Page 293 - Mechanics of Microelectromechanical Systems
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280 Chapter 5
Figure 5.14 Bent beam thermal actuator: (a) microdevice with force beam; (b) equivalent
actuation model with springs
As a consequence, the force exerted on the beam by the thermal actuator is:
By substituting (from Chapters 4 and 3, as mentioned) and of Eq.
(5.41) into Eq. (5.40), the unknown Young’s modulus is E = 347 GPa and the
force on the beam is according to Eq. (5.42).
Example 5.9
Determine the displacement of the linear micromotor sketched in Fig.
5.15. The actuation is provided by two identical two-beam units (as described
in Fig. 4.14, Chapter 4) and additional suspension is added into the system by
the two end beams. The beams and the compliant parts of the actuators have
identical cross-sections Known is the geometry of the
microsystem as well as
the material properties (E = 150 GPa, and the temperature
increase
Solution:
This example is conceptually similar to the previous one, in the sense
that two actuators are placed in parallel to increase the amount of horizontal
force and to produce a horizontal motion, because of the symmetry. As a
result of this similitude, the equation of static equilibrium between the
actuation force and the elastic restoring forces of the two beams is:
