Comprehensive study on the time-dependent inelastic deformation of carbon composites at elevated temperatures

Transcription

1 Comprehensive study on the time-dependent inelastic deformation of carbon composites at elevated temperatures 5TH ANNIVERSARY OF THE INSTITUTE FOR CARBON COMPOSITES Garching, A. Chripunow

2 Content 1. Introduction 2. Test Setup, Procedure and Materials 3. First Results 4. Summary and Outlook Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 2 2

3 Introduction Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 3 3

4 Introduction Calomfirescu, Maier, Stolz, Körwien Experience and Future Requirements w.r.t. damages in composite structures from the Cassidian perspective, AVT 211 WS on Understanding Failure Mechanisms of Composites, Riga 2013 Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 4 4

5 Introduction Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 5 5

6 Content 1. Introduction 2. Test Setup, Procedure and Materials 3. First Results 4. Summary and Outlook Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 6 6

7 Test Setup Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 7 7

8 Test Setup 8 testing positions Programmable electromechanical actuators Loading Range: -5kN till 20kN 2 optical measuring sytems Temperature Range: -50 C till 350 C Maximum rel. Humidity of 80 C Almost inert atmosphere (N 2 ) with remaining O 2 -concentration of 0,5% 1% Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 8 8

9 Procedure- Experimental Creep/Recovery tests Loading time: 1h Unloading time: 8h T=25 C-250 C 10%- 50% T test 2-5 specimen Comparison of fabric and UD Tests under air and N 2 -atmosphere (T=150 C, 200 C, 250 C) L 0 =60mm Clamping length: 130mm Specimen Dimensions: 220mm x 25mm x 2,3mm Cyclic tests Loading time: 5 min Unloading time: 40 min 12 cycles Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 9 9

10 Procedure- Modelling Determination of Evolution of VP during loading: VP ( t, T, ) C( T ) N ( T ) t n(, T ) [Zapas LJ, Crissman JM: Creep and recovery behaviour of ultra-high molecular weight polyethylene in the region of small uniaxial deformations, Polymer, 1, 1984, 25(1), pp ] Charactrization of Evolution of VE during loading: VE dg2 ( t,, T) g0 ( ) D0 g1( ) D d d [Lou YC, Schapery RA: Viscoelastic Characterization of a Nonlinear Fiber-Reinforced Plastic, Journal of Composite Materials, 5, 1971, pp ] t 0 Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 10 10

11 Procedure- Additional Analysis Thermal: Account for evolution of properties affected by elevated temperatures DSC: state of cure DMA: development of Tg TGA: mass loss FTIR: degradation of thermoset constituent of matrix due to oxidation Damage: Investigation of crack development after Creep/ Recovery tests by µct Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 11 11

12 Materials Carbon/epoxy prepreg Used in state-of-the-art aircrafts Hexcel M18-1/G947: Plain weave (97/3, carbon/glass) => UD Hexcel M18-1/G939: Satin weave (50/50, carbon/carbon) => fabric Matrix: amorph polymers- 84% epoxy resin + 16% high temperature resistant thermoplastic component (PEI) T g 210 C 230 C T max(in-service) =135 C Layups: [[45/-45] 3 ] s (UD), [[(45,-45)/(-45/45)] 2 ] s (fabric), [0/45/-45/90] s Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 12 12

13 Content 1. Introduction 2. Test Setup, Procedure and Materials 3. First Tests and Results 4. Summary and Outlook Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 13 13

14 Longitudinal Strain [%] First 0,9 Results- Comparison UD vs. G939 Fabric 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 Fabric: -7% Fabric: -0,5% Fabric: -5,8% Fabric: -11% 25 C G947 Fabric: 10% UTS Fabric: 20% UTS Fabric: 30% UTS Fabric: 40% UTS UD: 10% UTS UD: 20% UTS UD: 30% UTS UD: 40% UTS 0,0 no difference Time [h] Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 14 14

15 0,60 0,55 Fabric: -2% 100 C G939 G947 Fabric: 10% UTS Fabric: 30% UTS UD: 10% UTS UD: 30% UTS 0,50 Longitudinal Strain [%] 0,45 0,40 0,35 0,30 0,25 0,20 0,15 0,10 0,05 0,00 Fabric: -7% Fabric: +50% Time [h] Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 15 15

16 3,5 3,0 Fabric: -20% 150 C G939 G947 Fabric: 10% UTS Fabric: 30% UTS Fabric: 50% UTS UD: 10% UTS UD: 30% UTS UD: 50% UTS Longitudinal Strain [%] 2,5 2,0 1,5 1,0 Fabric: -10% Fabric: -33% 0,5 0,0 Fabric: -1% Fabric: -21% Time [h] Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 16 16

17 C G939 G947 Fabric: 10% UTS Fabric: 30% UTS Fabric: 50% UTS UD: 10% UTS UD: 30% UTS UD: 50% UTS Longitudinal Strain [%] Fabric: -27% Fabric: -12% Fabric: -52% Fabric: -50% Fabric: +22% Fabric: -21% Time [h] Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 17 17

18 Fabric 200 C 50% D 00 C 0% Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 18 18

19 Strain after 8h of Recovery First Results- Cyclic loading tcr=5min Remaining Longitudinal Deformation [%] 0,20 0,18 0,16 0,14 0,12 0,10 0,08 0,06 0,04 0,02 0,00 tcr=10min tcr=20min Strain after 1st CR-cycle VP 100 C, 40% UTS ( t, T, ) 0, Time [min] C( T ) N ( T ) Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics Longitudinal Strain [%] 1,2 1,0 0,8 0,6 0,2 t n(, T ) 0, Time [h] tcr=5min

20 Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 20 20

21 Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 21 21

22 Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 22 22

23 First 3,5Results- Comparison Air vs. N 2 Longitudinal Strain [%] 3,0 2,5 2,0 1,5 1,0 N2: -3% N2: -1,5% 150 C N2: -5,5% Air: 10% UTS Air: 30% UTS Air: 50% UTS N 2 : 10% UTS N 2 : 30% UTS N 2 : 60% UTS 0,5 0,0 N2: -5,5% N2: +3% Time [h] Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 23 23

24 8 200 C 7 N2: +11% Air: 10% UTS Air: 30% UTS Air: 50% UTS N 2 : 10% UTS Longitudinal Strain [%] N2: -1% N2: -2% N2: +10% N 2 : 30% UTS N 2 : 50% UTS 1 0 N2: +24% N2: +38% Time [h] Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 24 24

25 Longitudinal Strain [%] 1,5 1,4 1,3 1,2 1,1 1,0 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0,0 N2: +5,7% N2: +3,7% N2: +5,5% 250 C N2: +17% Time [h] Air: 10% UTS Air: 20% UTS Air: 30% UTS N 2 : 10% UTS N 2 : 20% UTS N 2 : 30% UTS no difference Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 25 25

26 Irreversible Heatflow [J/g] Differential Scanning Calorimetry C, air 200 C, N Testing Time [min] Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 26 26

27 Content 1. Introduction 2. Test Setup, Procedure and Materials 3. First Tests and Results 4. Summary and Outlook Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 27 27

28 Summary and Outlook procedure to investigate time-dependent in-plane shear response of CFRP depending on temperature, load level, fibre reinforcement and presence of oxygen At T 150 C the fabric shows significant lower strain values during the creep/recovery test than the UD Higher crack density for UD at 200 C Tests under inert atmosphere at T=150 C lead to slightly lower strain values whereas at T>150 C the strain values increase, probably due to slowdown of post-cure Consideration of viscoplasticity Cyclic tests not feasible At 200 C post-curing effects affecting VP-response repeat tests to verify trends apply presented procedure on quasi-isotropic layups apply models in order to determine VE and VP parameters as functions of temperature and load level detailed investigation on cracks and post-curing effects Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 28 28

29 Contact: Dipl.-Ing. André Chripunow Department 210: Mechanical Technology, Simulation Homepage: Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 29 29

30 Introduction of WIWeB is the center of competence of the Bundeswehr for technology, safety and reliability of materials, fuels and lubricants. Munich Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 30 30

31 Introduction of WIWeB Tasks and services and consulting services of WIWeB Materials Structures Tribology Fuels, Lubricants Chemistry, Product Safety, Environmental Protection Surface Technology, Material Protection, Equipment Integrated, interdisciplinary service and advice on the entire life cycle of products and equipment Development Research Testing Admission / Qualification Procurement Terms of Reference Quality assurance Use Application / Education Materials Protection Damage early detection Damage Investigation Disposition / Exploitation Chemical analysis Assessment and identification of options Determination of Temperature-Dependent Mechanical temperatures Properties of Carbon Fibre Reinforced Plastics 31 31