第五章 composites复合材料.docx

1、第五章 composites复合材料5 composites教学目的: Principle of combined action of composites, rule of mixture of composites; longitudinal strengths for discontinuous and aligned fibrous composite materials教学重点: Principle of combined action of composites, rule of mixture of composites教学难点: Longitudinal strengths f

2、or discontinuous and aligned fibrous composite materials教学方法: Multimedia学时分配5 composites (1)5.1 Introduction 15min5.2 Fiber Reinforced Composites 5.2.1 Structural composite 10min5.2.2 Particle and Fiber Reinforced Composites 20 min5 composites (2)5.3 Polymer-matrix composites 5.3.1 Glass fiber-reinf

3、orced polymer composites 20 min5.3.2 Carbon fiber-reinforced polymer composites 15 min5.3.3 Aramid fiber reinforced polymer composites 10 min5.4 Metal-matrix composites 45min5 composites (3)5.5 Ceramic-matrix composites 45min5.6 Carbon-matrix composites 45min教学过程与内容：5.1 IntroductionA composite, in t

4、he present context, is a multiphase material that is artificially made, as opposed to one that occurs or forms naturally. In addition, the constituent phases must be chemically dissimilar and separated by a distinct interface. Thus, most metallic alloys and many ceramics do not fit this definition b

5、ecause their multiple phases are formed as a consequence of natural phenomena. In designing composite materials, scientists and engineers have ingeniously combined various metals, ceramics, and polymers to produce a new generation of extraordinary materials. Most composites have been created to impr

6、ove combinations of mechanical characteristics such as stiffness, toughness, and ambient and high-temperature strength. Many composite materials are composed of just two phases; one is termed the matrix, which is continuous and surrounds the other phase, often called the dispersed phase. The propert

7、ies of composites are a function of the properties of the constituent phases, their relative amounts, and the geometry of the dispersed phase. Dispersed phase geometry in this context means the shape of the particles and the particle size, distribution, and orientation; these characteristics are rep

8、resented in Figure 5.1. extraordinary materials. Most composites have been created to improve combinations of mechanical characteristics such as stiffness, toughness, and ambient and high-temperature strength. Many composite materials are composed of just two phases; one is termed the matrix, which

9、is continuous and surrounds the other phase, often called the dispersed phase. The properties of composites are a function of the properties of the constituent phases, their relative amounts, and the geometry of the dispersed phase. Dispersed phase geometry in this context means the shape of the par

10、ticles and the particle size, distribution, and orientation; these characteristics are represented in Figure 15.1.Figure 5.1One simple scheme for the classification of composite materials is shown in Figure 5.2, which consists of three main divisionsparticle-reinforced, fiber-rein- forced, and struc

11、tural composites; also, at least two subdivisions exist for each. The dispersed phase for particle-reinforced composites is equiaxed (i.e., particle dimensions are approximately the same in all directions); for fiber-reinforced composites, the dispersed phase has the geometry of a fiber (i.e., a lar

12、ge length-todiameter ratio). Structural composites are combinations of composites and homogenous materials. The discussion of the remainder of this chapter will be organized according to this classification scheme.Figure5.25.2 Particle And Fiber Reinforced Composites5.2.1 structural compositeA struc

13、tural composite is normally composed of both homogeneous and composite materials, the properties of which depend not only on the properties of the constituent materials but also on the geometrical design of the various structural elements. Laminar composites and sandwich panels are two of the most c

14、ommon structural composites; only a relatively superficial examination is offered here for them.1 LAMINAR COMPOSITESA laminar composite is composed of two-dimensional sheets or panels that have a preferred high-strength direction such as is found in wood and continuous and aligned fiber-reinforced p

15、lastics. The layers are stacked and subsequently cemented together such that the orientation of the high-strength direction varies with each successive layer (Figure 5.3). For example, adjacent wood sheets in plywood are aligned with the grain direction at right angles to each other. Laminations may

16、 also be constructed using fabric material such as cotton, paper, or woven glass fibers embedded in a plastic matrix. Thus a laminar composite has relatively high strength in a number of directions in the two-dimensional plane; however, the strength in any given direction is, of course, lower than it would be if all the fibers were oriented in that direction. One example of a relatively complex laminated structure