Mechanical Impedance Sensor Model 288A11

Mechanical Impedance 

Sensor Model 288A11

Low mass sensor amplifiers for impedance measurement on small structures.

1. with built-in microelectronic.
2. weighs only 45 grams.
3. high sensitivity : force 1000 mv/Ib motion 100 mv/g.
4. measures over wide frequency range.
5. features low dynamic mass.

Combination force transducer and accelerometer measures both force and motion in testing the transactional behavior of interacting mechanical structures, with sinusoidal or random force generators (vibrators).

Model 288A11 Mechanical impedance Sensor functions to transfer both the stimulus (force) and response (motion) into electrical signals, This combined instrument senses force and motion at the driving point where the stimulus (oscillating force) is applied to the test object.

Model 288A11 is structured with proven, rigid, quartz stress-gage elements and microelectronic line driver amplifiers.

Thin quartz disks or plates in both the force and motion sensors behave as stress gages operating in thickness-compression modes. power units with gain (Model 480D06) shown in the typical system below are recommended to take full advantage of the wide dynamic measuring range of these instruments. 

Behavior of the test object is affected somewhat by the effective mass (end piece of the force sensor. Some FFT analyzers employ automatic mass compensation to correct for this effect. The accelerometer in this instrument senses the acceleration aspect of motion, which is usually integrated into a velocity signal (v) to compute mechanical impedance (F/V). Model 48oAo8 Integrating power unit provides this integration over a frequency range from 10 Hz to 5000 Hz. Frequently there is a time delay as well as an amplitude difference between the stimulus (force) and response (motion) signals, which when mathematically modeled is referred to as phase shift. 

Because the force and motion are measured at the same Point, any phase shift detected can be attributed directly to the test object.