Composite Technology : Prepregs and Monolithic Part Fabrication Technologies

Prepreg materials are pre-impregnated fibers for the manufacture of composite components, and are widely applied in the wind energy and aerospace industries. The properties of these semi-finished products, the type of processing, and the component design collectively play an important role in the quality and suitability for mass production of a fiber composite component. The book provides a holistic approach, showing the influence and mutual interaction of the parameters involved in the production of fiber composite components. Current state of prepreg technology, generation, and development as well as their variations and trends Fundamentals of prepreg preparation and starting materials Processing technology and automation Interactions between construction/design and material and between tooling material and composite components/design Testing of prepreg semi-finished products and components; typical error patterns

Author Notes

Dr.-Ing. Hauke Lengsfeld is Technical Support Manager at Hexcel Composite GmbH, Germany.

Dr.-Ing. Felipe Wolff-Fabris is Director of the European Center for Dispersion Technology at the German Plastics Center (SKZ).

Dipl.-Phys. Johannes Krämer is a researcher at BASF SE, Germany.

Dr.-Ing. Javier Lacalle is Project Manager and Technical Advisor at M.Torres Deutschland GmbH, Germany.

Prof. Dr.-Ing. Volker Altstädt is Director of the the Polymer Engineering Department at the University of Bayreuth, Germany.

Felipe Wolff-FabrisFelipe Wolff-Fabris and Hauke Lengsfeld and Johannes KrämerHauke Lengsfeld and Mike TurnerHauke Lengsfeld and Javier LavalleFelipe Wolff-FabrisHauke Lengsfeld and Hilmar ApmannJohannes KrämerHauke Lengsfeld

Preface	p. v
Acknowledgements	p. vii
Abbreviations and Important Terms	p. xiii
1 Introduction	p. 1
1.1 Materials	p. 1
1.2 Continuous Fiber Reinforced Plastics	p. 4
1.2.1 Property Profile	p. 4
1.2.2 Manufacturing	p. 6
1.2.3 Applications	p. 8
1.3 References	p. 9
2 Prepregs and Their Precursors	p. 11
2.1 Structure and Preparation	p. 13
2.2 Matrix Systems	p. 15
2.3 Fibers and Textiles	p. 18
2.4 Prepreg Systems	p. 20
2.5 References	p. 25
2.6 Additional Information	p. 25
3 Prepreg Technology	p. 27
3.1 Historical Background	p. 27
3.2 Introduction: Manufacturing Methods	p. 29
3.2.1 Design of a Prepreg Production Line	p. 31
3.2.2 Prepreg Manufacturing Methods	p. 31
3.2.2.1 Hot Melt Processes	p. 31
3.2.2.2 Solvent Coating/Solvent Dip Method	p. 36
3.2.3 Prepreg Variations	p. 38
3.2.3.1 Slit Tape	p. 38
3.2.3.2 TowPregs	p. 39
3.2.4 Effect of Manufacturing Parameters	p. 39
3.2.4.1 Resin Content	p. 40
3.2.4.2 Level of Impregnation	p. 41
3.2.4.3 Tack (Tackiness)	p. 43
3.3 References	p. 45
4 Prepregs: Processing Technology	p. 47
4.1 Introduction	p. 47
4.2 Cutting of Prepregs	p. 50
4.2.1 Manual Cutting	p. 50
4.2.2 Automated Cutting	p. 51
4.3 Hand Lay-up of Prepregs	p. 55
4.4 Automated Laying Systems: Automated Tape Laying (ATL) and Automated Fiber Placement (AFP)	p. 57
4.4.1 Introduction	p. 57
4.4.1.1 Goal of Automated Lay-up Processes	p. 59
4.4.1.2 Principle Process Steps of Automated Lay-up Technologies	p. 60
4.4.1.3 Prepregs for Automated Lay-up Processes	p. 64
4.4.1.4 Machine Architecture	p. 68
4.4.2 Automatic Tape Laying (ATL)	p. 72
4.4.2.1 Introduction	p. 72
4.4.2.2 Prepreg Materials for ATL	p. 72
4.4.2.3 General Principle of ATL Processes	p. 74
4.4.2.4 ATL Technology and Major Sub-systems	p. 76
4.4.2.5 Selection of Machine Configuration for ATL Processes	p. 78
4.4.3 Automatic Fiber Placement (AFP)	p. 83
4.4.3.1 Introduction	p. 83
4.4.3.2 Prepreg Materials for AFP	p. 84
4.4.3.3 Governing Principle of AFP Processes	p. 85
4.4.3.4 AFP Technology and Relevant Sub-systems	p. 87
4.4.4 Productivity and Cost Effectiveness of Lay-up Processes	p. 95
4.4.4.1 Lay-up Productivity	p. 95
4.4.4.2 Cost Effectiveness of Automated Lay-up Processes	p. 98
4.5 Pultrusion	p. 100
4.6 Hot Drape Forming	p. 104
4.7 Same-Qualified-Resin-Transfer-Molding Processes (SGRTM)	p. 111
4.8 References	p. 113
4.9 Additional Information	p. 113
5 Curing Technologies	p. 115
5.1 Fundamentals of the Curing Cycle	p. 115
5.2 Autoclave Curing	p. 119
5.3 Oven Curing	p. 122
5.4 Quickstep™ Technology	p. 123
5.5 Press Molding/Forming Processes	p. 125
5.6 Induction Processes	p. 126
5.7 Microwave Curing	p. 127
5.8 Electron Beam Curing	p. 130
5.9 References	p. 134
6 Tooling Technology	p. 135
6.1 Requirements	p. 136
6.2 Tooling Materials	p. 138
6.2.1 Metals	p. 139
6.2.2 Fiber Composite Materials GFRP/CFRP	p. 141
6.2.3 Other Materials	p. 145
6.3 Manufacture of Tools	p. 146
6.3.1 Direct Manufacturing of Forming Tools	p. 147
6.3.2 Indirect Manufacturing of Forming Tools	p. 148
6.4 Tooling Concepts and Examples	p. 151
6.4.1 Hot Forming Tools	p. 151
6.4.2 Curing Molds	p. 153
6.4.2.1 Open Mold Curing Tools	p. 157
6.4.2.2 Closed Mold Curing Tools	p. 158
6.4.3 Release Agents and Cleaning	p. 158
6.5 Additional Information	p. 159
7 Testing of Prepregs	p. 161
7.1 Characterization of the Uncured Prepreg	p. 162
7.1.1 Prepreg Areal Weight, Resin Content, and Fiber Areal Weight	p. 162
7.1.2 Resin Flow	p. 162
7.1.3 Tack	p. 164
7.1.4 Drapability	p. 165
7.1.5 Volatiles	p. 165
7.1.6 Viscosity	p. 166
7.1.7 Water Pickup Test (WPU Test)	p. 168
7.1.8 Microscopy Cut Edge Test	p. 168
7.2 Characterization of the Cured Prepreg	p. 169
7.2.1 Fiber Volume Content	p. 169
7.2.2 Determination of Glass Transition Temperature	p. 171
7.2.3 Cured Ply Thickness (CPT)	p. 172
7.3 References	p. 173
8 Design and Production	p. 175
8.1 Design Concepts	p. 175
8.1.1 Positive/Negative Design	p. 175
8.1.2 Integral/Differential Design	p. 177
8.1.3 Open Mold Concepts	p. 180
8.2 Determining Factors and Interactions	p. 185
8.2.1 Determining Factors during Component Manufacturing	p. 185
8.2.2 Interrelations during Component Manufacturing	p. 187
8.3 References	p. 196
Conclusion	p. 197
The Authors	p. 199
Index	p. 201

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