ES 1021-07 Science of Density and Stiffness.pdf - The...

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ES 1021 The Science behind Stiffness
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The Science behind Stiffness Atoms in crystals and glasses are linked by atomic bonds that behave like springs. Stretching or compressing the bond stores energy. The equilibrium atom separation is at the bottom of the energy well. Bond Type Examples Bond Stiffness [N/m] Young’s Modulus [GPa] Covalent Carbon-Carbon 50 180 200 1000 Metallic All metals 15 75 60 300 Ionic Sodium chloride 8 24 32 96 Hydrogen Polyethylene 3 6 2 12 Van der Waal’s Waxes 0.5 1 1 4
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