Prüfmethoden zur Charakterisierung von Verbundwerkstoffen

Transcription

1 Prüfmethoden zur Charakterisierung von Verbundwerkstoffen Gerald Pinter 1), Markus Wolfahrt 2) 1) Institut für Werkstoffkunde und Prüfung der Kunststoffe Montanuniversität Leoben, A 2) Polymer Competence Center Leoben GmbH, Leoben, A Zukunft der Faserverbundwerkstoffe in der österreichischen Luftfahrtindustrie und -forschung, Wien 1. Dezember 2008

2 Introduction Failures in Composites Composite- Component (CFK) Metall-Structure Composite-Structure (GFK) 2

3 Scientific concept and methodology I The Pyramid of Tests High Performance Composites FACC AG, A FACC AG, A full scale tests detail and sub-component test standardized test specimens (laminates) constituent characterization application simulation special laminate tests damage tolerance fatigue etc tensile/compression tests shear tests basic fracture mechanics (DCB, ENF) analytical,spectroscopical methods microscopy mechanical, thermomechanical tests 3

4 Aircraft Certification of Composites Qualification Testing and Costs The Pyramid of Tests Full-Scale Component Tests 70 % Vertical stabilizer A310/A320 First source qualification Subcomponent Tests Detail Tests Coupon/Element Tests 13 % Relative Costs 3 % 14 % General Problem Lack of knowledge of interactions and correlations of different tests within and between the various levels of the test pyramid Source: K. Schneider and R.W. Lang (Europ. SAMPE Symp., 1990) 4

5 Scientific concept and methodology II Material properties, material models/laws Design geometry model material (pre)selection Input data Component simulation phenomenological models micro-structure based models feed-back loop Component testing load deformation and strain component temperature failure Tailored and Safe Components 5

6 Scientific concept and methodology I The Pyramid of Tests High Performance Composites FACC AG, A FACC AG, A full scale tests detail and sub-component test standardized test specimens (laminates) constituent characterization application simulation special laminate tests damage tolerance fatigue etc tensile/compression tests shear tests basic fracture mechanics (DCB, ENF) analytical,spectroscopical methods microscopy mechanical, thermomechanical tests 6

7 The Pyramid of Tests Constituent characterization Light and Scanning Electron Microscopy Fracture surface of delaminated specimen (SEM) Specimen after ILSS test (LM) 7

8 The Pyramid of Tests Constituent characterization Differential Scanning Calorimetry (DSC) Effect of degree of curing epoxy resin glass transition temperature spec. dh/dt [W/g] exo not crosslinked resin T g o curing degree 80% curing degree 94% H T H r reaction enthalpy endo curing degree100% T g temperature [ C] 8

9 The Pyramid of Tests Constituent characterization Dynamic Mechanical Analysis (DMA) Effect of moisture on glass transition K/min - dry 1 K/min - wet E'-modulus [MPa] DMA (3-point-bending) test frequency: 1 Hz heating rate: 2 K/min epoxy temperature [ C] 9

10 The Pyramid of Tests Constituent characterization Thermomechanical Analysis (TMA) Thermal expansion of fiber composites 35 dimensional change l, µm Short fiber BMI Coefficient of Thermal Expansion l α = 1 T l o temperature, C 10

11 The Pyramid of Tests Constituent characterization Dielectrical Analysis (DEA) Inline characterization of curing ion viscosity log µ i, Ω cm neat epoxy resin (dry) curing time, min temperature ion viscosity temperature, C glass transition temperature T g, C log µ i T g DSC T g DMA neat epoxy resin (dry) cure temperature: 180 C curing degree α DSC, % ion viscosity log µ i, Ωcm 11

12 Scientific concept and methodology I The Pyramid of Tests High Performance Composites FACC AG, A FACC AG, A full scale tests detail and sub-component test standardized test specimens (laminates) constituent characterization application simulation special laminate tests damage tolerance fatigue etc tensile/compression tests shear tests basic fracture mechanics (DCB, ENF) analytical,spectroscopical methods microscopy mechanical, thermomechanical tests 12

13 The Pyramid of Tests Standardized test specimens Monotonic tests under different loading conditions tension compression bending shear - inplane shear (IPS) - interlaminar shear strength (ILSS) compression after impact (CAI) fracture toughness (G IC, G IIC,..)... 13

14 The Pyramid of Tests Standardized test specimens Interlaminar fracture toughness under mode I loading conditions B: Breite P a Compliance -Methode: G IC = 2 P 2B dc da δ C = = C a n P Bei linear elastischer Balkentheorie ergibt sich für n = 3: P GIC = 3 δ 2Ba 0 P Kraft P P max A 1 A 2 a 1 a 2 Rißinitiierung a 3 A 3 A 4 Rißwachstum a 4 Area -Methode: G IC A i = B a i Weg δ 14

15 Case Study 1 Duromer NanoComposites Fracture toughness vs. modulus for CSR-modified epoxy resins (Soft-Particle Thermoset NanoComposites) fracture toughness K IC, MPa*m 1/2 2,0 1,8 1,6 1,4 1,2 1,0 0,8 0,6 toughness modifiier M10CSR-8 M10CSR-4 M10n M10CSR-2 basic resin M10CSS-1 nano filler conventional filler Soft-Particle Modification Improvement of: Modulus: Factor 1.15 Toughness: Factor dynamic modulus E, MPa source: G. Pilz 15

16 Case Study 1 Duromer NanoComposites Fracture toughness vs. Modulus for CNF-modified Epoxy Resins Hard-Particle Thermoset NanoComposites fracture toughness K IC, MPa*m 1/2 4,0 3,5 3,0 2,5 2,0 1,5 1,0 EP EP_CNF-4 Effect of nano filler EP_CNF-1 EP_CNF-2 Hard-Particle Modification Improvement of: Modulus: Factor 1.5 Toughness: Factor 4.3 0, dynamic modulus E, MPa source: G. Pilz 16

17 The Pyramid of Tests Standardized test specimens Compression after Impact (CAI) Falling weight tower for introducing impact damage 17

18 The Pyramid of Tests Standardized test specimens Compression after Impact (CAI) Effect of impact energy on compression strength compression strength, MPa mm/min 23 C impact energy, J 18

19 The Pyramid of Tests Standardized test specimens Fatigue tests under different loading conditions Stress based approach P cyclic load P max log σ a P min R = P min /P max t? fatigue stress limit P(t) σ(t) log N f stress, σ cycles σ σ max E S E dyn relative modulus damage accumulation cyclic creep E dyn E S strain, ε σ min ε min ε max ε log (N) 19

20 Case Study 2 Fatigue Stress based approach Hysteretic heating in woven carbon fabric RTM laminates IR-Camera Orion - Cedip Infrared Systems 1) N= Local delamination (thermal flashes) 2) N= Localized edge heat sources ) N= Localized heat sources grow to global heat source 4) N= Failure Tensile fatigue test: 75 % of tensile strength R=0.1, 10 Hz, 23 C 20

21 Case Study 3 Fatigue Stress based approach Artificial defects in woven carbon fabric RTM laminates Laminate with foil defects ( mm) Specimen with notch (diameter: 6.35 mm) Two layers of teflon foil sealed with an adhesive tape in order to entrap air 21

22 Case Study 3 Fatigue Stress based approach Effect of artificial defects on S/N curves of woven carbon fabric RTM laminates σ, MPa CF-EP qi CF-EP qi-foil defect CF-EP qi-notch C, 10 Hz, R= N, 1 22

23 Case Study 3 Fatigue Stress based approach Effect of stress level on dynamic and secant modulus of woven carbon fabric RTM laminates 1,1 1,0 E dyn,rel, E s,rel, 1 0,9 0,8 0,7 0,6 INJ W-QI Edyn_35% Es_35% Edyn_60% Es_60% Edyn_70% Es_70% Edyn_75% Es_75% 0, N, 1 23

24 The Pyramid of Tests Standardized test specimens Fatigue tests under different loading conditions Fracture mechanics approach DCB-specimen P cyclic load a 0 P max P P log da/dn brittle composite 1 n toughened composite P min R = P min /P max t log G Imax ( G) 24

25 Case Study 4 Fatigue Fracture mechanics approach Fatigue delamination growth in polymer matrix composites Effect of polymer matrix da/dn, mm/cycle 10-2 CF-EP1 CF-EP1 CF-PEEK 10-3 CF-PEEK CF-EP2 CF-EP C, 5 Hz G Imax(MCC), J/m2 25

26 Scientific concept and methodology I The Pyramid of Tests High Performance Composites FACC AG, A FACC AG, A full scale tests detail and sub-component test standardized test specimens (laminates) constituent characterization application simulation special laminate tests damage tolerance fatigue etc tensile/compression tests shear tests basic fracture mechanics (DCB, ENF) analytical,spectroscopical methods microscopy mechanical, thermomechanical tests 26

27 The Pyramid of Tests Sub-Component tests 27

28 Case Study 5 Delamination in L-shaped composite components displacement controlled loading machine displacement and force measured Aramis video system (correlation method) for measurement of deformation distribution 28

29 Case Study 5 Delamination in L-shaped composite components Comparison of experiment and simulation 29

30 Case Study 5 Delamination in L-shaped composite components Comparison of deformation distribution max. principal strains 30

31 Case Study 6 Sub-Component test Certification test for A330/A340 program Subcomponent test specimen Fmax [N] Fmin [N] s max [mm] s min [mm] 0,4 0,3 force, N , , , displacement, mm Test set-up cycles Cyclic testprogram -0,2 31

32 Case Study 6 Subcomponent test Lock-in thermography for defect detection Photothermography testing stand (transmission mode) Lamps Specimens IR-Camera Power Supply Testing Stand - Photothermal Stimulation 1250 W Halogen Lamps - Sine and pulse stimulation - Reflection and transmission mode Testing parameters - Pulse (Pulse length 1-2 s) - Sine (f = 0.01 to 0.5 Hz) Data reduction - Altair Lock-In and Matlab Temperature vs. Time Amlitude and phase of the temperature response (Lock-In) 32

33 Case Study 6 Subcomponent tests Lock-in thermography Defect detection in a carbon fabric RTM subcomponent Defects recognized by temperature phase difference 33

34 Scientific concept and methodology I The Pyramid of Tests High Performance Composites FACC AG, A FACC AG, A full scale tests detail and sub-component test standardized test specimens (laminates) constituent characterization application simulation special laminate tests damage tolerance fatigue etc tensile/compression tests shear tests basic fracture mechanics (DCB, ENF) analytical,spectroscopical methods microscopy mechanical, thermomechanical tests 34

35 The Pyramid of Tests Full scale tests 35

36 Scientific concept and methodology II Material properties, material models/laws Design geometry model material (pre)selection Input data Component simulation phenomenological models micro-structure based models feed-back loop Component testing load deformation and strain component temperature failure Tailored and Safe Components 36

37 Acknowledgement Part of the research work of this presentation was performed at the Polymer Competence Center Leoben GmbH (PCCL, Austria) within the framework of the K plus -program of the Austrian Ministry of Traffic, Innovation and Technology. The PCCL is funded by the Austrian Government and the State Governments of Styria and Upper Austria. 37