Single Step Forming and Moulding of Prepreg Composites for use in Automotive Applications
Rachel Weare¹, Fred Walker², Kate Carter², Ken Kendall¹
¹ WMG, The University of Warwick, UK ² Aston Martin Lagonda Ltd, UK SCOPE
WMG and the Automotive Composites Research Centre
The InterCOMP Project
Blank Development
Kit Splits
Conclusions WARWICK MANUFACTURING GROUP
Academic department within the science faculty of the University of Warwick
Established in 1980 to facilitate technology transfer and knowledge creation for industry
Over 800 people in 7 buildings
Training over 2,500 individuals in the UK and abroad
Co-located with Tata Steel, JLR, Tata Motors European Technical Centre & the APC AUTOMOTIVE COMPOSITES RESEARCH CENTRE
Opened 2015
20 staff
Development of CFRP manufacturing technologies for high volume automotive applications
State-of the art, industrial scale composite processing equipment
Equipment development to enhance the ACRC capabilities, particularly automation
Industrial partners include Ford, JLR, AML, Gestamp, GKN, Expert T&A SCOPE
WMG and the Automotive Composites Research Centre
The InterCOMP Project
Blank Development
Kit Splits
Conclusions INTERCOMP
Integrated COmpression Moulding Process
24 month research project co-funded by Innovate UK
Single stage double diaphragm stamp forming process
Existing equipment developed to integrate Double dome process steps geometry
Generic part for characterising formability
Structural components for process development and demonstration INTEGRATED COMPRESSION MOULDING PROCESS
Ply assembly Pressing and joining station Blank transfer
CNC ply Heating cutting station
Ply loading Ply pick robot Ply storage Ply unloading
Shuttle Blank loading direction of station travel DOUBLE DIAPHRAGM STAMP FORMING
Forming
IR Pre-heating Material Loading Curing SCOPE
WMG and the Automotive Composites Research Centre
The InterCOMP Project
Blank Development
Kit Splits
Conclusions BLANK DEVELOPMENT Max. Length Max Width Area BLANK Blank Image BLANK 2 (mm) (mm) (m²) (oversize)
BLANK 1 730 430 0.31 BLANK 4 BLANK 1 (near net-shape)
BLANK 2 770 490 0.32 (oversize)
BLANK 3 0/90º 660 385 0.22 (net-shape from simulation) ±45º 620 390 0.22
BLANK 4 707 400 0.26 (near net-shape) BLANK 3 BLANK 3 ±45º 0/90º (net-shape) (net-shape) QI layup, 4 plies 2x2TW carbon-epoxy prepreg [0/90º, ±45º]s PREDICTING THE NET-SHAPE BLANK
2. Double dome component 1. Oversized blank periphery projected used to simulate onto formed plies double dome forming behaviour
3. Simulation reversed and plies 0/90º undraped to provide ±45º 4. Edges smoothed to a flattened profile give a uniform blank profile avoiding fibre discontinuities ±45º NET-SHAPE BLANK
Only one iteration was required for the double dome geometry
Geometries with more complex peripheries require many iterations
BLANK 2 BLANK 3 (oversize) (net-shape from simulation) PLY NESTING
Software unsuitable for batched runs
~10% decrease in efficiency when batching runs compared to “best-nest”
Efficiency levels off at 10 parts
BLANK 3 (net-shape) uses least material overall
BLANK 3 BATCHED
BLANK 3 BEST NEST ROLL WIDTH
Material efficiency increased by 5% for 1.25m roll
Using BLANK 2 as opposed to BLANK 3 increases material usage by 47% for both roll widths
Material Area per part (m²) Roll Width Blank 1 Part 10 Parts 20 Parts (m) BLANK 2 1.79 1.69 1.69 1.00 BLANK 3 1.34 1.15 1.15 BLANK 4 1.51 1.32 1.31 BLANK 2 1.72 1.61 1.60 1.25 BLANK 3 1.27 1.09 1.09 BLANK 4 1.37 1.26 1.26 MOULDING BLANKS 1 & 2
BLANK 2 BLANK 1 (oversize) MOULDING BLANKS 3 & 4
BLANK 3 BLANK 4 (net-shape) (near net-shape) CORRELATION BLANK 2
Focused correlation on blank 2 moulding to simulation
Portable CMM with a laser line probe attachment
Periphery of the top ply was raised to make it visible on the scan
Scanned part
Simulation prediction CORRELATION BLANK 3
Ply slippage gives early indication for friction correlation
Simulation predicts approximately 2mm slippage between plies compared to 15mm on part
2 mm 15 mm SCOPE
WMG and the Automotive Composites Research Centre
The InterCOMP Project
Blank Development
Kit Splits
Conclusions KIT SPLITS
3 kit-split designs
Improve nesting efficiency
Investigate forming behaviour
Correlate CAE models KIT SPLIT DESIGN 1
Dome 1
0° 385mm -45° 45° Ply 1 and 4 split across part PLY 1 2 3 4 centre-line (orange) 90°
Tracer fibre placed 5mm 0/90 0/90 Dome 2 either side of split (green) ±45 ±45
Illustration on formed 490mm geometry KIT SPLIT DESIGN 2
PLY 1 2 3 4
Ply 1 split across dome 1 Dome 1
(orange) 0° 385mm -45° 45°
0/90 0/90 90° Ply 4 split across dome 2 ±45 ±45 (orange) PLY 1 2 3 4
Dome 2
Tracer fibre placed 5mm either side of split (green) 0/90 0/90 ±45 ±45 Illustration on formed 490mm geometry KIT SPLIT DESIGN 3
PLY 1 2 3 4
Ply 3 split across dome 1 Dome 1
(orange) 0° 385mm -45° 45°
0/90 0/90 90° Ply 2 split across dome 2 ±45 ±45 (orange) PLY 1 2 3 4
Dome 2
Tracer fibre placed 5mm either side of split (green) 0/90 0/90 ±45 ±45 Illustration on formed 490mm geometry KIT SPLIT NESTING x 10
BLANK 2 – 16.91m efficiency: 77%
BLANK 2 KIT SPLIT 1 – 15.75m efficiency: 83%
BLANK 2 KIT SPLIT 2 – 15.43m efficiency: 84%
BLANK 2 KIT SPLIT 3 – 15.39m efficiency: 84% KIT SPLIT NESTING
Kit split 3 most material efficient; reduction of 10%
Kit splits improve material efficiency, BUT at what
penalty?
Length per part (m) Blank 1 Part 10 Parts 20 Parts BLANK 2 1.79 1.69 1.69 BLANK 2 KIT SPLIT 1 1.64 1.58 1.58 BLANK 2 KIT SPLIT 2 1.57 1.54 1.54 BLANK 2 KIT SPLIT 3 1.58 1.54 1.54 KIT-SPLIT MOVEMENT
Where plies separate, resin flows to fill the void and washes fibres
Constant thickness – varying fibre volume content
Internal split areas are easily identified by resin richness on part surface
KIT SPLIT 1 KIT SPLIT 2 KIT SPLIT 3
Centre (outer) Centre (underside) Dome 1 (outer) Dome 2 (outer) Dome 1 (outer) Dome 2 (outer) PREDICTING KIT SPLIT MOVEMENT
Kit split behaviour predicted through CAE forming analyses
Simulations predicted ply separation at the butt joint
Analysis important for FEA correlation
Ply slippage data used to correct model friction
KIT SPLIT 1 KIT SPLIT 2 KIT SPLIT 3 (ply 1 shown) (ply 1 shown) (ply 2 shown) CORRELATION
1 2 3 Dome 1
4 5 6 Centre
7 8 9
Dome 2 Separation Distance Separation Distance (mm)
Illustration on formed geometry SCOPE
WMG and the Automotive Composites Research Centre
The InterCOMP Project
Blank Development
Kit Splits
Conclusions CONCLUSIONS
Excess material can exacerbate wrinkling
Blank optimisation increases material efficiency
The simulated net-shape blank does not produce a true net-shape part and using a net-shape part will not increase material efficiency if the entire part is to be scrapped!
Simulation models needs improving to account for ply interactions (friction and interface)
Blank positioning must be improved to mould net-shape components
Kit splits most material efficient but are unpredictable
Geometry specific Any Questions?
Thank you for listening
Rachel Weare [email protected]