ONOSOKKI DS-2000 series Operation Manual
Measurement of frequency response function
Hide thumbs
Also See for DS-2000 series:
- Manual (16 pages) ,
- Operation manual (20 pages) ,
- Operation manual (23 pages)
Advertisement
Quick Links
Advertisement
Related Manuals for ONOSOKKI DS-2000 series
Summary of Contents for ONOSOKKI DS-2000 series
- Page 1 DS-2000 Series Measurement of Frequency Response Function ONO SOKKI CO., LTD.
- Page 2 Contents 1. Flow Chart to Measurement 2. Device Connections 3. DS-2000 Setup 4. Measurement 1. Flow Chart to Measurement The following explains procedures for measuring the frequency response function using an impulse hammer. Connect an Connect accelerometer and accelerometer and an impulse hammer.
- Page 3 2. Device Connections Connect an "accelerometer" and an "impulse hammer" to the DS-2000. Although the acceleration sensor comes in two types, built-in amplifier type and charge output type, the use of the built-in amplifier type is assumed here. Connect each sensor with the DS-2000 series as shown below.
- Page 4 3. DS-2000 Setup Preparing for Setup To correctly operate the connected impulse hammer and accelerometer and display data, set operating conditions and sensitivity of the sensor to an FFT analyzer. Sensitivity and operating condition settings are described in the "Calibration Chart" supplied with the accelerometer to be used.
- Page 5 ② Drive current indicates that a current of 2.4mA is sent to the sensor. In the documents supplied with the "GK-3100" impulse hammer, necessary data are described as follows: The hammer is provided with an Plastic and vinyl extender (weight for weight tips are used.
- Page 6 Input Source Setup Set sensitivity, operating conditions, etc. of the sensor connected to the DS-2000. Here, procedures will be explained on the premise that CH1 is used for impulse hammer and CH2 for accelerometer. Click the Input menu and then select Voltage Range. (1) For both channels, uncheck the [AUTO] check box.
- Page 7 Unit Conversion It is inconvenient that the vibration waveform is still displayed as a voltage. Use the unit calibration function to allow direct read from voltage to acceleration. Click the Input menu and then select Unit / Calibration to open the dialog. Input hammer vibration force unit N (newton).
- Page 8 Display Selection Setup in screen At the time of data measurement, specify the top for time waveform display of CH1 and the bottom for time waveform of CH2. Screen setup Select a channel and a function to be displayed from the setup drop-down lists. Select channel.
- Page 9 Adjusting Voltage Range Set a voltage range and a frequency range to a value suitable for measurement. While hammering the object under measurement (with a constant force) as if it drops by its weight, select a range for displaying a signal waveform as large as possible so that the LED of the LEVEL indicator for each channel does not light up.
- Page 10 Applying Trigger Stop a waveform at a desired position in the screen using the trigger function to make it easier to observe the waveform. Click the Input menu to open the Trigger Set. Apply trigger to the waveform of CH1 (impulse hammer) while hammering the object under measurement.
- Page 11 Press the TRIG button in the screen to set to the trigger-ready state. Waveform of impulse hammer Waveform of accelerometer When you hammer the object under measurement and then the waveform stops at a specified position, trigger is OK.
- Page 12 Window Setup Since the signal of the impulse hammer is a single-shot impact signal, select the rectangular window without compensation. Click the Input menu and then select Time Window. Then, make setting for each channel. Select [Rect] to every channels.
- Page 13 Determining Frequency Range Determine a frequency range based on the following: Select it within the analysis frequency range of the sensor (accelerometer) Select it from the frequency resolution to be focused (The lower the frequency range, the higher the frequency resolution becomes.) ...
- Page 14 AD Over Cancel Setup This function eliminates data if voltage of an input signal exceeds a limit because of excessive hammering. Click the Input menu and then select Sampling condition. Check A/D OverCancel. *Please check whether the trigger is applied before turning on the A/D over cancel.
- Page 15 3-10 Average Setup To minimize a measurement error, data is averaged. In this case, summation averaging of spectrum is used. (This setting is selected as initial setup. If changed, setup is required.) The standard number of averaging is 4 or 8. Click the Input menu and then select Average. Select Power Sum (Spectrum Summation).
- Page 16 4 Measurement Performing Averaging and Starting measurement Perform averaging and start measurement. Press AVG. * Make sure that TRIG is ON. When you press the switch and a signal is input, averaging starts automatically. Start hammering. When the signal (hammering) is input for the specified number of averaging, averaging stops automatically.
- Page 17 Checking Frequency Response Function Data under Observation Here, check data by displaying the frequency response function at the top and the coherence function at the bottom. * The coherence function represents the correlation between input and output signals. Coherence becomes worse if noise is mixed between input and output or if rattling or other nonlinear factor is present.