Project Title:

Adaptive Vibration Suppression Mount for Cryogenic Coolers

92-1-09.17-7351                                                   NAS05-32414
Adaptive Vibration Suppression Mount for
     Cryogenic Coolers
CSA Engineering, Inc.
2850 West Bayshore Road
Palo Alto, CA  94303-3843
Eric M. Austin                                       (415-494-7351)

Abstract:

     Cryocoolers produce vibration levels that cause unacceptable
jitter of infrared sensors. This movement leads to reduced
performance because of increased line-of-sight jitter. These
harmful forces, should, therefore, be suppressed before they reach
sensitive components. The traditional method, passive isolation,
relies on soft mounts between the disturbance machinery and the
structure. However, isolators have low mount stiffness which leads
to problems such as static misalignment, increased travel
requirements, and decreased mount strength. This project will
develop an innovative mounting system for cryocoolers--
specifically, mounts with adaptively-tuned dynamic compliance
characteristics and high static stiffness. Using a combination of
piezoceramics and passive isolators, the hardmounts will be
designed to be stiff at all frequencies except the discrete
disturbance frequencies of the cryocooler at which point the
mounts will be soft. This system will effectively isolate the
structure from the disturbances without the problems that
traditional isolators cause. The Phase II "adaptive hardmount"
will be able to track changes in the disturbance frequencies and
adjust the "notches" in the stiffness to follow these changes. The
adaptive hardmount will be lightweight, have no moving parts, and
will require very little power to operate.

Potential Commercial Application:

Potential Commercial Applications:  The "adaptive hardmount" will
solve many vibration isolation problems that cannot be solved with
available techniques. Near-term commercial markets are likely to
be found in performance-driven applications: machinery such as
cryocoolers and control moment gyros in spacecraft; machinery for
submarines, torpedoes and other naval vessels; turbines and
gearboxes in aircraft and helicopters; and equipment for making
computer chips.

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