Interpreting FEA Results

[Anonymous]

Hello all,

I am working to measure the strain of this device using strain gauges.  I am having trouble interpreting which strain results from Inventor to match up with my physical test.  Below are the .ipt files, as well as images showing the orientation of the strain gauge. 

For the orientation I have attached, I suspected that I would use the strain_xy results from Inventor; however, those results are extremely low.  

FEA Results: strain_xy = -1.97 microstrain

Strain Gague Results = strain = 225 microstrain

I'm fairly certain that I am not using the correct orientation in Inventor, but I am unsure which one to use.

Any advice would be much appreciated,

Thank you.

[johnsonshiue]

Hi! This kind of discrepancy is usually due to incorrectly defined gravity direction or wrong material style. Could you share the files here? Forum experts can take a look and comment further.

Many thanks!

[Anonymous]

Hello Mr. Shiue,

I am having trouble attaching the files.  I am trying to attach the assembly file, and the 2 part files that make up the assembly.  I attach all three, then click the "post" button, however, the page refreshes and directs me to a fresh "reply" page removing the attachments.

[johnsonshiue]

Hi! The forum is acting up again. You will need to zip up the files and then attach the zip file.

Many thanks!

[JDMather]

I can't do much interpretation based on mere images, but my guess is that you almost certainly have the gauge installed incorrectly.

In fact, I suspect that in this particular case the only gauge that would return useful information is a rosette.

So two compounded issues.

1. Is the gauge installed correctly (or even the correct gauge for the application)?

2. Is the virtual analysis set up correctly?

[Anonymous]

Thank you for your response.

When you say that you suspect the gauge is not installed correctly, are you implying a poor bond between the gauge and the surface, or that the gauge orientation is incorrect?

I have mounted one horizontally, and another at 45 degree angle, which would give me the same data as a rosette, right?

I'm fairly certain the bonds and solder connections were good, all of the readings were stable, I am having trouble making sense of test results and matching the strains to the FE results.  

I have attached the files below.

Thank you.