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Aru Shukla - One of the best experts on this subject based on the ideXlab platform.
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EffEct of polyurEa coatings on thE rEsponsE of curvEd E Glass vinyl EstEr compositE panEls to undErwatEr ExplosivE loading
Composites Part B-engineering, 2013Co-Authors: James Leblanc, Nate Gardne, Aru ShuklaAbstract:Abstract ThE EffEcts of polyurEa coatings on thE rEsponsE of E-Glass/Vinyl EstEr curvEd compositE panEls subjEctEd to undErwatEr ExplosivE loading has bEEn studiEd. ThE thicknEss and location of thE polyurEa coating has bEEn variEd to dEtErminE how thEsE paramEtErs affEct thE transiEnt rEsponsE. ThE compositE matErial is a 0°/90° biaxial layup and thE coatings arE appliEd to EithEr thE loadEd or non-loadEd facEs. ThE currEnt work utilizEs a conical shock tubE facility which producEs shock loading conditions EquivalEnt to thE undErwatEr dEtonation of an ExplosivE chargE. ThE transiEnt rEsponsE of thE platEs is rEcordEd using a thrEE-dimEnsional (3D) Digital ImagE CorrElation systEm, consisting of high-spEEd photography and spEcializEd post procEssing softwarE. ThE rEsults show that for a givEn polyurEa thicknEss, bEttEr pErformancE is obtainEd whEn thE back facE of thE panEl is coatEd. Similarly thE pErformancE is improvEd as thE coating thicknEss is incrEasEd; howEvEr this comEs at a cost in tErms of incrEasEd arEal wEight. ThE rEsults show that thErE is likEly an optimal coating thicknEss, that whEn locatEd on thE back facE, providEs a balancEd tradEoff bEtwEEn panEl pErformancE and wEight incrEasE.
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shock loading rEsponsE of sandwich panEls with 3 d wovEn E Glass compositE skins and stitchEd foam corE
Composites Science and Technology, 2009Co-Authors: Srinivasan Arju Tekalu, Alexande E Ogdanovich, Aru ShuklaAbstract:Sandwich compositE arE usEd in numErous structural applications, with dEmonstratEd wEight savings ovEr convEntional mEtals and solid compositE matErials. ThE incrEasing usE of sandwich compositEs in dEfEnsE structurEs, particularly thosE which may bE ExposEd to shock loading, dEmands for a thorough undErstanding of thEir rEsponsE to suc highly transiEnt loadings. In ordEr to fully utilizE thEir potEntial in such ExtrEmE conditions, dEsign optimization of thE skin and corE matErials arE dEsirablE. ThE prEsEnt study is pErformEd for a novEl typE of sandwich matErial, TRANSONITE madE by pultrusion of 3-D wovEn 3WEAVE E-Glass fibEr compositEs skin prEforms intEgrally stitchEd to polyisocyanuratE TRYMER TM 200L foam corE. ThE EffEct of corE stitching dEnsity on thE transiEnt rEsponsE of thrEE simply supportEd sandwich panEls loadEd in a shock tubE is ExpErimEntally studiEd in this work. ThE ExpErimEntal program is focusEd on rEcording dynamic transiEnt rEsponsE by high-spEEd camEra and post-mortEm Evaluation of impartEd damagE. ThE obtainEd ExpErimEntal rEsults rEvEal nEw important fEaturEs of thE transiEnt dEformation, damagE initiation and progrEssion and final failurE of sandwich compositEs with unstitchEd and stitchEd foam corEs. ThE thEorEtical study includEs full 3-D dynamic transiEnt analysis of displacEmEnt, strain and strEss fiElds undEr ExpErimEntally rEcordEd surfacE shock prEssurE, pErformEd with thE usE of 3-D MOSAIC analysis approach. ThE obtainEd thEorEtical and ExpErimEntal rEsults for thE transiEnt cEntral dEflEctions in unstitchEd and two stitchEd foam corE sandwichEs arE mutually comparEd. ThE comparison rEsults rEvEal largE discrEpanciEs in thE casE of unstitchEd sandwich, much smallEr discrEpanciEs in thE casE of intErmEdiatE stitching dEnsity, and ExcEllEnt agrEEmEnt bEtwEEn thEorEtical and ExpErimEntal rEsults for thE sandwich with thE highEst stitching dEnsity. ThE gEnEral conclusion is that furthEr comprEhEnsivE ExpErimEntal and thEorEtical studiEs arE rEquirEd in ordEr to gEt a thorough undErstanding of a vEry complEx bEhavior of compositE sandwichEs undEr shock wavE loading.
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mEchanical bEhavior and damagE Evolution in E Glass vinyl EstEr and carbon compositEs subjEctEd to static and blast loads
Composites Part B-engineering, 2008Co-Authors: Srinivasan Arju Tekalu, Kunigal N Shivakuma, Aru ShuklaAbstract:FibEr basEd compositEs havE found ExtEnsivE applications in various fiElds. In this study, two diffErEnt fibEr matErials, namEly, E-Glass and carbon, with diffErEnt architEcturE arE chosEn. PolymEr (vinyl EstEr) basEd compositEs wErE dEsignEd using thEsE fibErs and wErE fabricatEd using VARTM procEss. ThEsE compositEs wErE subjEctEd to quasi-static and high strain ratEs of loading utilizing diffErEnt tEsting mEthodologiEs. In quasi-static tEsting, thE tEnsilE, comprEssivE and shEar propErtiEs wErE studiEd using Existing ASTM standard tEsting procEdurEs and thE rEsults arE rEportEd. ThE carbon compositE showEd highEr tEnsilE and comprEssivE modulus. In-planE shEar propErtiEs of both thE compositEs wErE comparablE and intEr laminar shEar propErtiEs of E-Glass compositEs wErE obsErvEd to bE bEttEr than thE carbon compositE bEcausE of thE bEttEr nEsting bEtwEEn thE E-Glass fabric layErs. A shock tubE and a controllEd Explosion tubE wErE utilizEd in thE study of dynamic damagE bEhavior of thEsE compositE matErials. BasEd on thE ExpErimEntal study, it is obsErvEd that thE carbon fibEr compositEs tEnd to achiEvE suddEn dEstructivE damagE whErEas E-Glass fibEr compositEs tEnd to sustain progrEssivE damagE, undEr dynamic loading.
M Kumosa - One of the best experts on this subject based on the ideXlab platform.
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an Evaluation of thE critical conditions for thE initiation of strEss corrosion cracking in unidirEctional E Glass polymEr compositEs
Composites Science and Technology, 2001Co-Authors: L Kumosa, D Armentrou, M KumosaAbstract:ThE purposE of this work is to Establish thE critical surfacE conditions lEading to thE initiation of strEss-corrosion cracks on thE as-suppliEd surfacEs of thrEE unidirEctional E-Glass/polymEr compositEs with modifiEd polyEstEr, Epoxy and vinyl EstEr rEsins subjEctEd to a nitric acid solution without mEchanical loads. ThE compositE matErials considErEd in this study arE commonly usEd in compositE high-voltagE insulators on ovErhEad transmission linEs with thE linE voltagEs ranging from 69 to 735 kV. ThE initiation of strEss-corrosion cracks in ExposEd Glass fibErs on thE compositE surfacEs was obsErvEd in thE absEncE of ExtErnally appliEd mEchanical loads. HowEvEr, thE crack initiation ratEs arE strongly dEpEndEnt on thE amount of ExposEd fibErs. AftEr thE initial stagE of crack initiation, no furthEr strEss-corrosion damagE is obsErvEd in thE compositEs. ThE E-Glass/vinyl EstEr systEm appEars to bE morE rEsistant to thE initiation of strEss-corrosion cracking in comparison with thE othEr two compositE systEms invEstigatEd. This systEm Exhibits thE lowEst numbEr of strEss-corrosion cracks and thE lowEst total surfacE arEa of ExposEd fibErs on thE compositE surfacEs. ThE E-Glass/Epoxy compositE shows thE lowEst rEsistancE to strEss corrosion with thE largEst arEas of ExposEd fibErs. ThE EffEct of ExposEd fibErs on thE strEss-corrosion procEss in unidirEctional E-Glass/polymEr compositEs usEd in high voltagE insulators has not bEEn prEviously rEportEd. It is clEar that in ordEr to rEducE thE ratEs of failurE of compositE high-voltagE insulators by strEss-corrosion cracking (brittlE fracturE), thE prEsEncE of ExposEd fibErs on thEir rod surfacEs should bE minimizEd.
Mahmood M. Shokrieh - One of the best experts on this subject based on the ideXlab platform.
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EffEct of initial crack lEngth on thE mEasurEd bridging law of unidirEctional E Glass Epoxy doublE cantilEvEr bEam spEcimEns
Materials & Design, 2014Co-Authors: Mahmood M. Shokrieh, Mazaher Salamattalab, M HeidariraraniAbstract:Abstract In this papEr, thE EffEct of initial dElamination lEngth is ExpErimEntally invEstigatEd on obtaining thE modE I bridging law of unidirEctional E-Glass/Epoxy doublE cantilEvEr bEam (DCB) spEcimEns manufacturEd by hand layup mEthod. To this End, an ExpErimEntal tEst sEt-up is EstablishEd for accuratE mEasurEmEnt of crack tip opEning displacEmEnt (CTOD) using digital imagE procEssing mEthod. DCB tEsts arE pErformEd for thrEE diffErEnt dElamination lEngths and thE corrEsponding bridging laws arE calculatEd using J -intEgral approach. REsults showEd that thE maximum bridging strEss, thE shapE of bridging law and EnErgy dissipation in bridging zonE arE slightly affEctEd by changing initial crack lEngth. In othEr words, thE mEasurEd bridging law acts indEpEndEnt of initial dElamination lEngth. ThErEforE, thE obtainEd bridging law can bE usEd with thE cohEsivE ElEmEnts availablE in thE commErcial finitE ElEmEnt softwarE to simulatE thE dElamination propagation bEhavior in unidirEctional DCB spEcimEns.
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corrosion bEhaviour and crack formation mEchanism of basalt fibrE in sulphuric acid
Corrosion Science, 2012Co-Authors: V Nasir, Fathollah Taheribehrooz, Hadis Karimipour, Mahmood M. ShokriehAbstract:Abstract In this invEstigation, thE corrosion bEhaviour and crack formation mEchanism of thE basalt fibrE ExposEd to sulphuric acid wErE studiEd. For this purposE, diffErEnt points of thE fibrE surfacE wErE ExaminEd by SEM and EDX mEthods to Explain thE corrosion bEhaviour and lEaching of non-silicEous ions from thE fibrE surfacE. ThE fracturE mEchanism of thE basalt fibrE showEd that thE spiral and axial cracks wErE gEnEratEd at thE highEr ExposurE timEs in comparison with thE E-Glass fibrE. ThE study on thE strEngth bEhaviour of thE basalt fibrE also rEvEalEd that thE strEngth dEgradation of thE E-Glass fibrE was morE sEvErE than that of thE basalt fibrE.
Murat E Sozer - One of the best experts on this subject based on the ideXlab platform.
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compaction of E Glass fabric prEforms in thE vacuum infusion procEss a usE of charactErization databasE in a modEl and b ExpErimEnts
Journal of Composite Materials, 2013Co-Authors: Bekir Yenilmez, Murat E SozerAbstract:Compaction of E-Glass fabric prEforms (random, wovEn and biaxial) EmbEddEd with a distribution mEdium (polypropylEnE) is couplEd with 1D rEsin (polyEstEr) flow during initial application of vacuum,...
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compaction of E Glass fabric prEforms in thE vacuum infusion procEss a charactErization ExpErimEnts
Composites Part A-applied Science and Manufacturing, 2009Co-Authors: Bekir Yenilmez, Murat E SozerAbstract:An ExpErimEntal procEdurE was dEsignEd to rEalistically charactErizE thE compaction bEhavior of E-Glass fabric prEforms during initial application of vacuum and mold filling stagEs of Vacuum Infusion (VI). To mimic VI, thE loading (compaction) was donE on a dry prEform, and thE unloading (dEcompaction) was donE aftEr thE prEform was saturatEd with rEsin. WhEn fabrics wErE wEttEd at constant full compaction prEssurE, a significant dEcrEasE in thicknEss was obsErvEd for thE random fabric, but not for wovEn and biaxial fabrics. ThE ratE of changE of thicknEss, ∂h/∂t had diffErEnt signs and ordEr of magnitudEs whEn various constant compaction prEssurEs wErE appliEd during fibEr rElaxation stagE. Thus, prEvious compaction-mold filling modEls basEd on static rElationship bEtwEEn thicknEss and compaction prEssurE do not appropriatEly simulatE thE compaction physics of VI. TimE-dEpEndEnt databasE of this study is a usEful and straightforward tool to modEl VI, as dEmonstratEd in Part B of this study.
L Kumosa - One of the best experts on this subject based on the ideXlab platform.
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an Evaluation of thE critical conditions for thE initiation of strEss corrosion cracking in unidirEctional E Glass polymEr compositEs
Composites Science and Technology, 2001Co-Authors: L Kumosa, D Armentrou, M KumosaAbstract:ThE purposE of this work is to Establish thE critical surfacE conditions lEading to thE initiation of strEss-corrosion cracks on thE as-suppliEd surfacEs of thrEE unidirEctional E-Glass/polymEr compositEs with modifiEd polyEstEr, Epoxy and vinyl EstEr rEsins subjEctEd to a nitric acid solution without mEchanical loads. ThE compositE matErials considErEd in this study arE commonly usEd in compositE high-voltagE insulators on ovErhEad transmission linEs with thE linE voltagEs ranging from 69 to 735 kV. ThE initiation of strEss-corrosion cracks in ExposEd Glass fibErs on thE compositE surfacEs was obsErvEd in thE absEncE of ExtErnally appliEd mEchanical loads. HowEvEr, thE crack initiation ratEs arE strongly dEpEndEnt on thE amount of ExposEd fibErs. AftEr thE initial stagE of crack initiation, no furthEr strEss-corrosion damagE is obsErvEd in thE compositEs. ThE E-Glass/vinyl EstEr systEm appEars to bE morE rEsistant to thE initiation of strEss-corrosion cracking in comparison with thE othEr two compositE systEms invEstigatEd. This systEm Exhibits thE lowEst numbEr of strEss-corrosion cracks and thE lowEst total surfacE arEa of ExposEd fibErs on thE compositE surfacEs. ThE E-Glass/Epoxy compositE shows thE lowEst rEsistancE to strEss corrosion with thE largEst arEas of ExposEd fibErs. ThE EffEct of ExposEd fibErs on thE strEss-corrosion procEss in unidirEctional E-Glass/polymEr compositEs usEd in high voltagE insulators has not bEEn prEviously rEportEd. It is clEar that in ordEr to rEducE thE ratEs of failurE of compositE high-voltagE insulators by strEss-corrosion cracking (brittlE fracturE), thE prEsEncE of ExposEd fibErs on thEir rod surfacEs should bE minimizEd.