Learning Forum

[JoshuaValdivia]

Hello, 

I am having trouble adding connections in between beams for my Beam Element Model. I was using auto generate connections but I was getting deflection values 3 orders of magnitude higher than I was supposed to be. I assume the connections are much stronger than they should be and I'm not understanding why. I started using end release connections but most times when I choose a vertex the end release connections don't allow for it. Another question is whether or not I should be using end release connections of joint connections for by beam element model.

Thanks, I have included a screenshot and the file I'm using in this message.

[peteroznewman]

When you say, "but I was getting deflection values 3 orders of magnitude higher than I was supposed to" I am confused by what you mean by the value you were "supposed" to get.  Do you mean the model was giving deflections thousands of times larger than an experimental measurement?  That sounds like a mistake in the model, either in the materials, the beam cross-sections, the loads or supports.

It looks like your structure is a welded frame and so I would not expect it to need any beam releases. 

If you were designing a suspension, where there were joints between the links, and you were modeling that with beams, you might use a beam release to represent a joint.

Please show a sketch of the loads and boundary condition on this model. Show the materials and the beam cross-section properties.

To attach your model, you must create a Workbench Project Archive .wbpz file by following these directions, and you can attach that model after you post your reply.

[JoshuaValdivia]

Thanks for replying,

I have run these sims in another program but am having trouble getting it to run on Ansys so I know what my vertical deflection should be.  And you are correct, the structure is a welded frame.  And to clarify, the model was giving deflections thousands of times lower than simulations I have previously done on other software.

 

These are the supports

 

And these are the loads

I have a lot of different cross sections that will be tough to show in an image so I have attached the archived file to this post and the material is 4130 Chromoly Steel. 

[mekafime]

Hi, I'm reviewing what you uploaded but the model runs well, when you say that the deviation is greater than what you calculated, how much higher is it?

[JoshuaValdivia]

The direction deformation in the area pictured below should be about .3 millimeters. Instead I'm getting .06 mm.

[peteroznewman]

You built the same model in two different programs and got two very different results. How do you know which model is closer to the "truth" and which model has the error in it?

I recommend you build a much simpler model that has a known solution in each program and see if you can get the same answer on the simple model first.

[JoshuaValdivia]

The first version is closer to the truth. The second was attempts at using different kinds of connections. I mainly posted this to get feedback as to whether my connections are being set up correctly for a beam element model. 

 

Thank you for your feedback, that seems like a good way to find the solution to my problem.