Marc.Micromechanics

Marc.Micromechanics - Application of the Finite Element...

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Unformatted text preview: Application of the Finite Element Method Using MARC and Mentat 10-1 Chapter 10: Composite Micromechanics 10.1 Problem Statement and Objectives Given the micromechanical geometry and the material properties of each constituent, it is possible to estimate the effective composite material properties and the micromechanical stress/strain state of a composite material. The objectives of this project are (1) to determine the effective stiffness properties c E 1 , c E 2 , c 12 , c 23 of a unidirectional composite material and (2) to determine the strain concentration factor in the matrix region when the composite material is subjected to a uniform transverse normal strain in the X 2 direction. NOTE TO ME 424 CLASS: Only do Part (2). 10.2 Background A composite material is often defined as a combination of two or more materials fabricated in such a way that the individual constituents (materials) can still be readily identified in the final form. If designed properly, this combination of materials yields a composite material that exhibits the best properties of each constituent as well as some advantageous properties not exhibited by the individual constituents. One example of such a material is a unidirectional fiber reinforced composite, which is often used in aerospace structures. An idealized micromechanical view of a unidirectional fiber reinforced composite material is shown in Figure 10.1. In these materials, the fibers have a very small diameter and a very high length-to-diameter ratio. This geometry yields excellent stiffness and strength characteristics in the fiber, since the crystals tend to align along the fiber axis and there are fewer internal and surface defects than in the bulk material. The properties of commonly used fiber materials are given in Table 10.1. These fibers are embedded in another material, often called the matrix material. Matrix materials may be polymers, metals, or ceramics. Some common matrix material properties are given in Table 10.2. Application of the Finite Element Method Using MARC and Mentat 10-2 Figure 10.1 Idealized representation of a unidirectional fiber-reinforced material. X 1 (fiber direction) X 2 X 3 Application of the Finite Element Method Using MARC and Mentat 10-3 Table 10.1 Fiber and Wire Properties 1 Fiber or Wire Density, lb/in 3 (kN/m 3 ) Tensile Strength, S 10 3 lb/in 2 (GPa) S 10 5 in (km) Tensile Stiffness, E 10 6 lb/in 2 (GPa) E 10 7 in (10 6 m) Aluminum .097 (26.3) 90 (.62) 9 (24) 10.6 (73) 11 (2.8) Titanium .170 (46.1) 280 (1.9) 16 (41) 16.7 (115) 10 (2.5) Steel .282 (76.6) 600 (4.1) 21 (54) 30 (207) 11 (2.8) E-Glass .092 (25.0) 500 (3.4) 54 (136) 10.5 (72) 11 (2.8) S-Glass .090 (24.4) 700 (4.8) 78 (197) 12.5 (86) 14 (3.5) Carbon .051 (13.8) 250 (1.7) 49 (123) 27 (190) 53 (14) Beryllium .067 (18.2) 250 (1.7) 37 (93) 44 (300) 66 (16) Boron .093 (25.2) 500 (3.4) 54 (137) 60 (400) 66 (16) Graphite .051 (13.8) 250 (1.7) 49 (123) 37 (250) 72 (18) Table 10.2 Thermosetting Resin Matrix PropertiesTable 10....
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This note was uploaded on 07/25/2008 for the course ME 424 taught by Professor Averill during the Spring '05 term at Michigan State University.

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Marc.Micromechanics - Application of the Finite Element...

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