DES tech Publications, Inc. PRINCIPLES of the MANUFACTURING OF COMPOSITE MATERIALS Suong V. Hoa Department of Mechanical and Industrial Engineering Concordia University, Quebec, Canada Principles of the Manufacturing of Composite Materials DEStech Publications, Inc. 439 North Duke Street Lancaster, Pennsylvania 17602 U.S.A. Copyright © 2009 by DEStech Publications, Inc. All Rights Reserved No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. Printed in the United States of America 10987654321 Main entry under title: Principles of the Manufacturing of Composite Materials A DEStech Publications book Bibliography: p. Includes index p. 337 ISBN: 978-1-932078-26-8 Contents Preface vii Acknowledgements ix PART 1—FUNDAMENTALS OF CONSTITUENTS FOR COMPOSITES MANUFACTURING 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Examples of Products Made Using Different Manufacturing Techniques 3 General Characteristics of Manufacturing Using Composites 13 Functions of the Constituents of Composites 19 References 41 Appendix 41 Homework 43 2. Matrix Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Introduction 45 Different types of Matrix Materials and Their Prominence 45 Thermoset Matrix Materials 50 Thermoplastic Matrix 90 Fillers, Colorants and Other Resin Modifiers 95 Ceramic Matrices 96 Metal Matrix 96 References 97 Homework 97 3. Reinforcements—Fibers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 General 99 Individual Filaments 100 v Tows 115 Fabrics and Other Reinforcement Forms 116 Deformation of a Bed of Fibers 123 References 136 Homework 72 Part 2—TECHNIQUES FOR COMPOSITES MANUFACTURING 4. Hand Laminating (or Wet Lay-up) and the Autoclave Processing of Composites . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 Hand Laminating (or Wet Lay-Up) 141 Autoclave Processing 143 References 202 Homework 204 5. Filament Winding and Fiber Placement . . . . . . . . . . . . . . . . 205 Filament Winding 205 Fiber Placement Process 230 References 231 Homework 231 6. Pultrusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233 General 233 Materials 235 Combination of Other Processes with Pultrusion 238 Factors Affecting the Pultrudability of a Composite Component 143 Summary 244 Reference 246 7. Liquid Composite Molding. . . . . . . . . . . . . . . . . . . . . . . . . . . 247 Introduction 247 Materials 255 Mold Filling 262 In-Mold Cure 283 References 287 Homework 287 8. Long Fiber Thermoplastic Matrix Composites. . . . . . . . . . . 289 Introduction 289 Materials 291 Preliminary Material Combinations (PMCs) 293 Fabrication of the Final Product 301 References 181 Index 337 About the Author 343 vi Contents PART 1 Fundamentals of Constituents for Composites Manufacturing CHAPTER 1 Advanced composite materials have been used to fabricate many structural parts in engineering applications. This is due to their many at- tractive characteristics such as light weight, high strength, high stiffness, good fatigue resistance and good corrosion resistance. Also, the ability to manufacture parts with complicated geometry using fewer compo- nents enables manufacturers to save cost as compared with the same parts made of conventional metallic materials. Before presenting the fun- damental aspects of manufacturing and different techniques used for composites manufacturing, it is appropriate to present composite struc- tural parts currently in use and the main techniques that have beenused to fabricate them. 1. EXAMPLES OF PRODUCTS MADE USING DIFFERENT MANUFACTURING TECHNIQUES Figure 1.1(a) shows a schematic of an Airbus 380 airplane (the largest airplane in the world as of 2008). This airplane has more than 50% of its structure made of composite materials. These components include the flaps, ailerons, rudder, radome etc. Most of these components are flat in shape and they are usually made using hand-lay-up (HLU) and autoclave molding techniques. Figure 1.1(b) shows a schematic of the hand-lay-up fabrication technique and a representative lay-up sequence. Autoclave molding is a well-established method for composites used in the aero- space industry with certified resins and fibers. A photograph of an auto- clave is shown in Figure 1.1(c). Autoclave Molding will be discussed in detail in Chapter 4. 3 FIGURE 1.1(a) Airbus 380 with its composite component (from http://www. specialchem4adhesives.com/home/editorial.aspx?id=752). FIGURE 1.1(b) Schematic of the hand-lay-up fabrication method and a representative lay-up sequence. Individual layers can be cut by hand or by a computerized machine cut- ter. The layers can be stacked one on top of the other by hand or by a robot. 4 Figure 1.2(a) shows a pressure vessel made of composite materials us- ing the combination of hand-lay-up and filament winding processes. Composite pressure vessels are light weight and can contain pressures higher than those contained by metallic vessels. These components are made using the filament winding process [Figure 1.2(b)]. Figure 1.2(c) shows a photograph of a filament winding machine. The filament wind- ing process will be discussed in detail in Chapter 5. 5 Examples of Products Made Using Different Manufacturing Techniques FIGURE 1.1(c) Photograph of an autoclave (courtesy of ASC Ltd.). FIGURE 1.2(a) Composite pressure vessel made by combination of hand-lay-up and filament winding. FIGURE 1.2(b) Schematic of the filament winding process (courtesy of Wiley Interscience). FIGURE 1.2(c) A two-spindle winder with a carriage-mounted resin bath and a free- standing creel in the background (courtesy of Composites Technology magazine, August 2005). 6 Figure 1.3(a) shows a component made using pultrusion. Pultrusion is used to make many structures for civil engineering applications. Figure 1.3(b) shows the schematic of the pultrusion process, and Figure 1.3(c) shows a photograph of a lab scale pultrusion machine. Pultrusion will be discussed in Chapter 6. Figure 1.4(a) shows a composite component made using the liquid composite molding (LCM) method (5 piece). LCM has been used to make automobile composite components. Figure 1.4(b) shows a sche- matic of the liquid composite molding process and Figure 1.4(c) shows a pump, a mold and accessories for the liquid composite molding hard- ware. Liquid composite molding will be discussed in Chapter 7. 7 Examples of Products Made Using Different Manufacturing Techniques FIGURE 1.3(a) A composite pultruded connector. FIGURE 1.3(b) Schematic of the pultrusion process (courtesy of Springer). [...]... and left of the cracked fiber increases by 8% (0. 02 N) due to occurrence of the crack in the middle fiber, the maximum stress in the remaining fibers can be as follows: Fiber 1: 1 .25 /5 = 0 .25 N Fiber 2: 0 .25 + 0. 02 = 0 .27 N Remaining of Fiber 3: Less than 1 .25 /5 = 0 .25 N (assumed to be 0 .21 N) Fiber 4: 0 .25 + 0. 02 = 0 .27 N Fiber 5: 0 .25 N Total sum = 1 .25 N (The lower stress in fiber 3 is due to the... Composites 25 a When the total load P reaches 1 .25 N, the load in each of the fibers is 0 .25 N (1 .25 N/5) This is the load at which fiber 3 breaks b After fiber 3 breaks, only 4 fibers remain to sustain the load of 1 .25 N The average of 1 .25 N over 4 fibers is 0.31 N This load in turn is more than the breaking load of 0.30 N of fiber 1 So fiber 1 breaks and leaves only 3 fibers to sustain the load of 1 .25 ... machine (courtesy of Aerospace Manufacturing Technology Center, National Research Council of Canada) 12 General Characteristics of Manufacturing Using Composites 13 A few specific features can be extracted from the above components and the different manufacturing techniques used to fabricate them Normally structural components can be classified according to their shape, and the manufacturing technique used... straight and a small amount of tension may be required to keep them straight Special techniques and care are required to attain this configuration FIGURE 1.9 Photograph of entangled bunches of fibers Each shows a tow with fibers aligned and fibers that are frayed 22 Functions of the Constituents of Composites 23 3.1 .2. 2 Fibers Need to be Bonded Together to Provide Good Mechanical Properties Fibers used... S11/S 22, is on the same order Figure 1 .20 shows the transverse permeability of an aligned fiber bundle, which is about one twentieth the values as those along the axis of the fibers, as shown in Figure 1.18 FIGURE 1 .20 Transverse permeability of aligned fiber bed Note that the unit for permeability is multiplied by 10−11 cm2, as compared to Figure 1.18 where the unit is multiplied by 10−10 cm2 The... than the breaking load of 0.30 N of fiber 1 So fiber 1 breaks and leaves only 3 fibers to sustain the load of 1 .25 N c The average of 1 .25 N over 3 fibers is 0. 42 N This is more than the breaking load of 0.35 N of fiber 2 so this fiber breaks d The average of 1 .25 N over 2 fibers is 0.63 N This is more than the breaking loads of 0.40 N and 0.50 N of fibers 4 and 5 and therefore these fibers also break... parts such as automobile panels which may be adversely affected by this shrinkage Resins with Low Profile Additives are usually used to control shrinkage 2. 1 Metal versus Composite Manufacturing Manufacturing using composites has differences from manufacturing using metals: • • In metals such as steel or aluminum, materials with finished form such as rods, slabs, or sheets are available The making... 1.14 Micrograph of a cross section of a unidirectional composite sample Functions of the Constituents of Composites 29 FIGURE 1.15 Square array of fibers Based on this arrangement, the fiber volume fraction can be calculated as: vf = Volume of fiber n 2 πd 2 = Total volume 4( nd + nδ ) 2 (1.8) where d is the fiber diameter and δ is the shortest space between two fibers In the limit when the fibers are... illustrate this point, Figure 1. 12 shows again the fiber bundle as in Figure 1.11 but in this case the fibers are bonded together via matrix adhesive FIGURE 1. 12 Bundles of five fibers bonded together via adhesive 26 INTRODUCTION Assume that we also have the same individual fiber failure loads as in Equation (1.7) Now assume that the load is increased slowly from 0–1 .25 N Assume also that the matrix... stress distribution assumption, equal to σ /2 where σ is the tensile strength of the reinforcement material and τ is the shear bond strength between the 20 INTRODUCTION reinforcement and the matrix), failure will occur due to slipping between the reinforcement and the matrix, making the reinforcement ineffective For the case of glass/epoxy where σ = 3448 MPa and τ = 20 .5 MPa, the critical aspect ratio is . . . . 24 7 Introduction 24 7 Materials 25 5 Mold Filling 26 2 In-Mold Cure 28 3 References 28 7 Homework 28 7 8. Long Fiber Thermoplastic Matrix Composites. . . . . . . . . . . 28 9 Introduction 28 9 Materials. 143 References 20 2 Homework 20 4 5. Filament Winding and Fiber Placement . . . . . . . . . . . . . . . . 20 5 Filament Winding 20 5 Fiber Placement Process 23 0 References 23 1 Homework 23 1 6. Pultrusion . . . . . . 23 3 General 23 3 Materials 23 5 Combination of Other Processes with Pultrusion 23 8 Factors Affecting the Pultrudability of a Composite Component 143 Summary 24 4 Reference 24 6 7. Liquid