Textile Preforms

V.P.Senthilkumar11MT71

Production Technologies for Composites

Non-crimp fabrics (NCF)

Prepregging

Braids

3D-preforming

OverbraidingITA

NCF machine NCF

Strategies for Future Preforming

• Tailored Braids

• Tailored NCFs

• Automated Preform Assembly

Preforming technology

The three major challenges for the production of textile preforms

• Reduction of cycle times

• Reduction of costs

• Production of complex parts in large

numbers

BMW I3 car body

Motivation for Research in Composites

• Fiber reinforced plastics (FRP) are a promising engineering material for:

• Aerospace• Automotive industry• High-end machine parts• Wind energy

Motivation for Research in Composites

Why FRP for conventional vehicles?

• Emissions: 100 kg car weight ≈ 9 g CO2 per km[2] • Fuel consumption: 100 kg car weight ≈ 0.4l per 100 km[2] • Improved safety • Higher accelerations

Why FRP for electrically driven vehicles?

• Critical distance range • Expensive batteries • Integration of functionality

1. Source BMW

2. Source Audi

Motivation for Research in Composites

The production of FRP parts in high volume can be realised by means of Preforming-Liquid Composite Moulding (LCM) processes

• Short cycle times

• Heavy tow material can be used

• Complex designs

• High amount of manual labour

For composite materials, there is a close interaction Between * Production processes * Part design * Material properties

Future Preforms

WeavingWeaving NCFNCFBraidingBraiding

RovingRoving

Fibre placement

Fibre placement

Multi step preform

Multi step preform

Preform assemblyPreform assembly3DPreform

3DPreform

3D Weaving3D Weaving

3DPreform

3DPreform

Single-step preforming

Multi-step preforming

Strategy For Future Preforms

• Combination of single-step and multi-step preforming

• Single-step: Production tailored textiles with locally adjusted properties

• Multi-step: Automated assembly of tailored textiles into complex preforms

Single-step preforming(Tailored-NCF)

Tailored-Braid Multi-step preforming

Pref

orm

ing

Tailored Blank Tailored Tube Assembly line

Source: Thyssen Krupp Source: Thyssen Krupp

Stee

l pr

oces

sing

Source: KUKA

Single-step preforming(Tailored-NCF)

Tailored-Braid Multi-step preforming

Pref

orm

ing

Tailored Blank Tailored Tube Assembly line

Source: Thyssen Krupp Source: Thyssen Krupp

Stee

l pr

oces

sing

Source: KUKA

Tailored Braids

Process Overview

Roving

(3D Fiber Weaving) placement

3D sub-preform

Braiding

Preform assembly

Multi-step preform

Warp-Weaving knitting

2D preform

Tailored braids

• Overbraiding technology

Two groups of bobbins moving on concentric circles

Mandrel is moved through braiding eye

Tubular braid is laid down on shaped mandrel

Bobbin path in radial braiding

ITA

Radial braiding machine

Tailored braids

• Overbraiding technology

Economic production of near-net shape textile preforms

0°-layers possible

Automation possible

Wide range of materials

Braiding of ceramic fibers Braiding of 0°-layer

Tailored braids

• 3D-rotary braiding technology• Independent bobbin movement• Highly complex structures• Fully interlaced structures

Tailored braids

Examples for 3D-rotary braids

3D-braided T-profile Preform for crash-absorber with integrated flange

10 mm

Continuous change of cross section 3D-braided branching

16

Tailored braids

Challenges braiding technology

• High productivity

• Complex geometries

• No continuous production

if thickness changes

• More possibilities in

production than in

simulation

• Simulation

• Mechanical parameters

• Design tools

• Modification of thickness

• Braiding speed

Tailored NCFs

Process Overview

Roving

(3D Fiber Weaving) placement

3D sub-preform

Braiding

Preform assembly

Multi-step preform

Warp-Weaving knitting

2D preform

Tailored NCFs

Multiaxial non-crimp fabrics (NCFs)

0°-Layer supply

Creel for rovings

Production direction

Take-up

Warp-knitting unit

Computer controlled weft-insertion-systems

Warp-knittting machine [LIBA Maschinenfabrik GmbH]

Tailored non-crimp fabrics

Production of near-netshaped semi-finished parts in one production process

Non-crimp fabrics (NCF) with

locally adjusted properties

allowing different

• Thickness

• Bending stiffness

• Drapability

Benefits for preforming

• Less cutting operations

• Less cutting waste (up to 60 %)

• Less handling operations

Schematic structure of multiaxial warp-knit

[LIBA GmbH]

Automated preform assembly

WeavingWeaving NCFNCFBraidingBraiding

RovingRoving

Fiber placement

Fiber placement

Multi step preform

Multi step preform

Preform assemblyPreform assembly3DPreform

3DPreform

(3D Weaving)

(3D Weaving)

3DPreform

3DPreform

Automated

Automated preform assembly

HandlingDrapingHandlingDraping

Quality controlQuality control

CuttingCutting AssemblingAssembling

preform centre

7 m

5 m

Automated preform assembly – step 1: 3-D cutting

Robotically guided cutting device Ultrasonic knife Cutting of complex geometries

Robot

TextileKnife

Housing

Ultrasonic 3D-cutter

Automated preform assembly – step 2: handling

Needle grippers

Cryo grippers

Vacuum technology

Needle gripper Cryo gripper Vacuum technology

Pick and place operation at preform centre

Automated Preform Assembly – step 3: quality control

Online quality control Texture (material, textile type) Orientation and geometry of textiles Defects in textiles

Monitoring head

Lighting module

Lasersensor

Casing

Camera

Robot flange

Interface

Digital image processing

Automated preform assembly – step 4: assembling

Sewingtechnology

SewingKSL-tufting

SewingKSL-blind stitch

BinderHot melt

Automated Preform Assembly

Tailored binder application • Robotically guided

• Local application

• Different binder materials

• Varying binder quantities Local binder application

Novel binder activation • Activation by hot air

• Compression of preform

• Robust system with low invest

• Modular system

Novel binder activation device

Automated Preform Assembly

Exemplary process chain for the automated production

of binder-preforms

Loop

cutting handling Binder

application Binder

handling activation

Summary

Automated preforming process vs. existing technologies: Lower cycle times Less waste (down by 60 %) Lower costs Complex parts in large numbers

→Mass production of composites

Properties of some textile performs

Textile Preform

Advantage Limitation

Low crimp, uniweave

High in-plane properties; good taliorability; highly automated preform fabrication process

Low transverse and out-of-plane properties; poor fabric stability; labor intensive ply lay-up

2-D Woven Good in-plane properties; good drapability; highly automated perform fabrication process; integrally woven shapes possible; suited for large area coverage and extensive data base

Limited taliorability for off-axis properties ; low out-of-plane properties

Properties of some textile performs

Textile Preform

Advantage Limitation

3-D Woven Moderate in-plane and out-of-plane properties; automated preform fabrication process and limited woven shapes are possible

Limited taliorability for off-axis properties and poor drapability

2-D Braid Good balance in off-axis properties; automated preform fabrication process; well suited for complex curved shapes; good drapability

Size limitation due to machine availability and low out-of-plane properties

Properties of some textile performs

Textile Preform Advantage Limitation

3-D Braid Good balance in in-plane and out-of-plane properties; well suited for complex shapes

Slow preform fabrication process; size limitation due to machine availability

Multi-axial warp knit Good taliorability for balanced in-plane properties; highly automated preform fabrication process; multi-layer high throughput; material suited for large area coverage

Low out-of-plane properties

Stitched fabrics Good in-plane properties; highly automated process; provides excellent damage tolerance and out-of-plane strength and excellent assembly aid

Small reduction in in-plane properties; poor accessibility to complex curved shapes