Measuring small deformation caused by temperature?

[Bouta]

Hi, I am looking for a type of tensometer (or something like that) to measure strain/deformation in a plastic housing caused by thermal expansion. According to a super straight-forward hand calculation the deflection at a given point will be 1.3mm. The temperature change is from 23 to 80 Celsius.

I have very little experience with this type of applications. I am more interested in a relative change in position between 2 points (distance is about 330mm) rather than the local strain in the material itself. What would you recommend?

 

[IRstuff]

If you're interested in measuring deformation, then measuring strain is simply an added complication. There are lots of different instruments for measuring deflection, such as laser distance meters or capacitive proximity meters.

 

[Bouta]

I need to put the device in a climate chamber so I don't have much space for additional equipment like laser distance meters and also - I have no certainty how the measuring devices will be affected by temperature. So I would think that actually attaching a tensometer to the surface of the housing might be an option?

 

[3DDave]

A tensometer will be affected by temperature, just less than the plastic. It will probably under-report.

Since it is plastic, you could just submerge it into water on a hot plate and use a caliper. Stir to prevent sticking and to ensure the water is uniform in temperature during the process. If you don't want to risk an expensive caliper, use a transfer caliper to capture the measurement and move it to another measuring device:


If you don't like water, use the transfer caliper and, upon opening the door, work fast.