BRUEL & KJAER 2305 - Strain Gage Measurement Recording

Damping Factor Measurement by Reverberation Decay Method. Another
method of determining the damping factor is to record the reverberation
decay curve of the sample. This can be made by means of the same instru-
mentation. In this case, however, the Beat Frequency Oscillator Is adjusted
to the exact frequency at which it is desired to measure the damping factor,
and the pressbutton marked "Oscillator Stop" is pressed. The decay of the
vibrations is then recorded on the Level Recorder and the damping factor
calculated from the resultant reverberation time. This method is advantage-
ous when measurements are made on materials with very small damping
factors. The inherent losses in the measuring set-up limits the smallesf
measurable damping factors and are equivalent to a damping factor smallel
than 0. 00!.
Additional Briiel & Kjrer literature: Technical Review, No. 4-1957 and
1-1958.
Recording of Strain Gage Measurements.
In strain gage measurements it is often a necessity to register the results,
especially when dynamic or multi-point measurements are carried out.
When employing the B & K strain gage equipment, static, quasi-static,
dynamic and also multi-point measurements can be carried out and recorded
by the Level Recorder.
Additional Briiel & Kjrer literature: Technical Review, No. 1-1957, 3-1959
and 2-1956.
Recording of Static, Quasi-Static and Low-Frequency Dynamic
Measurements.
By combining the B & K Strain Gage Apparatus Type 1516 with the Level
Hecorder as shown in Fig. 6.53 an equipment for recording static and low-
frequency dynamic phenomena is gained. The Strain Gage Apparatus which
utilizes all types of resistive strain gages (10-1000 Q) has a sensitivity (full
deflection) from 25 f'Strain to 30000 f'Strain and covers a dynamic range
of 0-300 Hz (c Is) and 20 Hz (cIs) - 100 kHz (kc/s) .
For the carrying out of strain gage measurements a linear scale reading is
required thus the 10-35 mV Range Potentiometer (ZR 0001) should be
inserted in the Level Recorder, and it is recommended to use either of the
recording papar types QP 0102 or QP 0402 (50 mm width) or the subsidiary
QP 1102 (100 mm width).
As an example Fig. 6 .5 4 is reproduced to show the recording of dynamic strain
in the connecting rod on a one-cylinder four-stroke combustion engine unde '
working conditions.
Recording of the instantaneous amplitude of signals with frequencies up to
approx. 5 Hz (c/s) is possible for sine waves, when the whole width of the
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