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  • - Mechanics is the study of forces and their effects on bodies at rest or in motion. - MECHANICS - FLUID MECHANICS - FLUID STATICS (hydrostatics) - FLUID DYNAMICS (hydrodynamics) - SOLID MECHANICS - STATICS - DYNAMICS - Statics is a discipline in the field of mechanics in which we study the effects of forces on solid bodies at rest. We assume these solid bodies are rigid , that is they do not deform (stretch, compress, bend, flex or twist).
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    1. 1. <ul><li>Composites </li></ul>
    2. 2. Learning Objectives: <ul><li>What are composites made of? </li></ul><ul><li>How are composites fabricated? </li></ul><ul><li>Composite Material Properties </li></ul>
    3. 11. <ul><li>Examples of Composite Members: </li></ul><ul><li>Concrete slab reinforced with steel </li></ul><ul><li>Carbon fiber and plastic snow skis </li></ul><ul><li>Kevlar and fiberglass boats </li></ul><ul><li>Concrete slab on a metal deck </li></ul><ul><li>. </li></ul>Introduction concrete corrugated metal deck
    4. 12. Introduction <ul><ul><li>Composite materials consist of two components: the fiber and the matrix </li></ul></ul><ul><ul><li>Fiber – the load carrying material </li></ul></ul><ul><ul><li>Matrix - the fluid binder that hold the fibers in place when it solidifies. </li></ul></ul>
    5. 13. Fibers Materials: <ul><ul><li>Glass fiber (hence, fiberglass) </li></ul></ul><ul><ul><li>Aramid fiber (Kevlar) </li></ul></ul><ul><ul><li>Graphite fiber (carbon) </li></ul></ul><ul><ul><li>Metal fiber (concrete, ceramics) </li></ul></ul><ul><ul><li>Boron fiber </li></ul></ul><ul><ul><li>Wood fiber </li></ul></ul>
    6. 14. Fibers Forms: <ul><ul><li>Strands (roving) – typically used with mandrel . Direction and spacing controlled </li></ul></ul><ul><ul><li>Woven mesh in sheets. Direction controlled </li></ul></ul><ul><ul><li>Chopped fiber (approx 1” long) – random direction </li></ul></ul>
    7. 16. Back to airplane wing
    8. 17. <ul><li>Stresses in Beams </li></ul><ul><li>A.) Bending Stresses </li></ul><ul><li>1.) Introduction </li></ul><ul><li>When a beam is subjected to positive bending moment, the top shortens and the bottom lengthens. </li></ul>
    9. 18. <ul><li>The bending strains are zero at the neutral axis. </li></ul><ul><li>The bending strains increase proportionately with the distance from the neutral axis. </li></ul><ul><li> The maximum strains occur at the top and bottom of the beam (outer fibers) </li></ul>
    10. 19. <ul><li>Since stress is directly related to strain </li></ul><ul><li> =  E), bending stress is also zero at the neutral axis and increases with the distance from the neutral axis. </li></ul><ul><li>The maximum bending stresses occur at the top and bottom of the beam (outer fibers) </li></ul>
    11. 20. <ul><li>2.) Maximum Bending Stress </li></ul><ul><li> b,max = Mc </li></ul><ul><li> I </li></ul><ul><li> b,max = Maximum bending stress at a given cross-section (ksi). </li></ul><ul><li>c = Distance from N.A. to the outer fibers of cross-section (in) </li></ul><ul><li>M, I = as defined before. </li></ul>N.A. c top c bot y
    12. 21. <ul><li>3.) Strong Axis vs. Weak Axis </li></ul>Strong Axis N.A. Weak Axis
    13. 22. <ul><li>B.) Shear Stress - Average Web Shear </li></ul><ul><li> v = V_ </li></ul><ul><li>dt w </li></ul>d t w d t w d t w

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