Hi,
I'm trying to model a hollow, rectangular cross-section beam. It is 0.6m high, and 0.45m wide. The walls are 0.01 thick, meaing the dimensions of the inner rectangle are 0.58m and 0.43m. The beam is 6m long, of the material "Steel, mild", fixed at each end, and with a force of 9800N applied on the top face.
The results Autodesk Inventor give me are very different to my analytical results.
My analytical results state the max stress should be 15.9MPa, and the max displacement 0.5mm.
However, Autodesk gives the max stress as 2.8 MPa, and the max displacement as 0.07mm.
Is there something I'm doing wrong?
I have tried using hollow beams with thicker walls, in case the thin walls were a problem, but I am still getting very different results.
Post part here and perhaps others can try performing the FEA on it to verify results.
Regards,
@christaylor92 wrote:...fixed at each end,.
Make sure the constraint application matches the real world and matches the hand calc.
I have found that often the and calc set-up doesn't match the real world constraints if care isn't taken.
Attach your file here and describe it's true attachments at ends and true area of load (across entire beam or in a specific area).
The CADWhisperer YouTube Channel
Thanks for your reply, I have attached the part in the post below yours.
The part is fixed over the cross-sectional area at each end, and the load applied over the area of the top face.
I do not see a simulation set up in that file?
No fixed constraints, no load?
The CADWhisperer YouTube Channel
I ran it through Sim-Mech 2014
Max Dis: 0.0377mm
Maxvon Mises: 1.735 N/mm^2
This is with both end surfaced fully fixed. Are you sure you don't mean "simply supported"?
I'm pretty sure it was fixed, but is there a way to simply support within autodesk?
You need to use the Vectors tab to control the directions of constraint
Use the pack-and-go for this as you have omitted all the FEA fiels
@Blair wrote:Use the pack-and-go for this as you have omitted all the FEA fiels
All the information is defined in the latest file - re-running the simulation recreates the missing data files.
The CADWhisperer YouTube Channel
@christaylor92 wrote:My analytical results state the max stress should be 15.9MPa, and the max displacement 0.5mm.
However, Autodesk gives the max stress as 2.8 MPa, and the max displacement as 0.07mm.
My guess is that the formula you used allows rotation at the ends (around the X-axis in this case) and probably translation towards the center (in this case Z translation), while in Inventor you have fully constrained the end faces. This results in tight ends (they remain vertical and fixed in place, no rotation or translation towards the center), and therefore less displacement.
Also this is a thin part (in relation to overall size). Using the Midsurface analysis might be better, but I haven't used that yet.
The CADWhisperer YouTube Channel
Thanks, used to Sim-Mech with the related files stored in a separate directory.
You are getting a "Thin-Wall" warning with this model. Results will be different than hand calculations
I would look at the PDF results I posted running Sim-Mech as more accurate.
Thanks, this could be the problem. But, I also conducted the analytical calculations with a solid beam, and it gave me very similar answers to Inventor.
Is there a way to adjust the constraints within inventor?
Expand the Contraints Box, double >> in lower RH corner.