Subject 6 Mechanical properties & more homework questions

Subject 6 Mechanical properties & more homework questions

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Unformatted text preview: The effects of small sizes and (internal) nanostructures Subject 6 Subject 6 Mechanical Properties Mechanical Properties Small Small-- scale structures and materials scale structures and materials Nanowires and nanotubes MEMS, NEMS components (beam, chain, gear, spring..) Nanocrystalline films and lines Mechanical properties important for their integrity and functions Unusual mechanical behavior of interest to basic science Example of property measurement for small object: Example of property measurement for small object: AFM three AFM three-point bending test point bending test d t d c d n Cantilever d n Laser beam Laser diode Mirror Position sensitive photodetector A B C D Sensor output (displacement & force) (x, y) stage Piezoelectric scanner z Z stage Feedback amplifier Nanowire before bending Feedback loop ((x, y, z) position) after bending Tip Sample holder x y z d t d c d n Cantilever d n Laser beam Laser diode Mirror Position sensitive photodetector A B C D A B C D Sensor output (displacement & force) (x, y) stage Piezoelectric scanner z Z stage Feedback amplifier Nanowire before bending Feedback loop ((x, y, z) position) after bending Tip Sample holder x y z x y z Young's modulus, tensile strength and density of carbon nanotubes compared with some other materials Material E (GPa) Tensile (GPa) Density (g/cc) Single wall nanotube 1054 150 Multi wall nanotube 1200 150 2.6 Steel 208 0.4 7.8 Epoxy 3.5 0.005 1.25 Wood 16 0.008 0.6 Au Au nanowires nanowires a few nm in diameter a few nm in diameter Au Au nanowires nanowires : smaller is stronger : smaller is stronger Micro-compression test of FIB-fabricated micropillars Micro-compression test of Au pillars: Smaller is stronger Different from large Different from large-grained metals grained metals When internal layers and grains are small .. Nano...
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This note was uploaded on 03/30/2010 for the course EN 510.422 taught by Professor Dr.evanma during the Spring '10 term at Johns Hopkins.

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Subject 6 Mechanical properties & more homework questions

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