[An Introduction To Vibration Analysis - Part 2] Introduction This post on vibration measurement techniques is the second in our series, introducing vibration analysis. Future posts will continue the exploration…
When using vibration data, especially in conjunction with modelling systems, the measured data is often needed as an acceleration, as a velocity and as a displacement. Sometimes different analysis groups require the measured signals in a different form. Clearly, it is impractical to measure all three at once even if we could. Physically it is nigh on impossible to put three different types of transducer in the same place.
An Impact Hammer double hit is viewed as a common problem, and most hammer impact testing software offers a "Double hit" rejection function. Signals captured with double impacts are not…
A Hammer Impact Test is also known as a Modal Test, Impulse Test, Tap Test, Bump Test or, simply, a Hammer Test. It is a method of testing that allows…
This article discusses quantifying basic vibration signals from three aspects: signal type, signal level, and signal display format. Mathematical expressions and typical applications are also introduced. A simple harmonic vibration…
As mentioned in our previous two articles, when performing experimental modal testing of a structure or component using impact (or ping) testing, it is important to consider and verify the…
Since DJB joined Condition Monitoring Technology Group (CMTG) in 2021 we have been able to bring new knowledge and capability to the group, especially when working alongside Prosig. We have…
The difference between Low noise and Non-Low noise accelerometer cables. It is important to use the correct cable when using accelerometers. A charge output accelerometer must be used with a…
Mass loading is the phenomenon whereby the mass of the Accelerometer alters the natural frequency of the test subject The video below demonstrates the phenomenon of mass loading and the…
The intention of this article is not to present any new scientific theories or ground breaking techniques, but to introduce new users to hammer impact testing and remind seasoned technicians of a method…
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? (more…)
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. (more…)
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 techniques. But which one should you use and why?
(more…)
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 (more…)
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…
“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.
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. (more…)
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. (more…)
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. (more…)
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? (more…)
Generally. when developing and testing bearings a simple step by step procedure should be followed.
When we are dealing with multiple measurements we often need to calculate a resultant vector to understand their combined effect. What do we mean by this? And how do we…
![Read more about the article [Video] How To Calibrate Microphones & Accelerometers](https://blog.prosig.com/wp-content/uploads/2011/10/microphone-640-250.jpg)
Here are two videos on a relatively simple, but sometimes misunderstood procedure – how to calibrate microphones & accelerometers (more…)
Here are two videos on a relatively simple, but sometimes misunderstood procedure – how to calibrate microphones & accelerometers (more…)
In one of our recent articles a question was asked regarding the practical use of real & imaginary type plots compared with modulus & phase type plots. In general, noise…
The use of a vibration condition monitoring system for monitoring vibration from large rotating machines fitted with fluid-filled journal bearings such as steam or gas turbines is well understood. Vibration from these components generally falls within the main harmonics or orders of the shaft rotational speed such as 1st, 2nd 3rd or 4th harmonic. Some energy may also exist below the 1st order, called the sub-synchronous component. Most energy exists below 1KHz and so standard displacement probes or velocity transducers are generally fitted. The Prosig PROTOR system collects this data in amplitude and phase form, relative to a ‘once-per-revolution’ phase reference signal, as standard and allows data to be displayed in real-time as mimic diagrams, trend plots, orbit and vector displays.
