72
PRODUCTS & SERVICES
world’s smallest iepe
triaxial accelerometer
Size should be a crucial factor when selecting an accelerometer
// The Endevco 35C
accelerometer is small
enough to be used instead
of three accelerometers Who, on Heaven’s green earth, would
DECEMBER 2019 \\ AEROSPACETESTINGINTERNATIONAL.COM
PERFORMANCE
The 35C has an integral three-foot cable that
terminates to a single threaded ¼-28 4-pin
connector. This accelerometer is available in
three sensitivities: 2.5 mV/g, 5 mV/g and 10
mV/g. It operates in annular shear mode
which exhibits excellent output sensitivity
stability over time. The 35C is also designed
with a very low noise floor that results in an
outstanding signal to noise ratio for more
accurate measurements.
The accelerometer incorporates an internal
hybrid signal conditioner in a two-wire
system, which transmits its low impedance
voltage output through the same cable that
supplies the required constant current power.
Typical resonance frequency of the Model
35C is 40 kHz with maximum amplitude
response (±5%) of z and y axis of 2-8000 Hz
and maximum amplitude response (±5%) of x
axis of 2-6000 Hz. Highest nominal range is
±2800 g’s.
This accelerometer operates directly with
industry standard, easily available data
systems that have built-in constant current
power supply that provides low per channel
costs. Endevco also offers optional Models
123 and 133 signal conditioners for the 35C.
The 35C offers many benefits to aerospace
engineers whose end goal is keeping people
safe and the planet green. Its technology
requires little operator attention, training or
installation expertise. High quality data is
effortlessly acquired over extended distances
with minimal noise and electrical
interference. You could even heat up your
coffee to 125°C, pour it over the 35C and still
get good data without harming the device. \\
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want to buy a triaxial accelerometer,
much less one that’s so small it can
hardly be seen?
It’s a good question from a cost-conscious
test professional that sees the price of three
single axis accelerometers as less expensive
than a triaxial accelerometer and one who is
measuring vibration on large objects.
However, time is money and preparing a
single location for mounting one device
rather than three locations for three devices
makes sense.
Further, cable installation and connecting
to instrumentation is less complicated and
less time consuming for a single location
than three. From a measurement perspective,
taking data from a single location allows test
professionals to preserve phase information
as well as to ensure the data is not
contaminated by structural differences
among locations.
MINIATURE AND LIGHTWEIGHT
Size is important for two reasons. First, it
avoids mass-loading effects where the mass
of the accelerometer on a small structure
alters the natural frequency of the structure
under test. Secondly, many measurements
have very demanding space restrictions.
Consequently, the ultra-miniature, lightweight
footprint of Endevco’s 35C makes it ideal for
space-restricted testing applications,
especially in the aircraft, spacecraft, satellite,
and missile industries where more
conventional accelerometers cannot be used.
The 35C is an ultra-miniature, adhesive
mounted triaxial piezoelectric accelerometer
with integral electronics. Its tiny size, 0.235in
cube, and light weight, 0.76g (sensor only),
makes it ideal for measuring vibration on very
small objects.
All materials used for the Model 35C
construction have less than or equal to 1%
TML (Total Mass Loss) and a CVCM (Collected
Volatile Condensed Mass) less than or equal
to 0.1%, verified by NASA documentation. The
shear ferroelectric crystal technology
underlying the sensor design provides
very low sensitivity to base strain, cable
strain and very low thermal transient
response. This technology also provides a
wide-band frequency and insensitivity to
non-acceleration input in a rugged and
reliable package.
The 35C’s hermetically sealed titanium
case is well-suited for use in humid, corrosive
and dirty environments. Further, its
waterproof Ingress Protection Marking (IP68)
guarantees performance at 100 meters depth
and 48 hours duration. Mounting the
accelerometer is easily performed using
Cyanoacrylate adhesives while removal is
achieved with the appropriate solvent and
the removal tool supplied with
each accelerometer.
/AEROSPACETESTINGINTERNATIONAL.COM
/pati