资源描述
Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,*,*,Effect of vibrations on void content in composite materials,Jelena Muric,-,Nesic,Supervisors:P.,Compston,N.Noble,Z.,Stachurski,DERF June 2008.,2,/16,Presentation Overview,Project to date,aim,method,results,discussion,Current work,Future,Conclusions,Vibration Project,Jelena MN,Vibrations,3,/16,Projects Aim,What?,Good quality laminates,Better mechanical properties,Minimize defects,Bubbles,fibre,wetting,Void content 2%,How?,Vibrations:,Suitable frequency,Mode of vibration,Position,Transmission means,Vibration Project,Jelena MN,4,/16,Projects Method I,Shaker,1-9000 Hz,signal generator,power amplifier and mould,Hand,lay-up of glass fibres(12 plies)and vinyl-ester resin,Laminates(10 x10 x3mm),UV curing,Optical microscope,Top cover&Vacuum-later,Vibration Project,Jelena MN,5,/16,Projects Method II,Changing Parameters,Frequency and power of vibrations,Time length,Temperature,Top cover plate,Vacuum bagging,Hypothesis,Void mobility,Stokes law,Viscosity(,Arrhenius,),Energy-Amplitude:,EA,2,Pressure:PV=RT,Vibration Project,Jelena MN,.,Whats happening?!,Pressure and temperature variations internal pressure-external pressure=2,/r,Buoyancy,Coalescence/dispersion of voids,6,/16,Vibration Project,Jelena MN,Expansion,Shrinkage,-,surface tension of a liquid,r,-radius of a bubble,7,/16,Projects Results I,Optical micrograph(64x),Void sizes:,500,m,_ 100m,Vibration Project,Jelena MN,Distribution of bubble size cross section,8,/16,Projects Results II,10 min,30 min,Vibration Project,Jelena MN,A.,50 100,m,B.,100 200,m,C.,200 500,m,D.,500,m,9,/16,Projects Results III,Vibration Project,Jelena MN,A.,50 100,m,B.,100 200,m,C.,200 500,m,D.,500,m,10,/16,Projects Discussion I,Void percentage observed on 8 images of each laminates cross-section,No cover,%,Top cover,%,+vacuum,%,10,1.005,0.477,0.104,30,2.124,0.040,0.018,50,5.656,1.076,0.543,NO,8.374,4.502,1.363,Frequency,Hz,Vibration Project,Jelena MN,11,/16,Projects Discussion II,Good results from:,Low freq(10-50Hz),Higher temperatures,Top cover,Vacuum,Void%decreased,Properties still to investigate,Is it good enough?,Can it be better?,Vibration Project,Jelena MN,Hot water tanks,50l,Pump,Water pot,Flexible hoses,Shakers,Lower chamber,Upper chamber,Silicone membrane,Schematic of the system,Current Work,Small machine?!?,With vibrations,Curing at elevated temperatures(80C),Heat transfer rate liquid/gas=25,Vacuum,Epoxy resin system,Vibration Project,Jelena,MN,13,/16,14,/16,Future,Low frequencies,High temperatures,Vacuum,Different,fibre,/resin,1 to 5 shakers,Optical microscopy and CT scan,Mechanical testing,Vibration Project,Jelena MN,15,/16,Conclusions,Vibrations reduce void content(bubbles),Reduced void%leads to improved laminate quality,Vibration Project,Jelena MN,Effect of vibrations on void content,in composite materials,DERF June 2008.,Jelena Muric-Nesic,Supervisors:P.Compston,N.Noble,Z.Stachurski,Thank you!,
展开阅读全文