STELIA AEROSPACE NORTH AMERICA

Transcription

1 STELIA AEROSPACE NORTH AMERICA SPACE QUALIFIABLE BONDED JOINTS BETWEEN CARBON FIBER REINFORCED POLYMER (CFRP) AND ALUMINUM SOHEILA MAHDAVI

2 Outline 1 2 Stelia Presentation Carbon Fiber Reinforced Polymer Composites (CFRP) 3 Objective 4 Requirements specification 5 Qualification Tests 6 Manufacturing and testing of Prototypes 7 Conclusion 2

3 STELIA Worldwide N 1 in Europe for aerostructure N 3 worldwide for aerostructure N 3 worldwide for first and business class seats > 6,400 employees $ 2,5 billion revenue $ 210 million R&D N 1 worldwide crew seats STELIA Group, an aerospace multi-specialist 3

4 STELIA Group, a global presence Manufacturing Commercial desk 6,400 employees 4,600 in France with 3 main production sites & 600 in engineering 1,000 in North Africa 600 in North America 5 fully owned Airbus subsidiaries 4

5 STELIA North America Lunenburg Facility Composite Manufacturing Mirabel Facility- Assembly and Systems installation Mirabel Facility Composite Manufacturing 5

6 BOMBARDIER Global 7000 / 8000 Design and build Plug & Fly (includes systems) Supply chain management optimization 6

7 The Competitive Challenge The Space and Aerospace Industry are directed more heavily than in the recent past towards: > new materials; > lower prices; > faster manufacturing cycles > production innovation The challenge for Stelia to grow its market share is to develop innovative manufacturing techniques that are consistent with existing and future customer demands. The challenge is not only from a technology standpoint but also from a financial standpoint in: > people, > Time > willingness to invest in R&D. 7

8 Carbon Fiber Reinforced Polymer Composites (CFRP) Advantages: High strength Light weight Dimensional stability under large temperature variations Challenges: rarely form the totality of the structure and still need to be assembled with metallic parts: > Titanium thermally stable under a large range of temperature expensive more complex to manufacture > Aluminum commonly used metallic parts for space applications CTE completely differs from CFRP s» dimensional issues under the influence of a varying temperature 8

9 Project Objective Select adhesives and associated bonding processes To bond Carbon Fiber Reinforced Polymer (CFRP) and aluminum For the Canadian Space Agency (CSA) 9

10 Requirements specification Phase I: Literature review Selection, identification and analysis of adhesives > <1.0% TML (Total Mass Loss) > <0.1% CVCM (Collected Volatile condensable Material) > < 10% bonding strength and stiffness variation at -170 C < T <160 C Design and fabrication of test coupons for characterization of the adhesives and bonding processes Test the coupons to measure and characterize the bonding strength and stiffness over the specified temperature range. 10

11 Requirements specification Phase II: Bonded joint prototype development and qualification Design three CFRP-aluminum on a > CFRP plate > CFRP strut > CFRP tube Development of bonding procedure Procurement/manufacturing of the prototypes Thermal-vacuum (T-Vac) testing of each prototype and verify its bonding Random vibration testing to test the bonds 11

12 Qualification tests on coupons Flatwise tensile test (ASTM D7291) Thick laminate (0.46 ) tested at room temperature ambient (RTA) > failure mode within ply Lap-shear adhesion (ASTM D5868) aluminum bonded to CFRP with adhesives tested at: > room temperature ambient (RTA), > cold temperature dry (CTD) : -70 C, > elevated temperature dry (ETD) : +160 C. Adhesive selection based on qualification test results: film adhesive 1 film adhesive 2 film adhesive 3 film adhesive 4 12

13 Manufacturing of the prototypes Prototype 1: aluminum part bonded on a flat CFRP plate Prototype 1 (consisting of 16 plies cured in OA ) Use G10 sheets to avoid bagging under the mass and around the standoff during curing in the autoclave Standoffs after curing Broken standoff 13

14 Manufacturing of the prototypes Prototype 2: aluminum end fitting on a CFRP strut The layup mold on a turning fixture 8 plies of CFRP on the adhesive and the mold Final Part 14

15 Manufacturing of the prototypes Prototype 3: aluminum end-fitting on a CFRP tube A mold is required for manufacturing a tube out of composites The mold-fixture with the endfitting, Two layers of adhesive 3 on the end fitting, Sixteen layers of CFRP on the adhesive and the mold. Final Part 15

16 Prototypes testing T-Vac testing Vacuum test at Tor Thermal cycling > Number of cycles: 10 cycles > Temperature range -160 C to +140 C > Tolerances: Cold: -10 C, +0 C / Hot: -0 C, +5 C > Minimum time at plateau: 30 minutes > Maximum rate of change: 10 C/min. Three prototypes are placed on a solid aluminum plate inside the chamber. 16

17 Inspection after TVAC test After TVAC, a visual inspection of three prototypes is performed. There is no apparent damage in the CFRP or the bondline for prototype 1. Prototype 1 passed the test. One standoff seems to be weakened due to stress concentration. 17

18 Inspection after TVAC test (Cont.) For prototype 2: there was no apparent damage in the CFRP or the bondline. Prototype 2 passed the test. 18

19 Inspection after TVAC test (Cont.) For prototype 3: there was no apparent damage in the CFRP or the bondline from the outside. Debonding observed from the insdie. Prototype 3 failed the test. 19

20 Random vibration Tests were performed at DFL: 40,000 lbf capacity shaker 150 GRMS acceleration limit 37,000 lb force limit Mass of slip table is lb Test plan: 20

21 Random vibration Prototype 1: Two stand-offs broke during adhesive cure Prototype 2 Prototype 3 21

22 Random vibration Prototype 3 Evidence of failure in adhesive 22

23 Random vibration Results summary 23

24 Conclusion Three prototypes were design and manufactured. Co-curing endfitting with adhesive 3 and prepreg was successful. Prototypes 1 and 2 passed the TVAC test. Prototype 3 failed the TVAC test. Random vibration test for prototype 1 is not conclusive: Standoff failed before reaching 50% load level. Prototype 2 passed random vibration test. Random vibration for prototype 3 is not conclusive. There was initial failure in the bondline after TVAC. Adhesive 3 can be used for bonding aluminum to CFRP for space application: The successful application will depend on the bondline size. There is a critical bondline size/surface area above which thermal stresses cause failure in the bondline. 24

25 Thank You 25

26 Preselection of adhesives pre-selected film adhesives to be tested during Phase I: film adhesive 1 film adhesive 2 film adhesive 3 film adhesive 4 The CFRP laminates: quasi-isotropic layup Plain weave fabric Resin: Toughened epoxy 26

27 Flatwise tensile strength Flatwise tensile strength per ASTM D7291. Coupon dimensions: D=1 thickness 0.1. Flatwise tensile results: Three coupons: 4257 psi, 4287 psi, and 4651 psi. CSA PT9 - CAL MAR-17 27

28 Assessment of results Materials set validation: FW tensile strength: min of 4257 psi > 2500 psi -> Pass. Lap-shear strength: min of psi > 2000 psi -> Pass. Inspection of CFRP aluminum joint prototypes: Prototype 1: Pass (Not conclusive). Prototype 2: Pass. Prototype 3: Fail. CSA PT9 - CAL MAR-17 28

29 Random vibration Prototype 1 Two stand-offs broke during adhesive cure 29

30 Random vibration Prototype 2 Vibration test setup 30

31 Random vibration Prototype 2 Vibration test setup 31

32 Random vibration Prototype 3 Vibration test setup 32

33 Random vibration Prototype 3 Vibration test setup 33

34 Mirabel Facility + 35,000 sqft Design, analysis and R&D in advance composite structures Long term partnership with NRC. NRC co-located with Stelia in Mirabel Automated Fiber Placement Manufacturing Space structures Clean Room 8,000 sqft, Class 100,000 Autoclave 6 feet diameter x 20 feet long Reticulation Machine 56x96 34