Page 315 - Mechanics of Microelectromechanical Systems
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302 Chapter 5
Figure 5.37 Input and output displacements for a sagittal displacement amplification
microdevice: (a) quarter model; (b) full model
Example 5.17
Express the input and output stiffnesses, as well as the displacement
amplification of the microdevice with four curved flexure hinges sketched in
Fig. 5.27. The quarter-model of this sagittal microdevice, together with the
defining geometry, are shown in Fig. 5.38.
Figure 5.38 Quarter-model of displacement-amplification microdevice with four curved
flexure hinges
Solution:
The curvature radius of the flexure is R and the corresponding center
angle (not indicated in Fig. 5.38) is The lengths of the two adjoining rigid
links are and respectively. The input stiffness, output stiffness and
displacement amplification are calculated in a manner similar to the one used
for the straight-flexure quarter-model analyzed previously.
The reaction moment which is set when the force F acts at point 1,
can be found by considering that the rotation at point 2 is zero (the circular
flexure remains rigidly connected to the link 1-2 at that point). It is
considered that the local frame indicated in Fig. 1.20 of Chapter 1, it is also