# THE VR BLOG

### Posts by Topic

Did you know...

...that you can receive emails when a test is completed?

Is your lab facility backlogged and swamped with vibration tests that need to be conducted?
Are you concerned about when a test completes (or aborts) so that you can get another test running ASAP?

Topics: vibration testing

Random vibration testing has been around for quite some time. But traditional random vibration testing is Gaussian in nature. The averaging method used in random vibration testing produces a Gaussian distribution of data in which the highest peak accelerations are approximately +/- 3 times the average acceleration. Gaussian distribution has been universally accepted as a legitimate averaging technique, in part, because it has been assumed that “real-world” data is Gaussian.
However, several studies have determined that “real-world” data in actually non-Gaussian. Since this is true, the question is how can one make a random vibration test more realistic?

What is Gaussian Distribution?

With the use of statistics, one can find a number of interesting things about a set of collected data. For example, one can easily compute the mean and the standard deviation of a data set – statistical concepts familiar to most people communicating the average of the data set and the range in which most of the data points fall. But a less familiar statistical concept is the kurtosis of the data set. Kurtosis is a measure of the “peakyness” of the probability distribution of the data. For example, a high kurtosis value indicates the data is distributed with some very large outlier data points, while a low kurtosis value indicates most data points fall near the mean with few and small outlier data points.
If one evaluates a random data set, one will find that the data points will fall within +/- 3 standard deviations of the average (mean) (Figure 1). This is defined as a Gaussian distribution (kurtosis = 3).

Topics: random, kurtosion
Topics: sine, vibration testing
Topics: accelerometer
Topics: Transducers
Topics: FDS, Education
Topics: Education, Tips and Tricks
Topics: shakers
Topics: vr9500, shakers, Education