Examples of composites. Composited in nature wood bones. Syntetic composites Plywood Paper Metallic alloys Reinforced concrete

Transcription

1 MTY-7-EN Composites

2 Examples of composites Composited in nature wood bones Syntetic composites Plywood Paper Metallic alloys Reinforced concrete

3 Advantages and disadvantages of composites Advantages High ratio between strength and stiffness to density High resistance against creep and fatigue High strength at high temperatures High toughness Resistivity to corrosion Anisotropy Disadvantages Expensive materials Expensive manufacturing Hard to repair Material properties Anisotropy Complex testing of properties and inspection

4 Principle of composite Two or more components are combined in such a way that the properties of the resulting material cannot be obtain from one homogeneous material

5 High-tech application of composites

6 Composites in sport and luxury goods

7 Phases of composites Matrix - continuous Reinforcement discrete Metals Ceramics Composites Polymers Glasses

8 Composite materials Composites particulate fibrous Structural Large p. dispersion Long fiber Short fiber laminates sandwich oriented random

9 Composites:isostress a isostrain Reuss Density C V a a V b b E eff 1 Reuss V E a a V E b b Voigt Modulus (bounds) E Voigt eff V a E a V b E b

10 Elastic moduli of long-fibre composites

11 Mechanical properties of long-fibre composite

12 Mechaniccal properties of composites Upper bond Lower

13 Strength of composites fiber fiber composite matrix composite matrix

14 Strength of fiber reinforced material

15 Anisotropy of unidirectional fiber-reinforced layer

16 Laminates - notation Lamina orientation [0/45/-45/90] Symmetry [0/90/0] s = [0/90/0/0/90/0] Layers repetition [0/90 3 /45] = [0/90/90/90/45] Material indication [0G/0C/90C/90K] Glass, Carbon, Kevlar Quasi isotropy Symmetry

17 Sandwich

18 Short-fiber composite

19 Short fibred composites

20 Short fiber composites fiber orientation

21 Relation of fiber strength to its diameter Comparison of bulk and fiber strength of selected materials Material Elasticity modulus E [GPa] Strength in tension R m [MPa] Glass fiber type E to Glass E Carbon fiber 190 to to Polycrystalline graphite Ceramic fiber SiC bulk SiC Polyethylene fiber UHMW PE 80 to

22 Fiber materials Polymeric material density ϱ (g.cm -3 ) R(MPa) E(GPa) Elongation A (%) Syntethic wood 1, , celullose (Fortisan) 1, ,4 --- polyester (Terylen) 1, ,2 --- polyamide (Nylon) 1, ,9 --- aramide (Kevlar 29) 1, ,6 4,0 aramide (Kevlar 49) 1, ,0 2,5 aramide (Kevlar 149) 1, ,0 1,5 aramide (Twaron) 1, ,0 3,3 aramide (Twaron HM) 1, ,0 2,3 Ceramic Material Density ϱ (g.cm -3 ) Rm (MPa) E (GPa) Fiber diameter (µm) Thermal stability ( C) Al 2 O 3 3,15 to 4, to to ZrO 3 4, carbon 1,6 to 2, to to to BN 1, to to to B 4 C 2,3 to 2, to to

23 Carbon fibres Carbon fiber property at room temperature Property Hi-modulus graphite Hi-strength graphite steel (pcomparison) density ϱ [g.cm -3 ] 1,90 1,90 7,8 Young modulus of elasticity E [GPa] Strength R m [GPa] 2,1 2,5 0,34 to 2,1 Effective modulus E/ϱ [MPa.g -1.cm 3 ] ,9 Effective strength R m /ϱ [MPa.g -1.cm 3 ] 1,1 1,3 0,043 to 0,27

24 Materials of fibres

25 Matrix Materials Polymeric Thermosets (Epoxides) Thermoplastic matrix (Polyetheretherketone (PEEK), Polyfenylensulfide (PPS)) Metallic Copper Sintered carbides Cermets Ceramic SiC whiskers / Al2O3 matrix SiC whiskers / Si3N4 matrix SiC / SiC matrix Fiber / glass matrix Carbon / carbon composites

26 Synergic effect Rule of mixtures: P RoM = P 1 f 1 + P 2 f 2 (f1 + f2 = 1) Synergy P observed >>> P RoM Fracture toughness: glass U~ 1 J/m 2, polyester U~ J/m 2 Rule of mixtures U~ J/m 2 but... Observed U~ J/m 2!! WHY???

27 Interface - wetting

28 Interaction between fracture and composite

29 Fracture toughness of composites -Plastic deformation of matrix in vicinity of crack -Crack changes direction in contact with fiber (not perpendicular to force) -Energy to separate fiber from matrix -Pull/out of fibers from matrix - friction

30 Comparison of composites and other classes of materials

31 Testing of composite materials Elastic properties (4 independent values) Modulus of elasticity in direction of fibers Modulus of elasticity in perpendicular direction to fibers Shear modulus Poisson ratio Strength properties (5 independent values) In direction of fibers tension and compression In direction perpendicular to fibers tension and compression Shear strength

32 Manufacturing of composites prepregs

33 Manufacturing of composites autoclave

34 Manufacturing and joining of composites lepení

35 Thank you for your attention!