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Compression of microspheres: Theory and application

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Hardness<br />

Abbott & Firestone:<br />

Contact area & 2<br />

Hardness / &<br />

& 2.8 0.1 <br />

• Simplification <strong>of</strong> contact mechanics<br />

• No volume conservation<br />

• Discontinuities at yield point<br />

• Fixed relation <strong>of</strong> yield strength <strong>and</strong> hardness<br />

• Conservative<br />

CEB:<br />

Contact area 2 <br />

Hardness / <br />

( 0.454 0.41)<br />

5.3 0.2 <br />

• Volume conservation<br />

• Small plastic deformation<br />

• Discontinuities at yield point<br />

• Fixed relation <strong>of</strong> yield strength <strong>and</strong> hardness<br />

in fully plastic regime<br />

Force [µN]<br />

J. Paul PiKo-Workshop Siegen 2012<br />

Count<br />

800<br />

600<br />

400<br />

200<br />

20<br />

16<br />

12<br />

0.00 0.21 0.42 0.63 0.84<br />

0<br />

0 100 200 300 400<br />

8<br />

4<br />

SiO 2<br />

(R = 250nm)<br />

yield point<br />

Rel. deformation<br />

Hertz<br />

A&F/CEB<br />

Deformation [nm]<br />

Abbott&Firestone<br />

SiO 2<br />

(R = 250nm)<br />

0<br />

2 3 4 5 6<br />

Hardness [GPa]<br />

CEB<br />

8

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