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INTL-SENSOR > Supply > Filtered,Triaxial,ICP®AccelerometersforPowertrainNVHApplications

Filtered,Triaxial,ICP®AccelerometersforPowertrainNVHApplications

http://www.intl-sensor.com Time:2010/8/26 14:13:59 Count : 2690 Times

Filtered,Triaxial,ICP®AccelerometersforPowertrainNVHApplications

High frequency, metal-to-metal impacts are common during the combustion events of

today’s powertrain. These impacts can excite the high frequency resonance of the

piezoelectric crystal in any accelerometer (PCB® or otherwise) to saturate the signal and

cause clipping in the contained ICP® signal conditioning ampliﬁer. Any system,

once driven nonlinear, will produce spurious frequencies at, above, and below the

frequencies contained in its input stimulus. If not recognized, this frequency production

results in erroneous test data when it extends into the frequency range of interest. To help

alleviate this event, PCB® offers low pass ﬁltering in select triaxial accelerom-

eters which suppresses the effects of any crystal resonance before they can enter and

over range the ICP® signal conditioning ampliﬁer. This preﬁltering minimizes the op-

portunity for erroneous frequency content to be generated and accepted as valid data.

This ﬁltering, however, causes slight phase shifts in the higher frequency data. If

phase is important in your analysis (e.g. operating mode shapes, transfer path analysis,

vibroacoustics, etc.) then a single reference channel can be used to extract correct

phase in post processing routines. A more automated solution may be possible with

some of the data acquisition units. Contact PCB® for additional information.

In addition to ﬁltering, PCB® Series 339A Triaxial ICP® accelerometers are designed

with a temperature coefﬁcient of less than 0.0125% / °F (0.02% / °C), which allows

for precision amplitude data for test applications with large thermal shifts such as

powertrain vibration testing, powertrain NVH, certain vehicle systems NVH tests, road

load data acquisition, and durability testing in climatic chambers.