上海交通大学：《合成材料 Composite Materials》课程教学资源（讲义，2/2）

Composite Materials LIU Jing

Composite Materials LIU Jing

Reinforcement The mechanical properties of composites are a function of the type,shape and dimensions of the reinforcement. One of the dimensions of the reinforcement is usually small, a few microns,and the geometry of the reinforcement is one of the major factors in determining its effectiveness. Reinforcements may be fibrous,particulate or laminar

Reinforcement • The mechanical properties of composites are a function of the type, shape and dimensions of the reinforcement. • One of the dimensions of the reinforcement is usually small, a few microns, and the geometry of the reinforcement is one of the major factors in determining its effectiveness. • Reinforcements may be fibrous, particulate or laminar

Fibrous Reinforcement A fibrous reinforcement is characterized by its length (larger than 100 um)being much greater than its cross-sectional diameter, however the ratio of length to cross sectional area (aspect ratio) can vary widely (larger than 10). Fibers can be amorphous,polycrystalline,or single crystalline. 0 Long fibers with high aspect ratios give rise to continuous fiber reinforced composites. Discontinuous fiber composites care made using short fibers of low aspect ratio,which can be arranged in a random or ordered manner

Fibrous Reinforcement • A fibrous reinforcement is characterized by its length (larger than 100 μm) being much greater than its cross-sectional diameter, however the ratio of length to cross sectional area (aspect ratio) can vary widely (larger than 10). • Fibers can be amorphous, polycrystalline, or single crystalline. • Long fibers with high aspect ratios give rise to continuous fiber reinforced composites. • Discontinuous fiber composites care made using short fibers of low aspect ratio, which can be arranged in a random or ordered manner

Fibrous Reinforcement Continuous fiber reinforced polymer matrix composite

Fibrous Reinforcement Continuous fiber reinforced polymer matrix composite

Fibrous Reinforcement Whiskers are elongated single crystalline particles with diameter usually less than 1 um and aspect ratios that can be as low as 10. Owing to the very small dimensions and single crystalline nature,whiskers possess a high degree of structural and chemical perfection which give them an extremely high strength,elastic modulus and elongation at break. Because of the low aspect ratios,whiskers are not as effective as continuous fibers as reinforcing agents

Fibrous Reinforcement • Whiskers are elongated single crystalline particles with diameter usually less than 1 μm and aspect ratios that can be as low as 10. • Owing to the very small dimensions and single crystalline nature, whiskers possess a high degree of structural and chemical perfection which give them an extremely high strength, elastic modulus and elongation at break. • Because of the low aspect ratios, whiskers are not as effective as continuous fibers as reinforcing agents

Fibrous Reinforcement Typical structure of whiskers

Fibrous Reinforcement Typical structure of whiskers

Particulate Reinforcement Particulate reinforcements have dimensions which are approximately equal in all directions and may be spherical, cubic,platelets or any irregular geometry. Usually the orientation of the particles is random

Particulate Reinforcement • Particulate reinforcements have dimensions which are approximately equal in all directions and may be spherical, cubic, platelets or any irregular geometry. • Usually the orientation of the particles is random

Particulate Reinforcement X188 100Mm 0088 13 35 SEI Particulate SiC used for aluminum matrix composite

Particulate Reinforcement Particulate SiC used for aluminum matrix composite

Particulate Reinforcement Particulate reinforced aluminum matrix composite

Particulate Reinforcement Particulate reinforced aluminum matrix composite

(a) (b) (c) (d) Types of reinforcement for composite materials

Types of reinforcement for composite materials