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چكيده انگليسي :

Investigation in to energy absorption capacity of composites reinforced by 3D weft knitted fabric Reza Hessami r hessami@tx iut ac ir Textile Engineering Department December 2010 Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisor Hosien Hasani h hasani@cc iut ac ir AbstractEnergy absorption capacity is one of the most important criterion in selecting materials for many engineeringapplications such as crushing elements in cars bicycle helmets hard hats use construction sites andprotective packaging of fragile goods the materials or devices used as impact energy absorbers should utilizethe plastic deformation as major energy absorbing mechanism In addition a light weight would be anattractive attribute in their applications Despite the use of 2D laminates over a long period their use in manystructural applications has been limited by manufacturing problems and some inferior mechanical properties The manufacturing of laminates can be expensive because of the high labor cost in the manual lay up ofplies Added to these costs is the poor drape of many prepreg and fabric plies which makes them difficult tomould in to complex shapes The problem added to this is the lack of through the thickness reinforcement orpoor interlaminar fracture toughness results low resistance to delamination In an attempt to overcome manyof the problems with the manufacturing and mechanical properties of laminates considerable attention hasbeen given over the past 30 years to the development of advanced polymer composites reinforced with 3Dfiber architectures Composite structures made from 3D textile fabrics are potentially less expensive tomanufacture and provide better through the thickness mechanical properties than composites made with thetraditional 2D fabrics Particularly attractive of 3D dimensional textile performs are improved damagetolerance and the benefit of near net shape cellular manufacturing The most attention has been given to 3Dcomposites manufactured by the textile techniques of weaving braiding stitching and knitting Knitting isparticularly well suited to the rapid manufacture of components with complex shapes due to the lowresistance to deformation of knitted fabrics Knitted fabric composites shows a better delamination resistanceand more absorbed impact energy compared to woven fabric composites In this project two kind of knitted structures simple single jersey plain and double jersey rib with twodensity high and low of textured multi filament nylon 150 deneir were knitted The fabric was placed on theplate include geometric dimensions truncated cone and hemisphere with both low and high density Anotherdrilled page was placed on fabric in such a manner that the fabric was clamped between two plates by bolts inaround of plates Then this set was placed in oven with temperature 180 C and duration of 5 minutes andthermoforming action was ran Three dimensional fabric was covered by the epoxy resin Then to achieve anideal energy absorbing resin covered three dimensional fabric was placed in a polymer substrate PVC foamis suitable for this was selected The foam energy absorber to achieve an ideal state should have elastic andthus the foaming agent was applied The exact amount of PVC and foaming agent plus precise determinationprocessing factors such as temperature and curing time was achieved The specimen was prepared by standardmould that the three dimensional fabric was placed in between of the mould Then the PVC foam with thesame amount was poured in to the mould on both sides of the fabric Then the mould was placed in the ovenwith specific heat and time Specimens based on the Taguchi L8 design test method was prepared and thequasi static tensile and pressure and dynamic impact Drop weight tests were ran Results of the mini tabsoftware was analyzed and optimized sample among the samples the sample reinforced by the structure ofhigh density rib with high density truncated con showed the highest str

حسامي، رضا

بررسي ظرفيت جذب انرژي در كامپوزيت هاي تقويت شده با پارچه هاي حلقوي پودي سه بعدي

فوم پي وي سي , كامپوزيت پليمري