1. Vacuum infusion molding principle MSK 20120213

2. Vacuum bag infusion – step by step MSK 20120213

6. Vacuum bag infusion MSK 20120213

7. Vacuum infusion with semi-rigid shell MSK 20120213

8. MSK 2007-11-308 Careful resin flow rate regulation to avoid air entrapment RESIN FRONT VOIDS RESIN FLOW MSK 20120213

9. Resin infusion possibilities MSK 2007-11-309 From a centre point towards the periphery SLOWEST! MSK 20120213

10. Resin infusion possibilities MSK 2007-11-3010 From the edge MEDIUM FAST! MSK 20120213

11. Resin infusion possibilities MSK 2007-11-3011 Infusion from the pheriphery FASTEST! MSK 20120213

12. Flexible, semiflexible or rigid mould? Vacuum bag infusion (flexible bag): suitable for small production volumes, large size products and lower tolerance demands Vacuum infusion with semi-stiff shell: suitable for medium production volumes, medium product size and medium tolerance demands Vacuum infusion/RTM with stiff (solid) moulds: suitable for large production volumes, small size products and high tolerance demands MSK 2007-11-3012 MSK 20120213

13. Blades for wind mills Length 30 - 70 m 20 years life length Lay up of two separate halves which are glued together Filament winding Unsaturated polyester, vinyl ester, epoxy resin Glass fibre, carbon fibre Stiffness and fatigue properties are important Denmark major producer

14. MSK 20120213 Ambulance Polytec, Sweden

15. Modular construction design possible Parts are manufactured separately, and joined by adhesives MSK 20120213

16. Compression molding A premade compound is formed by pressure in a closed mold Crosslinking is initiated by heating Cost effective method for long and very long series SMC: sheet molding compounds BMC: bulk molding compounds Automotive and electrical industry most important application areas MSK 20120213

17. SMC manufacture Shelf life: 3 - 4 months MSK 20120213

18. SMC prepreg manufacture – step by step MSK 20120213

19. Application of resin onto plastic support film MSK 20120213

20. Addition of cut fibres MSK 20120213

21. Ready SMC is covered by second support film MSK 20120213

22. Schematic of compression molding MSK 20120213

23. SMC press MSK 20120213

24. Compression molding - process conditions Pressure:20-50 kg/cm 2 Temperature:145 - 160 ºC Time:1 - 5 minutes Molds:steel, chrome- plated MSK 20120213

25. Volvo V70 Tailgate Benefits with composite compared to steel: → Reduced tooling need → Styling freedom → Integration capability → Weight reduction compared to steel → Technology step

26. Comparison composite/metal series length MSK 20120213

27. V70 Tailgate Steel plate Theft/heat protection Reinforcement Directional fibres BMC t=3.5, 20% glass SMC t=2.5, 25% glass SMC t=2.5 (gen. Surfaces) 2.5- 4(stressed areas), 25% glass Glass fiber carpet M =10,3 kg (structure only)

28. Production volumes – manufacturing process MSK 20120213

29. Reinforcements MSK 20120213

30. Fibre types Glass fibre: relatively good strength, medium stiffness (E= 70 GPa), transparent, cheap Carbon fibres: very good strength, high stiffness (E=200-300 GPa), black, very expensive, electrically conducting Natural fibres: flax, hemp, sisal, wood Aramid fibres (Kevlar): very good tensile strength, yellow, hard to process, expensive Special fibres: polyethylene fibres, boron, ceramics, basalt

31. MSK 20120213 Fibres, yarns and rowings An assembly of collimated glass fibres is called a yarn, (tow, strand), and a group of yarns is called a rowing The yarns and rowings are twisted, which simplifies handling, but makes resin impregnation more difficult The fibre thickness varies typically between 3-25 µm (commonly 10-20 µm) Linear densities are given by the TEX number A rowing has a TEX of minimum 300

32. MSK 20120213 Characteristics for glass fibres Based on SiO 2 with added oxides of calcium, boron, sodium, iron or aluminium Depending on composition different glass types are defined: – A-glass (Alkali glass) – E- glass (Electrical glass) – C-glass (Chemically resistant glass) – S-glass (High strength glass) Characteristic properties are high strength, good tolerances for high temperatures and corrosive environments Transparency and no colour are advantages compared to other fibres Disadvantages are low stiffness, moisture sensitivity and abrasiveness Low cost has been the most critical factor when promoting their use

33. Composition and properties for glass fibres MSK 20120213 A glassC glassE glassS glass SiO 2 weight- % 7264,55565 Al 2 O 3 + Fe 2 O 3 weight-%244,525 CaO weight-%1013,521,5- MgO weight-%230,510 Na 2 O + K 2 O weight-%14,510< 1- B 2 O 3 weight- % -57,5 Tensile strength GPa3,13,33,64,6 Modulus GPa72707580 Softening point ºC700690850990 Density g/cm 3 2,45 2,542,48

34. Manufacturing process for carbon fibres MSK 20120213 Polyacrylonitrile (PAN) is the most common precursor for carbon fibres The strength of the fibres are due to orientation and stretching of the C-C bonds Strength can be increased by graphitisation at 1500 ºC

35. Carbon fibre production MSK 20120213

36. Textile reinforcements

37. MSK 20120213 Classification of reinforcements 1.Short 2.Unidirectional 3.2D weaves/Planar interlaced 4.3D/Fully integrated

38. MSK 20120213 Different reinforcement types Chopped strand mat Continuous strand mat Woven fabrics, diaxial Woven fabrics, multiaxial Stitched fabrics Braided fabrics Knitted fabrics Combinations

39. MSK 20120213 Chopped strand mats and continuous strand mats Non-woven structures Surface weights 150 - 900 g/m 2 Made from chopped or continuous yarns, bound together chemically, mechanically or by heating Emulsion binders and polyester powder binders are most common Good drapability Surface veils (surface eights 10-50 g/m 2 ) are used to get a wanted surface finish Mats made from other fibres are commonly named non-wovens

40. MSK 20120213 Woven fabrics = interlacing of 2 or more yarn systems Characterised by the crimp Lower crimp improves formability and resin permeability Crimp also reduces stiffness plain basket twill satin

41. MSK 20120213 Benefits with woven fabrics Good drapability Low manufacturing costs due to combination of two layers Good impact resistance Lower stiffness due to crimp Better compression strength

42. MSK 20120213 The mechanical properties for weaves depend on: Type of fibre Weave structure Stacking and orientation of fibres Yarn twist

43. MSK 20120213 Braided fabrics Circular braiding is used for tubes or ropes Biaxial Triaxial

44. MSK 20120213 Braided reinforcements MSK 2007-11-3044

45. MSK 20120213 Knitted fabrics Made by knitting Loose and flexible weaves are produced

46. MSK 20120213 Stitched fabrics (noncrimp) Fibre layers are stiched together into one structure The stiching is done by sewing Noncrimp fabrics offer a rapid and precise lay-up of multilayered reinforcement Different fibre types can be combined, sunh as comingled fabrics

47. Spread tow fabrics by Oxeon, Sweden MSK 20120213 Non-crimp fabric

48. MSK 20120213 Combinations Combination of different mats stitched together Ex: Combiflow mat: Porous flow layer for better mould filling, used in resin injection

49. MSK 20120213 Parabeam – 3 D fabric MSK 2007-11-3049

50. The interphase/interface in composites MSK 20120213

51. Long term durability of composites Depends on the state of the resin, which may undergo: – Physical ageing – Environmental degradation – Changes in fibre-matrix interaction – Matrix stress state, due to processing, thermal and fatigue cycling, mechanical loads Microcracking is the first sign of damage, which can initiate: – Fiber fracture – Interface debonding – Delamination The microcrack can be a pathway for moisture, chemicals, microorganisms, soil which then can lead to degradation MSK 20120213

52. Fibre-matrix interphase The three-dimensional boundry between the fiber and matrix It is critical for the control of composite properties, as fibre-matrix interaction occurs through the interface MSK 20120213

53. Interaction at fiber-matrix interface a)Micromechanical interlocking b)Electrostatic (dipole) interaction c)Chemical bonding d)Chain entangling e)Transcrystallisation MSK 20120213

54. Interphasial region in composites = the region of the matrix which is influenced by the fibre matrix fibre interphase Fibre diameter interface

55. Interphase in composites The interphase = a three dimensional region near the fiber with properties different compared to the fiber and the matrix MSK 20120213

56. Transversal fracture in composites Transversal fracture at low elongation (< 0.2%) due to poor adhesion between the fibre and the resin Transversal fracture at high elongation (> 0.6%) due to strong adhesion between the fibre and the resin MSK 20120213

57. Fibre surface treatments Surface oxidation; electrolytical, gases or liquid chemicals Surface coating by organic/inorganic chemicals (sizing agents) Polymer grafting onto fibre surface MSK 20120213

58. Surface treatment of glass fibres Surface treatment by sizeing Treatment composition: – Film forming polymer (PVA) – Lubricant – Coupling agent

59. Some effects due to surface treatment Fibre protection during shipment, handling and processing Binding of indivcidual filaments together to ensure easier handling Lubrication during processing Reduce static electricity Improve chemical bonding to the matrix MSK 20120213

60. Remark If the surface treatment is not properly done, it can be detrimental to the bulk mechanical properties, and the interface properties can vary MSK 20120213

61. 61 Non-destructive testing (NDT) For identification of defects without destroying the object Used for quality control and for in-service inspection Delaminations, failed adhesive bonds, voids, incorrect reinforcement orientation, variations in fiber content Based on differences in physical or mechanical properties, due to the defect Comparative methods -> qualitative information

62. MSK 20120213 62 Ultrasonic inspection Transmission of sound waves through the specimen 0.5 - 75 MHz sound Pulse-echo or through transmission Coupling mediums (water, oil, gels) for efficient transfer of sound wave into the component NDT methods

63. MSK 20120213 63 Acoustic emission Detection of microscopic failures by recording the sound of the event Fiber fractures and matrix microcracks In combination with mechanical loading Semi-NDT Careful interpretation of data necessary NDT methods

64. MSK 20120213 64 Acoustic emission

65. MSK 20120213 65 Other methods Radiography (X-ray,  -ray) Computer aided tomography: defects can be located Thermographic inspection: based on differences in thermal diffusivity Vibrational inspection: ¨coin tapping¨ NDT methods

66. End of part 2 MSK 20120213