CFRP-AM FOR INDIVIDUALIZED, COST-EFFICIENT AND SUSTAINABLE ULTRA-LIGHTWEIGHT PARTS

Transcription

1 CFRP-AM FOR INDIVIDUALIZED, COST-EFFICIENT AND SUSTAINABLE ULTRA-LIGHTWEIGHT PARTS Paolo Ermanni ETH Zurich, Laboratory of Composite Materials and Adaptive Structures 14. Wissenschaftstag: Additive Composite Structures Anwendung generativer Fertigungsverfahren im Faserverbundleichtbau DLR Braunschweig, Institut für Faserverbundleichtbau 19 October 2017 Paolo Ermanni DLR Braunschweig 19 October

2 Research areas at CMASLab Materials systems & processes Multi-functional lightweight structures We apply our competences in a wide range of fundamental and more applied projects, being particular interested in problems concerning advanced manufacturing processes, tunable material properties, conformal morphing and smart handling of vibrations. Modeling and simulation Electro-Mechanical Systems Paolo Ermanni DLR Braunschweig 19 October

3 Lightweight Design: Fiber Reinforced Polymers CFRPs are excellent lightweight materials Excellent potential for material orientation according to the load paths Good possibilities for an efficient material arrangement (depending on manufacturing process) Good possibilities for integration of functions: K complex geometries J functional layers material orientation lightweight materials material arrangement integration of functions Paolo Ermanni DLR Braunschweig 19 October

4 Lightweight Design:Additive Manufacturing Moderate (polymers) to good (metals) lightweight materials Limited possibilities for material orientation according to the load paths Excellent possibilities for an efficient material arrangement Good possibilities for integration of functions: J complex geometries K functional layers material orientation lightweight materials material arrangement integration of functions Paolo Ermanni DLR Braunschweig 19 October

5 Lightweight Design: CFRP & AM à Combination of strengths With local CFRP reinforcement excellent lightweight materials Excellent possibilities for material orientation according to the load paths Excellent possibilities for an efficient material arrangement Excellent possibilities for integration of functions: J complex geometries J functional layers material orientation combination lightweight materials material arrangement integration of functions Paolo Ermanni DLR Braunschweig 19 October

6 Main research areas Materials systems & processes FSI in Processing of highly Integrated CFRP Structures CFRP & Additive Manufacturing 3D AM of fibre reinforced thermoplastics (CLF) Bicomponent Fibers for Thermoplastic Composites Melt furnace and spinneret Sizing application Thermoplastic matrix application (proposed coating process) Gathering shoe Take-up Paolo Ermanni DLR Braunschweig 19 October

7 Introduction Showcase Pilatus PC6 Instrument Panel Ralh Kussmaul Daniel Türk PDZ, ETH Zurich Paolo Ermanni DLR Braunschweig 19 October

8 Reference: Aluminum Design Rivet nut DZUS fastener DZUS fastener Support strap Base plate No. Of parts: 118 Weight: 1480 g Rivet nut Paolo Ermanni DLR Braunschweig 19 October

9 Concept: Sandwich structure with CFRP facings and AM core AM core made by SLS (polymer): - SLS of honeycombs - innovative honeycombdesign AM load introduction elements made by SLM (metals): - load-oriented - tailored performance CFRP autoclave prepregfacings: - excellentlightweight materials - robust & well establishedprocess Integration of functions: - integrated positioningelements - integrated tooling Paolo Ermanni DLR Braunschweig 19 October

10 Design Features: Tailored mechanical performance Printed honeycomb CFRP skin Solid core for high loaded areas & honeycomb core with variable density for lower loaded areas Variable stiffness design according to local loads determined by a novel gradient-based optimizer. (0/90) (0/90/45/-45/90) (0/90/45/-45) Paolo Ermanni DLR Braunschweig 19 October

11 Design Features: Integrated positioning elements pocket with insert plug & play snap-in mount quick positioning tooling for support strap prepreg positioning Paolo Ermanni DLR Braunschweig 19 October

12 Design Features: Integrated manufacturing aids integrated spacers for holes to be machined integrated honeycomb closure integrated panel edge protection (to be machined) Paolo Ermanni DLR Braunschweig 19 October

13 Manufacturing Concept simple tooling lay-up plug & play autoclave curing postprocessing complex additive elements vacuum valve vacuum bag bleeder fabric metal support sealant tape tooling base plate CFRP prepreg Paolo Ermanni DLR Braunschweig 19 October

14 First Facing & Core Assembled Paolo Ermanni DLR Braunschweig 19 October

15 Second Facing Assembled Paolo Ermanni DLR Braunschweig 19 October

16 Final Demonstrator Paolo Ermanni DLR Braunschweig 19 October

17 Results mass [g] weight reduced by 40 % honeycomb (Nomex) load introduction & joining elements CFRP facings AM cores metal base structure alu reference panel CFRP & AM sandwich panel Paolo Ermanni DLR Braunschweig 19 October

18 Results mass [g] number of parts reduced by 50% SLM inserts CFRP facings honeycomb (Nomex) AM cores rivet nuts & DZUS fasteners rivets metal base structure alu reference panel CFRP & AM sandwich panel Paolo Ermanni DLR Braunschweig 19 October

19 Conclusion CFRP & Additive Manufacturing Novel lightweight integral designs with high structural complexity Significant reduction of number of parts compared to reference design Manufacturing of complex structures with simple tooling e.g. by the well established and robust autoclave process structural complexity differential design combined CFRP & AM integral design degree of integration Paolo Ermanni DLR Braunschweig 19 October

20 Main research areas Materials systems & processes FSI in Processing of highly Integrated CFRP Structures CFRP & Additive Manufacturing 3D AM of fibre reinforced thermoplastics (CLF) Bicomponent Fibers for Thermoplastic Composites Melt furnace and spinneret Sizing application Thermoplastic matrix application (proposed coating process) Gathering shoe Take-up Paolo Ermanni DLR Braunschweig 19 October

21 Why AM of Fiber Composites? Costs Performance Flexibility Material efficiency 3D printing Low cost Limited strength (plastics) High weight (metal) No changeover time In-Situ: Minimal logistics cost No waste 3D carbon printing Low costs (no moldings, cheap raw material) High strength Lightweight No changeover time In-Situ: Minimal logistics cost No waste Carbon fiber High moldings costs High strength High changeover time High waste Raw material Lightweight Paolo Ermanni DLR Braunschweig 19 October

22 Pultrusion-Extrusion Process (CLF) Yarns Pultrusion Q Q thermoplastic reinforcement fiber Martin Eichenhofer Extrusion Rod *patented technology, pictures can not be published without approval from Martin Eichenhofer Paolo Ermanni DLR Braunschweig 19 October

23 Pultrusion-Extrusion Prozess (CLF) Yarns Pultrusion Q Q Extrusion > fibers Rod *patented technology, pictures can not be published without approval from Martin Eichenhofer Paolo Ermanni DLR Braunschweig 19 October

24 Application Principles Process Head T,V Process Head T,V Extrusion + Compaction Extrusion Composite Layup Composite Layup Free Form Printing 3D Printing / AFP Tape Laying (3D+) (3D) (2D) Paolo Ermanni DLR Braunschweig 19 October

25 State of the Art CLF Robotic Print Systems CF/PA12 Robotic Printer CF/PEEK Robotic Printer Paolo Ermanni DLR Braunschweig 19 October

26 CLF Robotic Print Systems Paolo Ermanni DLR Braunschweig 19 October

27 Example: Locally Reinforced Structures (single strand) Qualitative Assessment Commonly used CF/PEEK sheet CF/PEEK sheet locally reinforced with CLF system Paolo Ermanni DLR Braunschweig 19 October

28 Example: Locally Reinforced Structures (multiple strands) CF/PEEK stringer-stiffened panel multi-layer stacking of individual fiber composite strands Paolo Ermanni DLR Braunschweig 19 October

29 Example: Ultra-Lightweight Structures (<10mg/cm 3 ) Open Lattice Sandwich Panel CF/PA12 sandwich panel CF/PEEK sandwich panel Paolo Ermanni DLR Braunschweig 19 October

30 Example: Ultra-Lightweight Structures (<10mg/cm 3 ) Out-of-Plane Compression Tests [A] CLF Specimen, ETH Zurich [B] Cuboct lattice, MIT [C] Pyramidal fiber composite lattice, Harbin / Northeastern University [D] Tetrahedral fiber composite lattice, Harbin Institute of Technology [E] Pyramidal fiber composite lattice, Harbin Institute of Technology Paolo Ermanni DLR Braunschweig 19 October

31 Example: Ultra-Lightweight Structures Close Up 3-Point Bending Tests printed stringer reinforcement o 100% thermoplastic composite o AM stringer reinforcements o Ultra-lightweight core app. 5 mg/cm 3 no adhesive bond Paolo Ermanni DLR Braunschweig 19 October

32 New Focus Project: Carbon Factory Development of a production system combining conventional FDM 3D-printing with 3D-printing of continuously reinforced composites to realize highly integrated, selectively reinforced structures Conventional 3D-Printing Composite 3D-Printing (CLF) Paolo Ermanni DLR Braunschweig 19 October

33 Carbon Factory: Use Case 1.) 3D Print Plastic F 2.) 3D Print Carbon F/2 Carbon Plastic F/2 3.) 3D Print Plastic Paolo Ermanni DLR Braunschweig 19 October

34 Main research areas Materials systems & processes FSI in Processing of highly Integrated CFRP Structures CFRP & Additive Manufacturing 3D AM of fibre reinforced thermoplastics (CLF) Bicomponent Fibers for Thermoplastic Composites Melt furnace and spinneret Sizing application Thermoplastic matrix application (proposed coating process) Gathering shoe Take-up Paolo Ermanni DLR Braunschweig 19 October

35 Rapid Stamp Forming of Thermoplastic Composites State-of-the-art in high volume composite production. Use of hybrid intermediate materials. Dr. Joanna Wong Christoph Schneeberger Parallelization: Heating outside of press. Forming and consolidation in mould. Intermediate material Paolo Ermanni DLR Braunschweig 19 October

36 Rapid Stamp Forming of Thermoplastic Composites State-of-the-art in high volume composite production. Use of hybrid intermediate materials. Parallelization: Heating outside of press. Forming and consolidation in mould. Intermediate material Heating Paolo Ermanni DLR Braunschweig 19 October

37 Rapid Stamp Forming of Thermoplastic Composites State-of-the-art in high volume composite production. Use of hybrid intermediate materials. Parallelization: Heating outside of press. Forming and consolidation in mould. Intermediate material Heating Forming Paolo Ermanni DLR Braunschweig 19 October

38 Rapid Stamp Forming of Thermoplastic Composites State-of-the-art in high volume composite production. Use of hybrid intermediate materials. Parallelization: Heating outside of press. Forming and consolidation in mould. Intermediate material Heating Forming Consolidation and solidification Paolo Ermanni DLR Braunschweig 19 October

39 Rapid Stamp Forming of Thermoplastic Composites State-of-the-art in high volume composite production. Use of hybrid intermediate materials. Parallelization: Heating outside of press. Forming and consolidation in mould. Intermediate material Composite part Heating Forming Consolidation and solidification Demolding Paolo Ermanni DLR Braunschweig 19 October

40 State-of-the-Art Intermediate Materials C. Schneeberger, J.C.H. Wong, and P. Ermanni. Hybrid Bicomponent Fibres for Thermoplastic Composite Preforms. Manuscript submitted. Paolo Ermanni DLR Braunschweig 19 October

41 Bicomponent Fibers Reinforcing fibers individually clad in a thermoplastic polymer sheath. Advantages of this concept Full wet-out for fast consolidation à low cycle time Minimized flow lengths Sintering rather than impregnation High drapeability à complex geometries Can also be used in Alternative Processing Routes Automated tape laying, filament winding Braiding, knitting, stitching Additive manufacturing Core fiber radius r $ and sheath thickness h. C. Schneeberger, J.C.H. Wong, and P. Ermanni. Hybrid Bicomponent Fibres for Thermoplastic Composite Preforms. Manuscript submitted. Paolo Ermanni DLR Braunschweig 19 October

42 Economical In-line Coating Process Implementation of the coating method in-line with the glass fiber spinning process. One-step process. Enables access to geometrically separate filaments. Paolo Ermanni DLR Braunschweig 19 October

43 Method 1: Dip-Coating in Polymer Solution Preparation of single glass filaments of finite length 0.5 m to 1 m. Fibres drawn through dilute polymer solution. Take-up on winder at constant speed. Winder Fiber Coating bath Paolo Ermanni DLR Braunschweig 19 October

44 Methodology: Dip-Coating in Polymer Solution Preparation of single glass filaments of finite length 0.5 m to 1 m. Fibres drawn through dilute polymer solution. Take-up on winder at constant speed. Steel ring Paolo Ermanni DLR Braunschweig 19 October

45 Methodology: Dip-Coating in Polymer Solution Preparation of single glass filaments of finite length 0.5 m to 1 m. Fibres drawn through dilute polymer solution. Take-up on winder at constant speed. Samples investigated using scanning electron microscopy (SEM). Imaging of cross-sectional and transverse views. Steel ring Paolo Ermanni DLR Braunschweig 19 October

46 Thermoplastic material: poly(ester-amide) Aliphatic segmented block co-polymer. Research material provided by Dow Europe GmbH. Thermoplastic behavior: spontaneous organization into semi-crystalline structure by forming hydrogen bonds. Melt viscosity: 1-5 Pa s, Newtonian fluid. «Isotropic» liquid «Organized» solid Source: R. Koopmans, Dow Europe GmbH Paolo Ermanni DLR Braunschweig 19 October

47 Experimental Results: Dip-Coating in Solution Dip-coating of single filaments at controlled speeds. a1 a2 b1 b2 c1 c2 d1 d2 Dip-coating of single filaments at controlled speeds. Different polymer solutions: a. PEA-Chloroform b. PC-Chloroform c. PS-Tetrahydrofuran d. PMMA-Tetrahydrofuran C. Schneeberger, J.C.H. Wong, P. Ermanni Hybrid Bicomponent Fibres: A New Class of PrepregMaterials for Thermoplastic Composites, Submitted. Paolo Ermanni DLR Braunschweig 19 October

48 Technical Challenge: Realization of In-line Process Question to answer: is dip-coating in-line with glass fibre spinning possible? Analytical models for both processes solved for velocity. à Comparison of processing windows. Framework: E-glass fibers with diameters suitable for application in structural composites. Glass Fibre Spinning in-line Dip- Coating Diameters from 10 µm to 20 µm. Coating fluid: PEA-CHCl 3 solutions with variable concentration (1.8 wt% to 12.3 wt%). Coating thicknesses resulting in fiber volume fractions between 0.5 and 0.7. Paolo Ermanni DLR Braunschweig 19 October

49 Theory: Glass Spinning Glass flows at spinneret/take-up: Spinneret: Hagen-Poiseuille flow. Take-up: momvement of solid glass. Conservation of mass. Hagen-Poiseuille law inserted: Q 9 = Tt v = ρ > v = ρ gh R Q m : volumetric flow rate ρ g : density of glass g: gravitational acceleration h: height of glass melt above spinneret R: flow resistance Typical processing speeds: ~ m/s Reported processing speeds: 8-83 m/s Achievable processing speeds: 1.15 m/s and higher C. Schneeberger, J.C.H. Wong, P. Ermanni Manufacturing of Bicomponent Fibers for Thermoplastic Composites: A Feasibility Study ECCM17 European Conference on Composite Materials, Munich, Germany, th June Paolo Ermanni DLR Braunschweig 19 October

50 Theory: Dip-Coating of Cylinders Coating thickness is a function of viscosity, surface tension, and withdrawal velocity! (Landau-Levich problem) Relation between immediate coating thickness h and v $ : 1 v $ h 1 = ρ ρ M w M White & Tallmadge s model: h r = D 1 D with Ca = ηv γ De Ryck & Quéré s D h r = 1.34Ca 1 We with We = ρv@ r γ Assuming coating from a Newtonian fluid. Paolo Ermanni DLR Braunschweig 19 October

51 Theory: Dip-Coating of Cylinders Tallmadge s model: v = n + 1 DC 9 + G 2Y PVR P γ 1 K RQP R P D, S, Y and G represent dimensionless parameters Dynamic viscosity (power law): η = Kγ PQR ànon-newtonian fluids. C. Schneeberger, J.C.H. Wong, P. Ermanni Manufacturing of Bicomponent Fibers for Thermoplastic Composites: A Feasibility Study ECCM17 European Conference on Composite Materials, Munich, Germany, th June Paolo Ermanni DLR Braunschweig 19 October

52 Results of Theoretical Study Models show discrepancy at high capillary numbers Ca. All models suggest overlap in processing speed w/ achievable window in glass spinning. Lower polymer concentrations cause higher processing speeds, but also higher sensitivity of final fiber volume fraction! à Optimization problem between material throughput, process robustness and material costs (solvent losses). Paolo Ermanni DLR Braunschweig 19 October

53 Method: 2 Kiss-roll Coating in Dilute Polymer Solution Coating thickness dependent on: Process parameters Fiber velocity V Contact length on roll R α + β Roll radius R Peripheral roll velocity U = ωr Angle of contact of roll θ _ Material parameters Core fiber radius r Fluid density ρ Fluid viscosity η Fluid surface tension γ Paolo Ermanni DLR Braunschweig 19 October

54 Kiss-roll Coating Setup Fiber guides Preparation of glass monofilaments: Finite lengths < 3 m. Mean diameter of 12 µm. Sized with 1 wt% 3-aminopropyltriethoxy silane (APTES) Fibers drawn over kiss-roll rotating in bath of dilute polymer solution. Polymer: poly(ester-amide) (PEA) (Dow Europe) Aliphatic segmented block co-polymer with low molecular weight. Kiss-roll Polymer solution bath Fiber Drying length Fiber guide Take-up winder Solvent: trichloromethane (CHCl 3 ) (Sigma-Aldrich) Paolo Ermanni DLR Braunschweig 19 October

55 Kiss-roll Coating Demonstration Paolo Ermanni DLR Braunschweig 19 October

56 SEM High Speed Trials Fiber velocity: V = 14 ms 1 Polymer concentration in solution: w M = 5 wt% Peripheral roll velocity: U = 1.88 ms 1 Roll radius: R = 0.1 m Even higher fiber speeds V for in-line coating to yield v $ 0.5, 0.7. Paolo Ermanni DLR Braunschweig 19 October

57 Objective Identify influence of parameters on: Final fiber volume fraction v $ Sensitivity of final fiber volume fraction to fiber speed v $ vs. V High speed trials for fiber speeds V up to 14 m s 1. Parameter study for: Polymer concentration in coating solution w p Peripheral roll velocity U Roll radius R Design of experiment: Two-level full factorial study Parameter Unit Low level High level w M wt% 8 10 U m s R m Paolo Ermanni DLR Braunschweig 19 October

58 Linear Multivariate Regression Fiber velocity V to yield v $ = 0.7 V = c p +cr w M + U + c D R +c R@ w M U + c RD w M R + U R +c R@D w M U R To obtain v $ = 0.7 at high fiber velocity V : Minimize polymer concentration in coating solution w p Maximize peripheral roll velocity U Maximize roll radius R Exception: at high w M Paolo Ermanni DLR Braunschweig 19 October

59 Acknowledgments We thank our supporters and collaborators: Swiss National Science Foundation (Project _165994). Swiss Competence Center for Energy Research (SCCER) Efficient Technologies and Systems for Mobility. Dow Europe GmbH. Leibnitz Institute of Polymer Research Dresden.

60 ...Thankyou for your attention