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LMS Test.Lab Signature: Tracking on displacement string pot

I am using a VB8-II card with a string pot to measure displacement.   My displacement will go from 0 to 300 millimeters.  I am measuring a load cell on another channel.


I want to make a force-displacement curve where the force is tracked against the displacement every 10 mm from 0 to 300 mm.  How do I do this?


Re: LMS Test.Lab Signature: Tracking on displacement string pot

If you are using Signature Testing, there are two options.  First would be to put the load cell channel into the 'Static' group.  Note that this will change all of the channels on that card to the Static group.  If this isn't feasible, use a Virtual Channel to put the channel of the load cell into the Static group.  Simply make a formula where the formula is the is the load cell channel, like 'CH1' and then change the group to Static (maybe change the Point ID as well).


Next, in Tracking Setup you can now track on a static channel and select the load cell as your tracking channel with a minimum of 0, maximum of 300 and an increment of 10.  I'd also make the Slope Method 'Imm. Up' (Immediate Up) as you will never get below 0mm to start the acquisition.

Re: LMS Test.Lab Signature: Tracking on displacement string pot

Here are a few screenshots to help:


1. Setup of Virtual Channel:  Click in upper right and change Channel Setup to Virtual Channels.  Formula is CH1 (or other channel number) and set Group to Static:



 2. Tracking on Static Channel - In Tracking Setup worksheet, set mode to 'Tracked' and 'Tracking Method' to 'Static'.  Then the displacement channel can be selected from Tracking Channel.



3.  Bonus Tip: Calculate the Mean - To get the force-displacement curve, calculate the mean of the force in 'Online Processing' in 'Frame Statistics'. This will allow you to display the force versus displacement.  The mean is calculated on small frames (as set by the frame size parameter).displace3.png