Carlos Mora explains the different test methods to simulate vibrations closer to reality.
Field tests vs. Laboratory testing
We might think that the best way to simulate transportation in order to know the behavior of our load is to put the load in a truck and roll tens, hundreds or thousands of kilometers with it.
However, this technique allows us to analyze only the behavior of our cargo on that specific route, at that specific time, with that specific truck and with that specific driver. Too specific, right?
In this way, it is not possible to predict the real behavior of different packaging alternatives, means of transport and routes as would be done in a testing laboratory.
Therefore, it does not allow us repeatability, which is necessary, to be able to predict the real behavior of different packaging alternatives.
Another generalized idea is to record a particular route, only once, and then reproduce it second by second in a testing laboratory, for example in a vibration test system. With this alternative we can have a repeatability that we did not obtain with the previous solution. However, we still have the same problem with only playing a specific route at a specific time, with a specific driver and truck.
The solution to the repeatability problem, therefore, is the vibration table, a system that allows you to reproduce vertical vibrations and angular movements in a testing laboratory, in the case of our patented Vertical Vibration + Pitch & Roll system. generated during transportation.
Power Spectral Density (PSD)
In order to reproduce these vertical vibrations and rolls and pitches, and eliminate the problem of not reproducing the same route over and over again under the same conditions, we work with the so-called PSD.
Power spectral density (PSD) is the variation of energy within a vibrating signal as a function of frequency per unit mass. In the packaging industry, power spectral density analysis is used to measure the ability of vibrations to affect merchandise.
Once the data of a certain route has been obtained thanks to a data recorder such as innRecord, which allows us to record all the vibrations and angular movements of a transport, we can obtain the PSD of this trip. This PSD is nothing more than the transformation of our signal from the time domain to the frequency domain: it indicates the different levels of intensity of each of the frequencies present in the vibrations transmitted in a transport.
When we introduce these PSDs in a vibration table, it combines these different intensities and frequencies to generate a random vibration with normalized deviations. This allows us to statistically simulate what usually happens on the recorded route, in the testing laboratory, in order to reproduce statistically probable trips of the recorded and analyzed trip. That is, thanks to that PSD, you not only reproduce that particular moment, but other signals are also generated that statistically can occur in that route, increasing or decreasing the intensity of the vibration in the different frequencies.
With this we can already predict what our cargo can really experience during a transport with the indicated conditions.
What happens if I don’t have a specific route for which I want to design or optimize my packaging?
For this, there are international standards widely used at an international level, such as the ASTM, ISO, EN and ISTA procedures that give us this job done, providing us with the aforementioned PSD to introduce them directly into the innWave vibration machine of our testing laboratory.
For example, some ISTA procedures in which vibration systems are used are:
- Vertical vibration machine: Procedure 1A, Procedure 1B, Procedure 1C, Procedure 1D, Procedure 1E, Procedure 1G, Procedure 1H, Procedure 2A, Procedure 2B, Procedure 2C, Procedure 3A, Procedure 3B, Procedure 3E, Procedure 3F, Procedure 3H, Project 3K, ISTA 4 Series, 6-FEDEX-A, 6-FEDEX-B, Project 6-AMAZON.COM-SIOC,Project 6-AMAZON.COM-Over Boxing y Project 6-SAMSCLUB.
- Vertical vibration machine + Pitch & Roll: Procedure 3A y ISTA 4 Series.
To carry out the ASTM vibration tests in Safe Load we have the Vertical vibration and vertical vibration + pitch & roll system that complies with the ASTM 4728-17 and ASTM D999-08 standards.
This is the case of other regulations, to comply with the vibration tests it is necessary to follow a series of established guidelines, for example, in the UNE-EN ISO 2247:2000 or the EN 15552: 2008.
Advantages of Safe Load TT vibration tables
The Safe Load TT innWave family products offer a wide variety of solutions to optimize not only packaging but also all products exposed to vibrations.
Our systems are tailored to customer needs and also feature an intuitive controller developed by vibration experts at the University of Victoria in Melbourne, Australia, making innWave products the best solution for vibration simulation in packaging.
Would you like to know which is the best vibration machine for your testing laboratory? Get in touch with us and we will advise you to find the most suitable transport simulation equipment for you.
