time (sec)0.0 0.5 1.0 1.5 2.0

(a)

Fig. 3. Comparison of time–displacement curve for (a) dry and (b)

on the other hand, the oscillation from the sample which wasimmersed in seawater rapidly decreased within 1 s. To comparethe samples quantitatively, damping coefficients were determinedby calculating and averaging logarithmic ratios between adjacentoscillations of the time–displacement curve:

lnðxn=xnþ1Þ=p ð3Þ

In the equation, xn and xn+1 are peak displacement values. Thedamping coefficients of basalt/CNT/epoxy multiscale compositesare compared in Fig. 4. The damping coefficient of the sample whichwas not immersed in seawater was calculated as 0.0091 with astandard deviation of 0.00092. The value for the sample immersedin seawater was calculated to be 0.014 with a standard deviationof 0.0028, which is a 50% increase.

Vibrations of the basalt/CNT/epoxy multiscale compositeimmersed in seawater showed variation not only in terms ofdamping properties, but also in terms of frequency response. Thefrequency response functions of two types of composite samplesare compared in Fig. 5. The composite sample not immersed inseawater has a fivefold higher response than the sample immersedin the seawater. In addition, Fig. 5 shows that the position reso-nance frequencies are slightly different, 106.9 and 100.9 Hz forthe dry and seawater-saturated samples, respectively. The naturalfrequency of the cantilever decreased by approximately 6% byimmersion in seawater. This decrease can be understood basedon Meirovich’s continuous beam model [29]. In this theory, thenatural frequency of the first cantilever beam mode can be writtenas:

f ¼ 12p

1:875L

� �2ffiffiffiffiffiffiffiEIqA

sð4Þ

where L is the length of the beam, E is Young’s modulus, q is den-sity, and A and I are the cross-section’s area and moment of inertia.As the cross section is rectangular, the moment of inertia is I ¼ bd3

12and the area is A = bd, where b and d are the breadth and width ofthe beam cross-section. Assuming a rectangular cross section, theabove equation can be rewritten as f ¼ d

4ffiffi3p

p1:875

L

� �2ffiffiffiEq

q. From this

equation, it can be understood that decreases in the natural fre-quency can occur when either density is increased or Young’s mod-ulus is decreased. When density was measured, there was nodifference within the error bounds; the natural frequency decreaseis thus due to a decrease of Young’s modulus. The decrease ofYoung’s modulus was determined to be 25%. Additionally, we havechecked the validity of measurement and analysis. We have calcu-lated natural frequency of the cantilever using finite elementmethod based on the Young’s modulus obtained by Eq. (3). Whenthe calculated natural frequencies are compared with measure-ment, the calculated resonance frequency was within 0.5% of themeasured frequency.

0.0 0.5 1.0 1.5 2.0-1.0

-0.5

0.0

0.5

1.0

Dis

plac

emen

t (m

m)

time (sec)

(b)

fluctuation during impactremaining oscillation

seawater absorbed CNT/epoxy/basalt multiscale composites.

Dry specimen Seawater absorbed specimen0.000

0.005

0.010

0.015

0.020

Dam

ping

coe

ffici

ent

Fig. 4. Comparison of damping coefficient.

0 50 100 150 200 250 300 3500

1

2

3

4

5

Freq

uenc

y re

spon

se fu

nctio

n (m

m/N

)

Frequency (Hz)

Dry specimen seawater asorbed specimen

Fig. 5. Comparison of frequency response function.

Fig. 7. Comparison of n values in log–log scale.

Fig. 8. Comparison of Pcr as a function of crack length.

64 M.T. Kim et al. / Composites: Part B 63 (2014) 61–66

To measure fracture toughness via the compliance calibrationmethod using DCB samples, the compliance and fracture loadchanges must be determined as functions of crack length. Thiscan be determined from the load–displacement curves. TypicalP–d (P: load, d: load-point displacement) curves of dry andseawater-immersed basalt/CNT/epoxy multiscale composites areillustrated in Fig. 6. As can be seen in the figure, non-linear fracturebehavior was observed before the load reached its maximum level.

Fig. 6. Load–displacement curves of (a) dry and (b) seawa

It can also be seen that the remaining displacement was not negli-gible when the applied load returned to zero. The crack propagatedalong the initial crack plane (between the fourth and fifth layers);however, no fiber bridging occurred behind the crack tip. Fiber

ter absorbed CNT/epoxy/basalt multiscale composites.

Fig. 9. Comparison of GIc values as a function of crack length.

M.T. Kim et al. / Composites: Part B 63 (2014) 61–66 65

bridging did not occur because the basalt fibers are woven-typefibers.

The compliance changes with crack increase for dry and seawa-ter-absorbed basalt/CNT/epoxy multiscale composites were deter-mined from the P–d curves. Fig. 7 shows the variation incompliance with crack increase in a log–log scale for both compos-ites, in which ‘‘C’’ and ‘‘a’’ represent compliance and crack length,respectively. It can be seen from the figure that the difference incompliance between the two composites is not significant; how-ever, the compliance of the seawater-absorbed basalt/CNT/epoxysample is larger than that of the dry basalt/CNT/epoxy sample withthe same crack length. It can also be seen that there is a linear rela-tionship between logC and loga for each sample. The n00 valuesdetermined from the slopes of the dry and seawater-absorbed

Fig. 10. SEM images of fracture surfaces (a) dry and (c) seawater absorbed CNT/epoxy/barespectively.

basalt/CNT/epoxy multiscale composite plots were 2.48 and 2.15,respectively.

Fig. 8 shows changes in the fracture load Pcr during crackincrease for dry and seawater-absorbed samples. It can be seenin the figure that Pcr decreased as the crack length increased forboth composites; however, the Pcr of the seawater-absorbed sam-ple was smaller than that of the dry sample at the same cracklength, which is contrary to the compliance case. This indicatesthat the adhesion strength between the layers of basalt/CNT/epoxymultiscale composites was decreased by the seawater absorption.

Fracture toughness, GIc, was determined from the compliancecalibration method as follows:

GIc ¼nPcrd2ba

ð5Þ

where ‘‘b’’ is the sample width. Fig. 9 compares the variations in GIc

with crack length for dry and seawater-absorbed basalt/CNT/epoxymultiscale composites. The figure shows that, for both samples, thevalues of GIc vary in a limited range as the crack length increases.The figure also shows that the GIc values of the seawater-absorbedsamples were smaller than those of the dry samples with the samecrack length. The averaged GIc values for dry and seawater-absorbedCNT/epoxy/basalt multiscale composites were approximately0.7 kJ/mm2 and 0.4 kJ/mm2, respectively, indicating a �20% fracturetoughness decrease due to seawater absorption.

In order to investigate the fracture mechanism of basalt/CNT/epoxy multiscale composites due to seawater absorption, SEManalysis was performed on the fracture surfaces of dry and seawa-ter-absorbed basalt/CNT/epoxy multiscale composites after thefracture tests. Fig. 10a shows the fracture surface of the drybasalt/CNT/epoxy multiscale composites, while Fig. 10b shows amagnified image of the boxed region in Fig. 10a. It can be seen thatepoxy matrix was well adhered to the basalt fibers. The epoxy-richregion on the basalt fibers is a result of the homogeneous load sup-port of the basalt fibers due to the improved interfacial interactions

salt multiscale composites; (b), (d) are magnified images of boxed region in (a), (c),

66 M.T. Kim et al. / Composites: Part B 63 (2014) 61–66

of CNTs in the epoxy matrix. Fig. 10c shows the fracture surface ofthe seawater-absorbed basalt/CNT/epoxy multiscale composites,and Fig. 10d shows a magnified image of the boxed region inFig. 10c. Compared to the dry sample, more basalt fibers were frac-tured and some basalt fibers were removed from the epoxy matrix,showing the relatively clean surfaces. The figure also shows thatCNTs were partially pulled out from the epoxy matrix, whereaspartially removed CNTs were observed in the magnified image(indicated by arrows). The relatively clean surfaces of the basaltfibers were a result of the increased load transfer to the basaltfibers due to the poor interfacial interactions between the CNTsand the epoxy matrix. The GIc of seawater-absorbed basalt/CNT/epoxy multiscale composites was thus lower than that of dryCNT/epoxy/basalt multiscale composites.

4. Conclusions

In this study, the effect of seawater absorption on the vibrationdamping and fracture behaviors of basalt/CNT/epoxy multiscalecomposites was investigated. It was found that damping andfracture properties of basalt/CNT/epoxy multiscale compositesare significantly affected by seawater absorption. Specifically, thedamping coefficient of the composite sample was increased by50% after immersion in seawater. Compliance and fracture loadalso increased for a given crack length in the seawater-absorbedbasalt/CNT/epoxy multiscale composites. When basalt/CNT/epoxymultiscale composites fully absorbed seawater, fracture toughnessdecreased by �20%. The primary reason for the fracture toughnessdecrease of seawater-absorbed basalt/CNT/epoxy multiscale com-posites was a weakening of the interfacial bonding strengthbetween the basalt fibers and the epoxy as well as that betweenCNTs and the epoxy due to swelling of the epoxy matrix. Webelieve that the change of mechanical, vibrational propertiesshould be fully considered when applying basalt/CNT/epoxy multi-scale composites to structures, which are in contact with seawater.Temperature dependence of mechanical and vibrational propertiesof the composites is of great interest, and will be studied in thefuture.

Acknowledgement

This work was supported by a Grant from the Kyung Hee Uni-versity (Korea) in 2013 ‘‘(KHU-20130359)’’ and the Basic ScienceResearch Program through the National Research Foundation ofKorea (project number: 2013R1A1A2A10063466).

References

[1] Song YS. Multiscale fiber-reinforced composites prepared by vacuum-assistedresin transfer molding. Polym Compos 2007;28:458–61.

[2] Bekyarova E, Thostenson ET, Yu A, Kim H, Gao J, Tang J, et al. Multiscale carbonnanotube-carbon fiber reinforcement for advanced epoxy composites.Langmuir 2007;23:3970–4.

[3] Mei L, Li YB, Wang RG, Wang C, Peng QY, He XD. Multiscale carbon nanotube-carbon fiber reinforcement for advanced epoxy composites with highinterfacial strength. Polym Polym Compos 2011;19:107–12.

[4] Mohan TP, Kanny K. Effect of nanoclay in HDPE-glass fiber composites onprocessing, structure, and properties. Adv Compos Mater 2012;21:315–31.

[5] Silva F, Njuguna J, Sachse S, Pielichowski K, Leszczynska A, Giacomelli M. Theinfluence of multiscale fillers reinforcement into impact resistance and energyabsorption properties of polyamide 6 and polypropylene nanocompositestructures. Mater Des 2013;50:244–52.

[6] Sanchez M, Campo M, Jimenez-Suarez A, Urena A. Effect of the carbonnanotube functionalization on flexural properties of multiscale carbon fiber/epoxy composites manufactured by VARIM. Compos Part B – Eng2013;45:1613–9.

[7] Kim MT, Rhee KY, Lee JH, Hui D, Lau AKT. Property enhancement of a carbonfiber/epoxy composite by using carbon nanotubes. Compos Part B – Eng2011;42:1257–61.

[8] Ashrafi B, Guan JW, Mirjalili V, Zhang YF, Chun L, Hubert P, et al. Enhancementof mechanical performance of epoxy/carbon fiber laminate composites usingsingle-walled carbon nanotubes. Compos Sci Technol 2011;71:1569–78.

[9] Mahesh KRV, Murthy HNN, Kumaraswamy BE, Sridhar R, Krishna M, SherigaraBS. The influence of montmorillonite on mechanical, thermal and fireretardation properties of vinylester/glass composites. J Compos Mater2013;47:2163–78.

[10] Deák T, Czigány T, Tamás P, Németh CS. Enhancement of interfacial propertiesof basalt fiber reinforced nylon 6 matrix composites with silane couplingagents. eXPRESS Polym Lett 2010;4:590–8.

[11] Fiore V, Di Bella G, Valenza A. Glass–basalt/epoxy hybrid composites formarine applications. Mater Des 2011;32:2091–9.

[12] Kim MT, Kim MH, Rhee KY, Park SJ. Study on an oxygen plasma treatment of abasalt fiber and its effect on the interlaminar fracture property of basalt/epoxywoven composites. Compos Part B – Eng 2011;42:499–504.

[13] Lopresto V, Leone C, De Iorio I. Mechanical characterisation of basalt fibrereinforced plastic. Compos B: Eng 2011;42:717–23.

[14] Colombo C, Vergani L, Burman M. Static and fatigue characterisation of newbasalt fibre reinforced composites. Compos Struct 2012;94:1165–74.

[15] Lee JH, Rhee KY, Park SJ. The tensile and thermal properties of modified CNT-reinforced basalt/epoxy composites. Mater Sci Eng A 2010;527:6838–43.

[16] Kim MT, Rhee KY, Park SJ, Hui D. Effects of silane-modified carbon nanotubeson flexural and fracture behaviors of carbon nanotube-modified epoxy/basaltcomposites. Compos B: Eng 2012;43:2298–302.

[17] Xu L, Wang R, Zhang S, Liu Y. Vibration characteristics of glass fabric/epoxycomposites with different woven structures. J Compos Mater2011;45(10):1069–76.

[18] Suhr J, Koratkar N, Keblinski P, Ajayan P. Viscoelasticity in carbon nanotubecomposites. Nat Mater 2005;4(2):134–7.

[19] Fu SY, Feng XQ, Lauke B, Mai YW. Effects of particle size, particle/matrixinterface adhesion and particle loading on mechanical properties ofparticulate-polymer composites. Composites Part B 2008;39(6):933–61.

[20] Lau K, Leng J, Hui D, Rhee KY. Property enhancement of polymer-basedcomposites at cryogenic environment by using tailored carbon nanotubes.Composites Part B 2013;54(11):41–3.

[21] Kireitseu M, Hui D, Tomlinson G. Advanced shock-resistant and vibrationdamping of nanoparticle-reinforced composite material. Composites Part B2008;39(1):128–38.

[22] Azeez AA, Rhee KY, Park SJ, Hui D. Epoxy clay nanocomposites – processing,properties and applications: a review. Composites Part B 2013;45(1):308–20.

[23] Jia XL, Liu BY, Huang L, Hui D, Yang XP. Numerical analysis of synergisticreinforcing effect of silica nanoparticle-MWCNT hybrid on epoxy-basedcomposites. Composites Part B 2013;54:133–7.

[24] Wang ZX, Shen HS. Nonlinear vibration and bending of sandwich plates withnanotube-reinforced composite face sheets. Composites Part B2012;43(2):411–21.

[25] Latibari ST, Mehrali M, Mottahedin L. Investigation of interfacial dampingnanotube-based composite. Composites Part B 2013;50:354–61.

[26] Mahmoodi S, Nima J, Nader K, Siamak E. An experimental investigation ofnonlinear vibration and frequency response analysis of cantilever viscoelasticbeams. J Sound Vib 2008;311:1409–19.

[27] Mahmoodi SN, Khadem SE, Kokabi M. Non-linear free vibrations of Kelvin-Voigt visco-elastic beams. Int J Mech Sci 2007;49(6):722–32.

[28] ASTM D 5528-01: Standard test method for mode I interlaminar fracturetoughness of unidirectional fiber-reinforced polymer matrix composites.

[29] Meirovitch L. Analytical methods in vibration. London: Ccollier-MacMillanLtd.; 1967.