www.bris.ac.uk/composites

New approaches in composites manufacture

ByungChul (Eric) Kim

B.C.Eric.Kim@bristol.ac.uk

2/11

Innovation in composites manufacturing

• MfD (Manufacturing for Design)

vs. DfM (Design for Manufacturing)

• New approaches in

• These examples show how new manufacturing methods can maximise the material efficiency by minimising process-induced defects.

Compression moulding Composite spherical bearing

Automated fibre placement Continuous tow shearing

Forming Low-temp drape forming

3/11

What if we can form the composite race around

the ball without machining ?

Composite Spherical Bearing

< Seizure problem of metal bearings >

< Bearings requiring complex machining >

US2008/0289183 - Apparatus and method for manufacturing spherical bearing assembly

Vf = 55~60%

1

4

4/11

Composite Spherical Bearing

Laboratory endurance test- Development of in-house endurance tester

0

100

200

300

400

500

600

0 100 200 300 400 500

Cycles

Fri

ctio

n t

orq

ue

(Nm

)

Without loading( 0.1 Hz )

Seizure

Metal bearing

CSB

Bearing surface (200,000 cycles)

• Non-seizure property

• Low friction torque without bearing clearance

• Through-thickness compressive strength: 1.2 GPa

5/11

What if we can fundamentally change the tow

deformation mechanism ?

Continuous Tow Shearing

• Increased demand for more complex fibre orientation design and part geometry

Tow steering capability of AFP machines

• All modern AFP machines produce defects in tow steering.

Wrinkling and folding(Steering R: 40~100 mm)

AFP

NLR

In-plane bending

No fibre wrinkling(Steering R: 50 mm)

CTSIn-plane

shear

6/11

Continuous Tow Shearing

GB2492594 – Tow placement apparatus and method

Compaction shoe

Tow feeding roller

Gripping shoe

dx < 1 mm

Layup accuracy±2°200 mm qmax=70°

qmax=60°

qmax=50°

qmax=40°

qmax=30°

qmax=20°

qmax=10°

R 80 mm

7/11

Continuous Multi-tow shearing

• No coupling between the tape width and the steering radius

• Process flexibility

- Dry fabric + resin film RFI

- Dry fabric + binder RTM

90 mm wide UD fabric (40 tows)

Automated Tape Laying with exceptional steering capability

8/11

Low-temperature drape forming

High

interfacial

friction

• For relatively simple geometry, drape forming is more efficient.

• Interply friction (or tackiness) prevents the ply slippage.

Major challenge in the drape

forming of thick preforms

What if we can allow slippage during

forming by applying interleaving

materials at low temperature ?

Interleaving layers

(Powder/Veil)

9/11

Low-temperature drape forming

< Interply friction measurement rig >

PowderVeil

Non-interleaving

Reduction of forming temperature

Interlaminar toughness improvement

10/11

Conclusions and Future

• The process-induced defects in composites manufacturing limit the potential of novel designs and materials.

• The defect generation mechanisms are complex, which increases the gap between design and manufacturing engineers

• This makes the DfM very challenging. And in many cases, design modification cannot actually avoid the defects. (e.g. AFP on complex geometry, tow steering)

• We already established a complete defect taxonomy.

• Now, we need to focus on identifying the fundamental limitations of current manufacturing methods and invest more time and resources to find new manufacturing solutions for MfD.

11/11

Evangelos Zympeloudis

Acknowledgement of support from the EPSRC CDT programme

With thanks to the co-supervisors; Kevin Potter, Paul Weaver, Hana Yu

LoganWang