Static Structural simulation of a involute spline

[Konstantinos_29]

I am trying to do a simulation of an involute spline in ansys without any luck. I have tried anything that I have thought but nothing worked can someone help me on how to do it?

 

[FEA way]

What did you try and what failed (what issues did you encounter) ? Can you show the geometry and describe what should happen in the simulation ?

 

[Konstantinos_29]

I made the geometry in the inventor using the involute spline tool. I insert the geometry in ansys like an assembly I add the corresponding connections and try changing every setting that I could think of in the connections. I put torque in the one connecting part and fixed support in the other connecting part. All of them gave me a very bad safety factor of 0.2 and even smaller and couldn't converge somewhere (the stress only goes up - I was expecting a safety factor of two - I am a student and I do not have too much experience with splines so I may be say something wrong) with the concentrating stress being at the end of the connection. I don't believe that this is right as I have found simulations that don't have this problem but they don't explain how they set them up the only thing that they are saying is that they used a custom mapdl. Tell me anything stupid things that I could have set up wrong as I am new in the simulation world. I am attaching one image making the one out of two parts invisible in order to see better the solutions that I got.

 

[SWComposites]

Oh my. You should be learning FEA with MUCH simpler models first.

What are you using for material properties?
What are you using for a failure criteria?
Are you running a linear static solution?

 

[Konstantinos_29]

For material, I tried to use the materials that is already in ansys library like static structural. For failure criteria, I used von-mises and i am running a linear static solution.

 

[ThomasH]

What is the purpose of this exercise? You say that you are a student but if this is for school I doubt you have started the model as the teacher intended.

You have used a tool in Inventor to create the geometry. That probably means that you have imported two volumes into Ansys, and then meshed with volume elements? If that is the case you probably have a very large model in terms of elements. Based on the figure it seems like a large part of the model is redundant.

I don't mean to be rude, especially since you are a student. But if this is a school assignment, what is the purpose with the exercise?

Also: Student posts should be in the student forum .

 

[Konstantinos_29]

Firstly it's not for the school I haven't even taken this class yet the little things I have learned in FEA its from searching on my own on the internet. The purpose of all of this was that I started trying to simulate a gear that had a spline and I just analyzed it without taking it into consideration and just calculated it in hand and I was like mmmm why don't also put it in the simulation so here I am. I know it's not the smartest thing that I have done and maybe it isn't correct but I am just trying to learn fea and make myself a better engineer I stumbled across it so I am trying to do the stupid thing that I thought until I know with certainty that what I am doing is stupid and not correct. Secondly, I know there are ways to make the model much smaller (which I have done in some way) but until I know what is really happening in this simulation I don't want to think about that. Thirdly sorry I didn't know that this is only a professional forum and students have their own forum on this site.

 

[ThomasH]

I see. I can only agree with what SWComposites said. Start with much simpler models.

The idea with a smaller model is that it is easier to understand how it works. The software will solve the problem as you set it up. So I think your reasoning regarding the model size is a bit backwards.

I wish you good luck.

 

[Stick.]

You're effectively trying to run a 5k here before you've even learned how to walk. As others have said, start with a simpler problem or just hold off until you've taken the FEM course at your school. If you want a jumpstart on learning some concepts, look up stress singularities. That ought to help you understand why your stresses don't converge and only shoot up towards infinity. Also, whenever you're looking at high stresses in very small areas, it's a good idea to display the mesh on the result plot so you can see if your results are mesh dependent and to see if you're dealing with a stress singularity or a "real" stress. Finally, doing a hand calc like you've already done is good practice. You should pretty much always do a hand calc so you know what ballpark your results should be in (this helps detect large issues in your model setup).