Vibrations and voids in compositesVibrations and voids in compositesDERF, ANU, Jun 2007DERF, ANU, Jun 2007

JelenaJelena MuricMuric--NesicNesic

Supervisors:Supervisors:P.P.CompstonCompston, N.Noble, Z., N.Noble, Z.StachurskiStachurski

Presentation overviewPresentation overview

Project aimsProject aimsPrevious researchPrevious researchExperiments and resultsExperiments and resultsPlansPlans

Project aimsProject aims

Defects: Defects: 1.1. Entrapped airEntrapped air2.2. Poor fibre wetting Poor fibre wetting 3.3. Fibre distortionFibre distortion

HypothesisHypothesisoo Suitable frequencySuitable frequencyoo Mode of vibrationMode of vibrationoo PositionPositionoo Transmission meansTransmission means

Improving the quality of composite materials Improving the quality of composite materials cured by Quickstep methodcured by Quickstep method

Previous researchPrevious research““Effects of low frequency vibration processing Effects of low frequency vibration processing

on carbon/epoxy laminateson carbon/epoxy laminates””S.R.S.R.GhiorseGhiorse and R.M.and R.M.JurtaJurta Composites, No 1, Jan 1991.Composites, No 1, Jan 1991.

Vibration assisted vacuum composite procVibration assisted vacuum composite procLow freq (40Low freq (40--50Hz)50Hz)2.5 h at 1202.5 h at 120°°--180180°°CC50% decreased void content50% decreased void content10% increased void size10% increased void size0.5% increased density0.5% increased density

Experiments and resultsExperiments and results

1.1. Piezoelectric Piezoelectric transducer 40 kHztransducer 40 kHz

2.2. Shaker 1Shaker 1--9000 Hz, 9000 Hz, with signal generator with signal generator and power amplifierand power amplifier

oo Hand layHand lay--up of glass up of glass fibres and vinylfibres and vinyl--ester ester resin (UV curing)resin (UV curing)

LaminatesLaminatesChanging Parameters:Changing Parameters:

Frequency and power of Frequency and power of vibrations (2vibrations (2--40,000Hz)40,000Hz)Time interval of Time interval of vibrations (vibrations (10min)10min)Temperature (Temperature (2020--45C)45C)Amount of Amount of fibresfibres ((44--12 12 layers)layers)

Cut and polishedCut and polished

MicroscopesMicroscopes

Scanning Electron MicroscopyScanning Electron Microscopy

10Hz

8kHz

4Hz

Voids at 40kHz Voids at 40kHz -- 4Hz4Hz

μμmmAA < 50< 50BB 5050--100100CC 100100--200200DD 200200--500500EE > 500> 500

room temperature 45C

0

2

4

6

8

10

12

frequency, Hz

bubb

le c

ount

no 40,000 8,000 100 4 4

More parameters to alterMore parameters to alter

Frequency, power Frequency, power and position of vibrations and position of vibrations How many vibration centers for specific area How many vibration centers for specific area Mode of vibrations (slowMode of vibrations (slow--up/quickup/quick--down)down)TemperatureTemperature

PlansPlans

Currently working with 10Currently working with 10--50Hz50HzHigh frequency (MHz range) for wavelength High frequency (MHz range) for wavelength going through a laminate or to be the size of a going through a laminate or to be the size of a bubble (0.05bubble (0.05--3mm)3mm)QS mould is closed systemQS mould is closed systemNew approachNew approach

Vibrations and voids in compositesVibrations and voids in compositesDERF, ANU, Jun 2007DERF, ANU, Jun 2007

JelenaJelena MuricMuric--NesicNesic

Supervisors:Supervisors:P.CompstonP.Compston, N.Noble, , N.Noble, Z.StachurskiZ.Stachurski