Date: May 22, 2009 (Friday) Time: 1:00 p.m. - 2:00 p.m. Room: MME Conference Room (EC 3327)

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DEPARTMENT OF MECHAN
ICAL AND MATERIALS E
NGINEERING

MULTIDISCIPLINARY AN
ALYSIS, INVERSE DESI
GN, ROBUST OPTIMIZAT
ION AND
CONTROL (MAIDROC) LA
BORATORY

Presents an invited lecture on


Finite Element Design of Vibration Protective Pads for
Porta
ble Cryogenically Cooled Infrared Imagers


Michel M
.

Azoulay

Loughborough University, Loughborough, Leicestershire , LE11 3TU
, UK


Date:

May

22
, 2009

(Friday
)

Time:

1:00 p.m.
-

2:00

p.m.

Roo
m:

MME Conference Room (EC 3327)


Design of
novel, portable

and au
rally undetectable cryogenically cooled infrared imagers
often relies on compliant vibration protective pads for mounting the integrated dewar
-
detector
-
cooler assembly upon the imager’s enclosure. Extensive analytical study and
experimental effort have sho
wn that for the best acoustic performance the visco
-
elastic
properties of such pads need to be matched with the dynamic properties of the typically
undamped enclosure, subjected to the tight limitations imposed on the low frequency
cooler
-
induced line of s
ight jitter resulting f
rom the oscillations of the gas
dynamic torque
and compliance of the above pads.

Unfortunately, the regular approach to a design of the optimal vibration protective pad
does not seem to exist. As a result, the
development of

the suit
able vibration protective
pad is widely regarded
as a purely empirical process

and requires a great deal of
experimental trial
-
and
-
error effort.

The authors are attempting to apply the
regular
finite element modeling approaches to an
optimal design of suc
h vibration protective pads. In doing so, they are making use of the
full finite elements models of infrared imager enclosure with vibration mounted
integrated dewar
-
detector
-
cooler assembly. The optimal geometry and dynamic
properties of a compliant layer

of vibration protective pad are evaluated using the
optimisation procedure with purpose of attenuation the volume velocity of the active
radiating surface. The theoretical findings are in fair agreement with the outcomes of the
full
-
scale experimentation.




For further information and/or to schedule a p
ersonal meeting with the invited speaker
,

please contact Prof. G.S.
Dulikravich at (305) 348
-
7016 or e
-
mail to dulikrav@fiu.edu.