1、PROGRESS IN TECHNOLOGY SERIES Design of Automotive Composites Y. Charles Lu Srikanth Pilla AUTOMOTIVEDesign of Automotive CompositesOther SAE books of interest: Automotive Carbon Fiber Composites: From Evolution to Implementation By Jackie D. Rehkopf (Product Code: T-124) Engineered Tribological Com
2、posites: The Art of Friction Material Development By Roy L. Cox (Product Code: R-401) Dictionary of Materials and Testing, Second Edition By Joan Tomsic (Product Code: R-257) For more information or to order a book, contact: SAE INTERNATIONAL 400 Commonwealth Drive Warrendale, PA 15096 Phone: +1.877
3、.606.7323 (U.S. and Canada only) or +1.724.776.4970 (outside U.S. and Canada) Fax: +1.724.776.0790 Email: CustomerServicesae.org Website: books.sae.orgDesign of Automotive Composites Edited by Y . Charles Lu and Srikanth Pilla Warrendale, Pennsylvania, USA Copyright 2014 SAE International eISBN: 978
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8、be sought. ISBN-Print 978-0-7680-8132-9 ISBN-PDF 978-0-7680-8138-1 ISBN-epub 978-0-7680-8140-4 ISBN-prc 978-0-7680-8139-8 To purchase bulk quantities, please contact SAE Customer Service e-mail: CustomerServicesae.org phone: +1.877.606.7323 (inside USA and Canada) +1.724.776.4970 (outside USA) fax:
9、+1.724.776.0790 Visit the SAE Bookstore at books.sae.org 400 Commonwealth Drive Warrendale, PA 15096 E-mail: CustomerServicesae.org Phone: +1.877.606.7323 (inside USA and Canada)+1.724.776.4970 (outside USA) Fax: +1.724.776.0790v Table of Contents Introduction . vii Body Structures 1 System Level De
10、sign Simulation to Predict Passive Safety Performance for CFRP Automotive Structures (2013-01-0663)3 Research of Multi-Axial Carbon Fiber Prepreg Material for Vehicle Body (2011-01-0216) 17 Glass-Reinforced Thermoplastic Composites for Front End Module Applications (2011-26-0053) 23 Powertrain Compo
11、nents . 29 Structural Analysis of Steering System Components Considering the Anisotropic Material Properties of Carbon Fiber Reinforced Plastic (2013-01-0019) .31 Development of Intercooler Plastic Tank Material Instead of Aluminum Die-Cast (2013-01-1175) 37 2013 SRT Viper Carbon Fiber X-Brace (2013
12、-01-1775)45 Wear of Glass Fiber Reinforced Polyamide Worm Gear According to the Direction of the Glass Fiber (2010-01-0917) .53 Suspension Components . 62 Design and Fatigue Life Comparison of Steel and Composite Leaf Spring (2012-01-0944) 65 Development of a Lightweight CFRP Coil Spring (2014-01-10
13、57) 71 Electric and Alternative Vehicle Components 77 Development of Polymer Composite Battery Pack Case for an Electric Vehicle (2013-01-1177) 79 Composite Gas Cylinders for Automotive Vehicles Current Status of Adoption of Technology and Way Forward (2013-26-0074) 87 About the Editors 99vii Introd
14、uction Structural materials are generally divided into four basic categories: metals, ceramics, polymers, and composites. This scheme is based primarily upon the microstructures and chemical makeups of the materials 1-1. Metals are combinations of metallic elements and contain nonlocalized electron
15、. Metals, including steels and nonferrous metals such as aluminum, are generally strong and yet deformable. Ceramics are compounds of metallic and nonmetallic elements. They are highly crystalline oxides, nitrides, or carbides, and therefore are very stiff and brittle. Polymers are composed of very
16、large molecular chains of carbon atoms that are side-bonded with various atoms or radicals. The long molecular chains are mostly bonded with weak van der Waals forces, which make polymers neither as strong nor as stiff as metals or ceramics. However, the long molecular structures provide polymers wi
17、th high flexibility. Composites are artificially produced materials that consist of two or more separate materials combined in a macroscopic structural unit. Unlike these traditional materials (metals, ceramics, and polymers) whose microstructures are relatively fixed, composites are highly tunable
18、from microstructure and mechanical properties points of view. As a result, composites can have a desirable combination of the best properties of the constituent phases, meaning they can be strong and ductile, stiff, and lightweight. Composites have been successfully used in aerospace and space indus
19、tries and are gaining momentum in the automotive industry. With a yield strength of more than ten times that of steel or aluminum, and a density of only about one-fifth that of steel and one-half that of aluminum, composites have become the top choice for producing lightweight vehicles 1-2. Accordin
20、g to the U.S. Department of Energy, the transportation sector accounts for 28% of total U.S. energy use, two-thirds of the nations petroleum consumption, and a third of the nations carbon emissions 1-3. Further, the transportation industry accounts for nearly 32% of U.S. greenhouse gas emissions 1-4
21、. It is known that the fuel consumption is directly related to the vehicle weight 1-5. Reductions in vehicle weight can be achieved by a combination of (1) vehicle downsizing, (2) vehicle redesign and contents reduction, and (3) material substitution 1-6. Among these three options, substituting heav
22、y metallic materials with strong and light composites seems to be the most viable choice. The benefits of composites go far beyond weight savings. Polymer matrix composites have great potential for part Materials Modulus of Elasticity (GPa) Ultimate Strength Density (g/cm3) (GPa) E-glass fiber 73 3.
23、4 2.5 S-glass fiber 86 4.5 2.4 PAN-based carbon fiber 230-595 1.9-6.2 1.8 Pitch-based carbon fiber 170-980 2.3-4.1 2.0 Aluminum 70 0.1 2.7 Steel 200 0.4 7.8 Table 1.1: Typical properties of reinforcement fibers and traditional materials 1-10 1-11 integration, which will result in lower manufacturing
24、 costs and faster time to market. The composite parts can have much smaller tooling costs as compared to metal ones. Composites also have much better corrosion resistance than metals and are more resistant to damage, such as dents and dings, than aluminums. Polymer composites possess superior viscoe
25、lastic damping and thus provide improved noise, vibration, and harshness (NVH) performance to the vehicles. Composites also have a high level of styling flexibility in terms of deep drawn panel, which goes beyond what can be achieved with metal stampings. Although the benefits of composites are well
26、 recognized by the industry, the use of composites has been hampered by numerous factors. These mainly include the high costs associated with raw materials and manufacturing and also the lack of design knowledge with composites 1-7 1-8. The automotive industry has traditionally worked with isotropic
27、 materials such as steels and aluminums. For anisotropic composites, there is a dearth of design data (material property database), design tools (models), testing methods, and finally the design examples. This book focuses on the design aspects of the composite materials. It begins with a brief intr
28、oduction to composite materials and design process and then presents some of the most recent, innovated design examples of composite structures by engineers from the automobile OEMs and top-tier suppliers. Basic Concepts of Composite Materials A composite is a material system that is consisted of tw
29、o or more phases on a macroscopic scale, whose performance and properties are much superior to those of the constituent materials acting independently 1-9. The stronger and discontinuous phase is called reinforcement fibers, and the weaker and continuous phase is called resin/matrix. The most common
30、 types of composites are glass or carbon fiber reinforced polymer matrix composites, which are of interest to the automotive sector. Fibers are the principal load-carrying members in the composites. The mechanical properties of glass and carbon fibers are comparable or better than those of aluminums
31、 and steels (Table 1.1). After combining with low-density polymer resins, composites possess superior mechanical properties viii with tremendously high specific modulus and specific strength (Figure 1.1). Unlike the traditional materials (metals, polymers, and ceramics), whose microstructures and pr
32、operties are relatively fixed, composite materials can be highly designable. The structure, and the resultant mechanical properties, of the composites can be easily tailored by adjusting the following: (1) types of fibers, (2) types of polymer resins, (3) fiber volume fractions, (4) lamina types, an
33、d (5) lamina stacking sequence. Reinforcing fibers can be glass, carbon, or other forms. Glass fibers are low-cost materials and typically used when low- to medium-performance composites are needed. Carbon fibers are manufactured from precursor materials, including polyacrylonitrile (PAN) or petrole
34、um pitch. Depending on the processing conditions, the fibers can have different carbon contents, which result in either carbon fibers or graphite fibers. Carbon fibers generally have a carbon content of 8095%, whereas the graphite fibers can have a carbon content exceeding 99%. Graphite fibers have
35、an ultra-high stiffness with modulus over 400 GPa, twice higher than that of steel. Due to their high stiffness and low densities, carbon/graphite fibers are predominantly used when high-performance composites are required. From a weight reduction point of view, it has been estimated that the use of
36、 glass fiber composites can lower the vehicle mass by 2035%, and the use of carbon fibers can lower the vehicle mass by 4065% 1-2. Polymer matrix in a composite is primarily to provide support for reinforcement fibers and add additional functional abilities. Polymer matrix can be either thermoset or
37、 thermoplastic. Thermosetting polymers are chemically cross-linked structures and do not melt upon reheating, and therefore they exhibit low viscosity, high stiffness, and excellent thermal resistance. Commonly used thermosets include epoxy and polyamide thermoplastic polymers involve no chemical re
38、actions during processing. The materials are formed through a purely physical process of heating and cooling. Thermoplastic polymers have the advantages of good fracture toughness and impact resistance and are ideal for producing parts of complex geometry and shapes. Commonly used thermoplastics inc
39、lude nylons, poly-ether-ether-ketone, and polyethylene. One of the most important factors affecting the properties of the composites is the relative proportion of the reinforcing fibers in the matrix, the so-called fiber volume fraction (Figure 1.2a). The volume fraction is exclusively used in the d
40、esign and analysis of composite structures and is often calculated from the fiber weight fraction, which can be readily obtained from the experimental measurement. Composites with higher fiber volume fraction often result in higher stiffness, but at higher cost. A lamina, or ply, is a plane layer th
41、at serves as the most fundamental architectural element in the construction of a laminate composite. The lamina can be in the form of either unidirectional fibers or woven fibers (Figure 1.2b). Unidirectional lamina has straight parallel fibers and thus Figure 1.1 Performance map of structural mater
42、ials. Shaded area indicates the area of metals.ix exhibits high stiffness and high strength. Woven fiber composites generally have high interlaminar strength and thus are not susceptible to delamination. A laminate composite is made up of multiple laminae or plies stacked together at various orienta
43、tions (Figure 1.2c). The laminae can be of various thicknesses or even different materials. The order in which laminae of various orientations are stacked together, one on top of the other, is called the stacking sequence. For example, the composites shown in Figure 1.2c are eight-layer laminate wit
44、h different stacking sequences: 08 and 0/90/452s. Based upon the stacking sequence, the composites can be classified into different categories, including symmetric laminates, balanced laminates, symmetric/balanced laminates, Figure 1.2 (a) Laminae with different fiber volume fractions, (b) Laminae w
45、ith different fiber configurations: unidirectional and woven (Daniel and Ishai, 2006) (used by permission, Oxford University Press, USA), and (c) Laminate with different stacking sequences. and anti-symmetric laminates. The proper design of a stacking sequence in a composite has significant impact o
46、n its strength and deformation mechanism. For example, a composite with a symmetric layup would eliminate the coupling stiffness between the layers and therefore minimize the warpage during heating and cooling. Compared to most traditional materials that generally possess monotonic properties, compo
47、site materials can be multifunctional (mechanical, thermal, electrical, magnetic, and so forth). Composites with multifunctional properties can be achieved by adding new functional components into the polymer matrix. For example, blending piezoelectric particles into the matrix can make composites e
48、lectrical x Figure 1.3 Hybrid or multifunctional composites: (a) carbon fiber composites with PZT particles and (b) carbon fiber composites with coated CNTs. conductive, while coating carbon fibers with carbon nanotubes (fuzzy fibers) can provide composites with sensing abilities (Figure 1.3). Desig
49、n Process of Composite Structures Traditionally, the automotive sector has designed structural components by using isotropic materials such as steels, aluminums, and plastics. The basic material properties necessary to the design of a homogeneous structure are Youngs modulus (E), Poissons ratio (), and failure strength (f). These properties for common materials, such as steel and aluminum, are readily available in materials handbooks and online resources (such as M). Therefore, the overall design process of a structural component made of
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