Page 305 - Mechanics of Microelectromechanical Systems
P. 305
292 Chapter 5
The amplifications of the two mechanisms are calculated by means of the
corresponding equations, and a comparison between the two amplifications is
performed through the two device’s amplification ratio, as shown in Fig. 5.24.
The amplification of the mechanism in Fig. 5.21 (a) is larger than the one
produced by the mechanism in Fig. 5.21 (b) for the set of numerical values of
this problem, as shown in Fig. 5.24.
Example 5.14
The microdevice of Fig. 5.25 is actuated linearly by a thermal actuator of
length Determine the horizontal displacement at the free tip 1 of the rigid
vertical link for a temperature increase Known are all geometrical
amounts as well the elastic and thermal properties.
Figure 5.25 Thermally-actuated displacement-amplification microdevice
Solution:
The horizontal displacement at point 2 is given in Eq. (5.68) as a
function of the horizontal displacement at point 3 and the slope at the same
point. As shown previously for the mechanism of Fig. 5.21 (a), the
displacement and rotation can be calculated as:
where is the force generated by thermal actuation at the interface between
the horizontal actuator and the vertical rigid link. The value of is given in
Eq. (4.7), Chapter 4 and is rewritten here for convenience:
