Simulating a Load Cell in an Assembly Test? 1

[metalman8357]

Hi all,

I'm working on simulating tests that we run out in the lab with FEA and I'd like to be able to compare the data in a meaningful way. For example, we generally apply a tensile or compression load to an assembly and we are able to monitor Load vs. Crosshead displacement. As a result, an assembly will continue to take an increasing load until a peak load is reached and the load will continue to drop off below the peak as the assembly deforms and can no longer carry the peak load. My question is, is there a way to model a load cell or reference part that I can put into my assembly where I can specify a prescribed displacement (0.100 in/min) and then monitor the load like a load cell. I'm assuming there's a simple trick that I can use but I've yet to really figure anything out yet.

Any suggestions would be helpful.

Thanks,
M

 

[rb1957]

if you apply an enforced displacement load (ie displace a node "x"in) then there are several ways to extract the applied load.

1) the OLOAD matrix might give you something,

2) the sum reactions certainly will,

3) doing a GPFB at the loaded node certainly.

clearly i'm using NASTRAN-speak, but you should be able to find the applied load in whatever code.

Quando Omni Flunkus Moritati

 

[metalman8357]

Can you elaborate on these methods? If I were just doing a simple tensile test on a dog bone plate of steel and I had an enforced displacement how would I measure the applied load and where? I'm using Autodesk simulation so I'm not certain that I can check the OLOAD matrix or do a GPFB.

 

[rb1957]

1) you can apply the displacement as a load, and read the reactions to find out how much load had to be applied to achieve the required displacement.

2) possibly autodesk has something like NASTRAN's Grid Point Force Balance, where it tells you each element's internal force at a grid (=node).

3) OLOAD is NASTRAN's analysis of the applied loads ... it say's "ok, you've applied these forces and these moments about the origin, and i've created reactions that match (aren't i clever)"

1) is sure-fire, 2) and 3) are maybes

Quando Omni Flunkus Moritati

 

[rb1957]

of course the other approach would be to apply a load and see what displacement you get

Quando Omni Flunkus Moritati

 

[metalman8357]

I like the first technique. Thanks for the suggestion I will play around with it and see if it works out.