Simulating a simple supported steel "beam"

[franciscocfseixas]

I'm fairly new to Fusion 360, although I'm used to other 3D modelling programs.

I'm trying to simulate a square (20x20mm) hollow steel beam supported on both ends by a simple steel bracket, attached to a wall.

 

The expected outcome is for the beam to bend down in the middle, while both ends lift slightly from the support. The support

I've tested this with a vertical force applied to the top of the beam.

For F=800N, this is the result: 

But, for F=600N, this happens: 

And, for F=400N, it's back to the expected result: 

I've only changed the applied Force between simulations. Why does the beam seem stuck to the support when F=600N?!

Also, question 2: is Fusion 360 simulating the force applied to the support by the beam? It doesn't look like it, but that's one of my goals as well.

I have attached the model file.

Many thanks!

[JHRendon]

When I check the DOF it looks the beam is not fully fixed, Maybe there is a problem. Another thing is the 400, 600, 800 N would be applied in all that face of the beam? or only in the middle of the beam?

[franciscocfseixas]

Hi, and thanks for your reply.

The beam should not be fixed, just supported by the brackets. The force is to be applied evenly to the top face of the beam.

[jhackney1972]

I do not see the results you do.  The displacement at the loads you specified are:

200N - 21.62 mm

400N - 40.1 mm

600N - 58.02 mm

Also I wanted to mention if you wanted to apply the load only to the exact center of the beam, you need to define a new face there.  This is done in the model by sketching a small circle on the face of the beam and then using the split face command to cut the face with that circle.  This face can be used to concentrate the load on one small area instead of the complete beam length.

You also wanted to know the for reactions on the supports.  I believe all you have to do is change your results to report Contact Pressure and these will be displayed.

When I opened up your model I noticed you did not have Gravity check under your loads for your simulation.  Don't forget that.  In fact if you take off all loading and only turn on Gravity, the beam has a displacement of over 2 mm.

[JHRendon]

I have checked with the two cases 600 and 400 and I got the same results as you. With the 400 N there is more displacement (37.66 mm) than the 600 N (10.04 mm), stress, case 1 (143.1 Max) case 2 ( 194.4 Max). 

Remember that you are applying the 400 and 600 N in the top face. So in case 2, 600 N are applied in the middle but also at the sides, maybe that's why the beam is not bending in the way like in case 1 that 400 N are applied in the middle and the sides but are not enough N to the sides to keep the shape of the beam.  Or maybe it does not has sense. 😞