Acceleration and energy absorbed: How?

[John Ryan]

I am doing a project to test an analysis how effective a bicycle helmet is during impact. I have never used LabView but am learning at the moment. I have to capture acceleration(accelerometer) and energy absorbed(force transducer)and plot them on waveform graphs. Any help or advice would be great

[S.Klumpp]

Hi John,

I'm not used to those measurement devices you are using, so before I can help you more closely, I have a few questions:

1.) Which output do those measurement devices of yours produce?
2.) Which DAQ card do you use to read the output into the PC?

Greetings...

Stephan

[John Ryan]

Thank you for youe swift reply Stephan, it is much appreciated.They both give me an output of voltage and the card is DAQ6024E> hope you can help
Cheers
John

[Aname]

Hi John,

You need some way to calibrate your sensors and you may need some signal
conditioning. Not a lot of experience with accelerometers, but like any
analog device, you need to know what comes out when you put something
into it. Then you can use a look up table to translate the voltage into
the acceleration. Labview has an express VI called "Mapping and
scaling". You simply put the voltages in one column, and the desired
readout in the other column.

For example if you exert an acceleration of say 3m/s^2 and you get a
voltage of 200mV from the sensor, then one line of the table would have
"0.2,3". For 6m/s^2 and a known voltage of 300mV you would have a line
"0.3,6" and so on. The more calibration data points the more accurate
yo
ur results will be. Then you can use "interpolate" function and the VI
will calculate the data points between the known data points.

If the sensor comes with a formula then you can use the same VI to input
a formula. eg. acceleration = volts * K. where K is some constant.
Otherwise if the sensor comes with a graph, then just take multiple
points from the graph and input them into the table for the mapping and
scaling VI.

This VI maps the input voltage to some number to represent its meaning.
I know this VI exists in LV7.0 and but not sure if it is in lower revs.

You can create the algorythm yourself if you don't have it but obviously
more time consuming.

To translate to force, simply have a vi that multiples the measured
acceleration by the known mass.

Hope that helps.

JT

[labview-programmer]

Hi,

I know this is a very old post, but just that this info might be beneficial for someone looking to do impact testing of helmets.

The formulae of energy dissipated, Head Injury Criteria, 'Gadd Severity Index', Velocity at Impact, Dwell Time and others used for testing the performance of Helmets against impact can be obtained from this post. Here the whole project of Impact Testing of Helmets using LabVIEW and sbRIO is described - http://wp.me/pOsP9-I

A small video is here: http://www.youtube.com/watch?v=dtRdMEoeQbc

Please note the video shows one of the primary two arrangements.

More info to follow real soon 🙂

[rayen]

I am newbie in labviewprogramming. Then I have enquiries about my project which is using labview. I amusing impact test with NI DAQ 6251, impact hammer B&K 8200 andaccelerometer B&K 4371 then attach it in a structure. I have done somenecessary setting and it works. I can get some graphical result for magnitude (dbchecked) phase, coherence and others are works too.

But, it is very important to meto get the value of the force when I hit the structure with the hammer. I shouldget this force value, to make the amplitude respond from accelerometer relativelycompared by the force.  Can any one helpme what should I do with – especially – the labview program, so that it canresult in the force data. Then, how to get the value of the amplitude per force(m/N, in Y axis) versus the frequency (in x-axis) in a graph/chart. I really needyour help for my research. 

[Dillon64]

Hi Aniket,

I know this is also a very old post, but I am looking into doing exactly what your post mentions, acquiring Gadd Severity Index data from head drop testing. Unfortunately it appears the links on your post, with the exception of the video, have expired. Is there any chance this information is still available somewhere?

Thanks,

Dillon

[johnsold]

Dillon,

Aniket was last logged into the Forums in 2011 so it is unlikely you will get a response.  You can see the public profile for a member by clicking on their username at the left of each post.

Lynn