Much confusion revolves around linear and non-linear numbers. The following outlines the mathematical process to convert from a number expressed in dB to a linear quantity. How do we convert to decibels and back again? Contine reading
What type of accelerometer should I use? What are the advantages/disadvantages of a charge mode accelerometer, an IEPE accelerometer and a bridge based accelerometer?
There are so many types of accelerometer that is often difficult to know what type of accelerometer to use. An IEPE accelerometer will have a high pass filter at about 5Hz. The charge type will, by it’s nature have what is effectively a high pass filter at about 0.1Hz. Therefore neither type will show DC levels. The charge type will usually have a lower frequency bandwidth than the IEPE type. Charge accelerometers can be used at higher temperatures however. Contine reading
There are a number of ways to find the natural frequency (resonance) of a part like an automotive inlet manifold. Here are three different types of popular test technique. But which one should you use and why? Contine reading
We were asked the following question…
I want to perform some cylinder head and inlet manifold vibration analysis, what should I do?
First we need to consider sensor selection Contine reading
Here we look at how to calibrate an accelerometer using a Prosig P5000 system.
Put the wax on the shaker top. Place the accelerometer in the axis you wish to calibrate with positive up and cable connected to P5000 with the relevant transducer class chosen.
Go to Single Channel Calibration screen.
Click on the Tone tab.
With P5000 armed turn on the shaker and monitor the sine wave on the real-time monitor and check Signal Quality as being GOOD.
With a GOOD sine wave click the Calculate button. It is recommended to click Calculate three times.
Check to see the Sensitivity change from what was originally entered when setting up the channel transducer information to the new calculated value. The calculated value should be close to the original.
DC Cal Offset is for DC level accelerometers.
Requested Excitation is for non IEPE (ICP) accelerometers such as capacitive.
After calculating the new sensitivity click on the Use button to make the change in the Transducer Sensitivity Acquisition Setup file.
NOTE: To achieve a GOOD signal reading place the shaker on a flat surface and avoid touching during operation. Make sure the surface the shaker is sitting on does not come in contact with other sources of vibrations or electrical conductance.
“How do I balance a shaft?” seems like a fairly straightforward question, but there are a number of things that we need to understand first. Here we look at a number of key concepts that need to be understood in order perform balancing.
What does balance mean?
Well broadly speaking to balance a shaft, mass must be added or removed at certain angles. The concept being that the centre of gravity and rotational centre of the shaft will be equal when the shaft is balanced. Contine reading
After listening to customer feedback, we have completely re-engineered the DATS Hammer Impact software. The new version will ship with the next DATS update (not the soon-to-be-released V7.0.23). In the meantime you will be able to download and preview the new package. You will of course need a P8000 system and a DATS licence with the Hammer Impact option enabled. Contine reading
A user has three signals captured using a triaxial accelerometer and asked “What is the simplest way to get the XYZ resultant from run-up file?” He had tried forming a resultant of the raw time histories, but didn’t fully understand the resultant time history.
Of course, the correct way of processing the data is to calculate the individual waterfalls from the x, y & z data and then calculate a resultant waterfall. Contine reading
How do you measure the causes of a noise or vibration with respect to several sources? Which source is causing what part of the response?
For example, how does the noise inside the cabin of a vehicle relate to the engine noise or wheel hub noise and vibration? Contine reading
Generally when developing and testing bearings a simple step by step procedure should be followed.