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Materials Science and Nanotechnology | Volume: 03
WORLD CONGRESS ON SMART MATERIALS AND STRUCTURES
&
3
rd
International Conference on
POLYMER CHEMISTRY AND MATERIALS ENGINEERING
November 21-22, 2019 | Singapore
Joint event on
U
ltrasonic motors have been adopted in high precision
applications such as in the robotics, automotive
industry, medical devices and autofocus of camera lenses.
They are characterized by compact size, low speed with
high torque and zero backlash. Since the shear piezoelectric
coupling factor and the shear piezoelectric constant are
higher than for the other piezoelectric effects, a relative
higher torque and a better efficiency are also attained.
Special attention is paid to the kinematics and the
geometry of the motor parts and to characteristics that
influence efficiency and torque. The stator is of disc-type,
made of piezoceramics and radially polarized. It is modelled
as an annular Reissner-Mindlin plate with piezoelectric
terms. Rayleigh-Ritz discretization is used to obtain
eigenfrequencies and eigenmodes of the stator plate. In
the laboratory, measured eigenfrequencies of the free
vibrations of the plate corroborate the numerical method.
Particularly, the generation of travelling waves requests
the excitation of two degenerated vibration modes. This
requires a specific electrode configuration.
A suitable vibration mode is chosen, so that the energy
losses through friction in the radial direction are minimized.
The transmission of load from stator to rotor occurs
through a ring of teeth over the stator. The kinetic energy
of the teeth set is formulated and taken into account in
the equations of motion. Additionally, the conditions for
the symmetry of the stator are stated with respect to the
disposition and the number of teeth. In the contact model,
point contact with a rigid rotor is assumed.
The present model, which is characterized by a few degrees
of freedom, is able to deliver relevant characteristics of
the motor. Performance parameters (at steady state) can
be calculated. It allows a systematical optimization of the
motor with respect to its geometry, its size, the number
and disposition of the teeth, and the electric excitation.
Biography
AnaCostaConradohascompletedherPhDfromtheTechnischeUniversität
Darmstadt and worked in the industry. She returned to academia as
master student. Currently, she is working as a research software engineer
at the University of Oslo and teaches programming for researchers.
e:
ana.conrado@protonmail.comAna Costa Conrado
University of Oslo, Norway
A piezoelectric travelling wave ultrasonic motor based on the shear effect
Mater Sci Nanotechnol, Volume: 03