cfrp-am for individualized, cost -efficient and sustainable ultra-lightweight … · 2017-10-27 ·...

||

Paolo ErmanniETH Zurich, Laboratory of Composite Materials and Adaptive Structures

14. Wissenschaftstag: Additive Composite Structures –Anwendung generativer Fertigungsverfahren im FaserverbundleichtbauDLR Braunschweig, Institut für Faserverbundleichtbau19 October 2017

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

19 October 2017Paolo Ermanni DLR Braunschweig 1

||

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.


Research areas at CMASLab

Multi-functional lightweight structures

Electro-Mechanical Systems

Materials systems & processes

Modeling and simulation

||

Lightweight Design: Fiber Reinforced Polymers

§ CFRPs are excellent lightweight materials

§ Excellent potential for material orientationaccording to the load paths

§ Good possibilities for an efficient material arrangement (depending on manufacturing process)

§ Good possibilities for integration of functions:K complex geometriesJ functional layers lightweight

materialsintegration

of functions

material orientation

material arrangement


||

Lightweight Design:Additive Manufacturing

§ Moderate (polymers) to good (metals) lightweight materials

§ Limited possibilities for material orientationaccording to the load paths

§ Excellent possibilities for an efficient material arrangement

§ Good possibilities for integration of functions:J complex geometriesK functional layers lightweight

materialsintegration

of functions




||

Lightweight Design: CFRP & AM à Combination of strengths

§ With local CFRP reinforcement excellentlightweight 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 geometriesJ functional layers

lightweightmaterials

integration of functions



com

bina

tion


||

Main research areas


3D AM of fibre reinforced thermoplastics (CLF)

CFRP & Additive Manufacturing

FSI in Processing of highly Integrated CFRP Structures

Bicomponent Fibers for Thermoplastic Composites


Take-up

Gathering shoe

Sizing applicationThermoplastic matrix application(proposed coating process)

Melt furnaceand spinneret

||

Introduction Showcase

§ Pilatus PC6Instrument Panel

Daniel TürkPDZ, ETH Zurich

Ralh Kussmaul


||

Reference: Aluminum Design

§ No. Of parts: 118§ Weight: 1480 g

Rivet nut

DZUS fastener

DZUS fastener

Rivet nut

Support strap

Base plate


||

Concept: Sandwich structure with CFRP facings and AM core


§ AM core made by SLS (polymer):- SLS of honeycombs- innovative honeycombdesign

§ AM load introductionelements made by SLM (metals):- load-oriented- tailored performance

§ CFRP autoclave prepreg facings:- excellent lightweight materials- robust & well establishedprocess

§ Integration of functions:- integrated positioningelements- integrated tooling

||

Printed honeycomb

§ Solid core for high loaded areas & honey-comb core with variable density for lower loaded areas

CFRP skin

§ Variable stiffness design according to local loads determined by a novel gradient-based optimizer.

19 October 2017

Paolo Ermanni DLR Braunschweig

10

Design Features: Tailored mechanical performance

(0/90/45/-45)

(0/90)

(0/90/45/-45/90)

|| 19 October 2017Paolo Ermanni DLR Braunschweig 11

Design Features: Integrated positioning elements

tooling for support strap→ prepreg

positioning

snap-in mount→ quick positioning

pocket with insert→ plug & play

|| 19 October 2017Paolo Ermanni DLR Braunschweig 12

Design Features: Integrated manufacturing aidsintegrated spacers for holes to be machined

integrated panel edge protection (to be machined)

integrated honeycomb closure

||

Manufacturing Concept

lay-up→ plug & play

simpletooling

autoclave curing

post-processing

tooling base plate

metal support

complex additive elements

CFRP prepreg

sealant tape

vacuum valve

vacuum bag

bleeder fabric


||

First Facing & Core Assembled


||

Second Facing Assembled


||

Final Demonstrator


||

Results

alu reference panel

mas

s [g

]

CFRP & AM sandwich panel

honeycomb (Nomex)

load introduction & joining elements

CFRP facings

AM cores

metal base structure

weight reduced by 40 %


||

Results

number of partsreduced by 50%

alu reference panel

mas

s [g

]

CFRP & AM sandwich panel

SLM insertsCFRP facingshoneycomb (Nomex)AM coresrivet nuts & DZUS fastenersrivetsmetal base structure


||

§ 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


Conclusion CFRP & Additive Manufacturing

degree of integrationst

ruct

ural

com

plex

ity

combinedCFRP & AM

differentialdesign

integraldesign

||

Main research areas







Take-up

Gathering shoe



||

Why AM of Fiber Composites?

3D carbon printing

Carbon fiber

3D printing

Performance FlexibilityCosts Material efficiency

Low costs (no moldings, cheap raw material)

No wasteNo changeover time

High strength

In-Situ: Minimal logistics cost

Lightweight

Low cost Limited strength (plastics)

No wasteNo changeover time

In-Situ: Minimal logistics costHigh weight (metal)

High wasteHigh changeover time

High moldings costs High strength

LightweightRaw material


||

Q̇

Q̇

Rod

Yarns

thermoplastic

reinforcement fiber

Pultrusion-Extrusion Process (CLF)

*patented technology, pictures can not be published without approval from Martin Eichenhofer

Pultrusion

Extrusion

Martin Eichenhofer


||

Pultrusion-Extrusion Prozess (CLF)

Pultrusion

Extrusion

Q̇

Q̇

Rod

Yarns

*patented technology, pictures can not be published without approval from Martin Eichenhofer

> 10’000 fibers


||

Application Principles

Free Form Printing 3D Printing / AFP Tape Laying

(3D+) (3D) (2D)

P rocess Head

Composite LayupExtrusion

T,V

Process Head

Composite Layup

Extrusion +

Compaction

T,V


||

State of the ArtCLF Robotic Print Systems

§ CF/PA12 Robotic Printer § CF/PEEK Robotic Printer


||

CLF Robotic Print Systems


||

Example:Locally Reinforced Structures (single strand)

Commonly used CF/PEEK sheet

CF/PEEK sheetlocally reinforced with CLF system

§ Qualitative Assessment


||

Example:Locally Reinforced Structures (multiple strands)

multi-layer stacking of individual fiber composite

strandsCF/PEEK stringer-stiffened panel


||

Example:Ultra-Lightweight Structures (<10mg/cm3)

§ Open Lattice Sandwich Panel

CF/PA12 sandwich panel

CF/PEEK sandwich panel


||

Example:Ultra-Lightweight Structures (<10mg/cm3)

§ 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


||

Example:Ultra-Lightweight Structures

§ 3-Point Bending Tests

Close Up

o 100% thermoplastic compositeo AM stringer reinforcementso Ultra-lightweight core app. 5 mg/cm3

printed stringer reinforcement

no adhesive bond


||

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)


||

Carbon Factory: Use Case

F

F/2

F/2

1.) 3D Print Plastic

2.) 3D Print Carbon

3.) 3D Print Plastic

PlasticCarbon


||

Main research areas







Take-up

Gathering shoe



||

Rapid Stamp Forming of Thermoplastic Composites

§ State-of-the-art in high volume composite production.§ Use of hybrid intermediate materials.

§ Parallelization:§ Heating out-

side of press.§ Forming and

consolidationin mould.

Intermediatematerial

Dr. Joanna Wong ChristophSchneeberger


||


Heating







||


Heating Forming


Heating







||


Heating Forming Consolidationand solidification


Heating Forming







||



Demolding


Compositepart








||

State-of-the-Art Intermediate Materials

C. Schneeberger, J.C.H. Wong, and P. Ermanni. Hybrid Bicomponent Fibres for Thermoplastic Composite Preforms. Manuscript submitted.19 October 2017Paolo Ermanni DLR Braunschweig 40

||

§ 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 inAlternative Processing Routes§ Automated tape laying, filament winding§ Braiding, knitting, stitching§ Additive manufacturing

Bicomponent Fibers

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.19 October 2017Paolo Ermanni DLR Braunschweig 41

||

§ Implementation of the coating method in-linewith the glass fiber spinning process.

§ One-step process.

§ Enables access to geometrically separate filaments.

Economical In-line Coating Process


||

Method 1: Dip-Coating in Polymer Solution

§ Preparation of single glass filaments of finite length 0.5m to 1m.

§ Fibres drawn through dilute polymer solution.

§ Take-up on winder at constant speed.

Winder

Coatingbath

Fiber


||

Methodology: Dip-Coating in Polymer Solution




Steelring


||

Methodology: Dip-Coating in Polymer Solution




§ Samples investigated using scanning electron microscopy (SEM).§ Imaging of cross-sectional and transverse

views.

Steelring


||

§ 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.

Thermoplastic material: poly(ester-amide)

«Isotropic» liquid «Organized» solid

Source: R. Koopmans, Dow Europe GmbH19 October 2017Paolo Ermanni DLR Braunschweig 46

||

§ Dip-coating of single filaments at controlled speeds.

Experimental Results: Dip-Coating in Solution

C. Schneeberger, J.C.H. Wong, P. Ermanni “Hybrid Bicomponent Fibres: A New Class of PrepregMaterials for Thermoplastic Composites , Submitted.

§ Dip-coating of single filaments at controlled speeds.

§ Different polymer solutions:a. PEA-Chloroformb. PC-Chloroformc. PS-Tetrahydrofurand. PMMA-Tetrahydrofuran

a1 a2 b1 b2

c1 c2 d1 d2


||

Technical Challenge: Realization of In-line Process

Dip-Coating

Glass Fibre

Spinning

in-line

§ 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.

§ Diameters from 10µm to 20µm .§ Coating fluid: PEA-CHCl3 solutions with variable concentration (1.8wt% to 12.3wt%).§ Coating thicknesses resulting in fiber volume fractions between 0.5 and 0.7.


||

§ Glass flows at spinneret/take-up:§ Spinneret: Hagen-Poiseuille flow.§ Take-up: momvement of solid glass.

§ Conservation of mass.

§ Typical processing speeds: ~ 40-60 m/s§ Reported processing speeds: 8-83 m/s§ Achievable processing speeds: 1.15 m/s and higher

Theory: Glass Spinning

𝑄𝑚: volumetric flow rate𝜌𝑔: density of glass𝑔: gravitational accelerationℎ: height of glass melt above spinneret𝑅: flow resistance

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, 26-30th June 2016.

§ Hagen-Poiseuille law inserted:

𝑄9 = 𝑇𝑡𝑣 = 𝜌>𝜋𝑟@𝑣 =𝜌>@𝑔ℎ𝑅


||

§ Coating thickness is a function of viscosity, surface tension, and withdrawal velocity! (Landau-Levich problem)

§ Relation between immediate coating thickness ℎ and 𝑣$:

§ White & Tallmadge’s model:

§ De Ryck & Quéré’s model:

§ Assuming coating from a Newtonian fluid.

Theory: Dip-Coating of Cylinders

ℎ𝑟 =

1.34𝐶𝑎@D

1 − 1.34𝐶𝑎@Dwith𝐶𝑎 =

𝜂𝑣𝛾

ℎ𝑟 =

1.34𝐶𝑎@D

1 − 𝑊𝑒 with𝑊𝑒 =𝜌𝑣@𝑟𝛾

1𝑣$− 1

1 + ℎ𝑟@− 1

=𝜌𝜌M𝑤M


||

• Tallmadge’s model:

§ Dynamic viscosity (power law):

§ àNon-Newtonian fluids.

Theory: Dip-Coating of Cylinders

D, S , Y and G represent dimensionless parameters

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, 26-30th June 2016.

𝜂 = 𝐾�̇�PQR

𝑣 = 1.093

2𝑛 + 1 𝐷𝐶9PV@@P + 𝐺 2𝑌

PVRP 𝛾

1𝐾 𝜌𝑔𝛾

RQP@

RP


||

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).


||

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


||

Kiss-roll Coating Setup

§ Preparation of glass monofilaments:§ Finite lengths < 3m.§ Mean diameter of 12µm.§ Sized with 1wt% 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.§ Solvent: trichloromethane (CHCl3) (Sigma-Aldrich)

Fiber guides

Kiss-rollPolymersolution bath

Drying length

Fiber guide

Take-up winder

Fiber


||

Kiss-roll Coating Demonstration


||

SEM High Speed Trials

§ Fiber velocity:

§ Polymer concentration in solution:

𝑤M = 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 .

𝑉 = 14 ms−1


||

Objective

Identify influence of parameters on:§ Final fiber volume fraction 𝑣$

§ Sensitivity of final fiber volume fraction to fiber speed 𝑣$ vs. 𝑉

§ Parameter study for:§ Polymer concentration in

coating solution 𝒘𝒑

§ Peripheral roll velocity 𝑼§ Roll radius 𝑹

§ Design of experiment:§ Two-level full factorial study

Parameter Unit Lowlevel

Highlevel

𝑤M wt% 8 10

𝑈 m s−1 0.5 1.0

𝑅 m 0.05 0.10

§ High speed trials for fiber speeds 𝑉 up to 14 m s−1.


||

Linear Multivariate Regression

§ Fiber velocity 𝑉 to yield 𝑣$ = 0.7

§ To obtain 𝑣$ = 0.7 at high fiber velocity 𝑉 ↑:

§ Minimize polymer concentration in coating solution 𝒘𝒑 ↓

§ Maximize peripheral roll velocity 𝑼 ↑

§ Maximize roll radius 𝑹 ↑§ Exception: at high 𝑤M

𝑉 = 𝑐p+𝑐R 𝑤M + 𝑐@ 𝑈+ 𝑐D 𝑅+𝑐R@ 𝑤M 𝑈 + 𝑐RD 𝑤M 𝑅 + 𝑐@D 𝑈 𝑅+𝑐R@D 𝑤M 𝑈 𝑅


Acknowledgments

We thank our supporters and collaborators:§ Swiss National Science Foundation

(Project № 200021_165994).§ Swiss Competence Center for Energy Research

(SCCER) Efficient Technologies and Systems for Mobility.

§ Dow Europe GmbH.§ Leibnitz Institute of Polymer Research Dresden.

||

...Thank you for your attention

cfrp-am for individualized, cost -efficient and sustainable ultra-lightweight … · 2017-10-27 ·...

Documents