James Wren is an Application Engineer and the Sales Manager for Prosig Limited. James graduated from Portsmouth University in 2001, with a Masters degree in Electronic Engineering. He is a Chartered Engineer and a registered Eur Ing. He has been involved with motorsport from a very early age with special interest in data acquisition. James is a founder member of the Dalmeny Racing team.
Microsoft has recently announced that security updates and patches for its Windows XP operating system will end from 08 April 2014.
Many organisations are now having to update older PCs and laptops to Windows 7 or Windows 8. Continue reading The end for Windows XP. Are you ready?
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. Continue reading What Type of Accelerometer Should I Use? IEPE, Charge or Bridge-based?
The DATS Modal Analysis software consists of Hammer Impact Testing, Modal Analysis & Structural Animation (often referred to as Operational Deflection Shapes or ODS and Running Modes). Having measured and analysed your data the Structural Animation software allows you to visualisation your structure under certain operating conditions. These visualisations can then be saved as AVI files. This video shows you how…
When working in the synchronous/angle domain, how many samples per revolution are required to study a particular order.
To study the nth order we need samples per revolution. Continue reading How Many Samples Per Revolution Are Required To Study A Particular Order
The DATS Rotor Runout Measurement package can be used on any shaft where the following probes are available…
- A LVDT (Linear Variable Differential Transformer) probe. This is basically a contact probe. This will allow the measurement of the shaft total runout*.
- If an electrical runout measurement is also required then an additional eddy current probe (also known as a proximity probe) is needed. This is a non contact probe and can be used in conjunction with the LVDT to measure the electrical runout only.
- A once per revolution tachometer is also required. This could be optical, proximity, magnetic and so on.
With these three sensors it is possible using the DATS Rotor Runout Measurement package to find both electrical and mechanical runout.
* Total runout is a composite tolerance including the effects of cylindricity and concentricity, co-axiality, straightness and parallelism along the axis.
A tutorial by James Wren (Prosig UK) on how to use the reference cursors in the DATS software to precisely measure features in your data.
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? Continue reading How do I find the natural frequency of an inlet manifold?
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 Continue reading How do I perform vibration analysis on a cylinder head and inlet manifold?
The relationship between sample rate and maximum frequency that can be analysed (called bandwidth) is a factor of 0.4. Or to look at it another way the sampling rate is 2.5 times the maximum analysis frequency.
The value of 10,000 Hz is multiplied by 2.5 to allow for an anti-alias filter during the capture of the data. An anti-alias filter is set to 0.4 of the sample rate, thus the bandwidth or frequency content that can be studied is 0.4 of the sample rate.
For example, when looking to study a frequency up to 10,000 Hz what sample rate should be used?
So we multiply by 2.5…
10,000 Hz x 2.5 = 25,000 Hz
So the sample rate should be 25,000 samples per second to allow frequencies of up to 10,000 Hz to be studied.
James Wren (Prosig UK) explains how to store FRFs, coherence and/or time series data in modal hammer testing using Prosig’s P8000 & DATS software.