Question of FEA analysis in a simple assembly

[zmarcoz]

Dear all,

I have two parts that put together. Basically a triangular ring is put into a hole of a hollow cylinder. The triangular ring (0.5 dia) could freely move inside the hole (0.625 dia). 

I need to do a FEA analysis, my steps are
1. I mate the centerline of the hole to one of the axis of the triangle ring, so they line up (as least visually), then click OK. AND then delete this constraint
2. Start FEA analysis, put fix constraint at the bottom of the cylinder, add force to the ring
3. ADD 2 contacts (separation, no sliding)
4. RUN

I cannot believe the result. I apply 50 lbf only, but the safety factor is close to zero. Do my steps right??? 

Pictures and parts are attached. Inventor 2014

[JDMather]

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@zmarcoz wrote:
1. ... AND then delete this constraint
2. .....add force to the ring
3. ADD 2 contacts (separation, no sliding)

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1. Why are you deleting assembly constraints?  (don't)
2. You are doing a Static Analysis - the ring should be constrained straight down with the given force (it would move as you have it - not static).

3. Use Sliding - No separation contacts.

4. The force in your attached file is set considerably higher than 50lbf.

[JDMather]

I would also question the logic of why you used a circle edge for the Fixed Constraint rather than a face?

What does the rest of the assembly look like (were that tube attaches)?

[JDMather]

If you want to test at various angles of load, you should -

Model your ring with symmetry about the origin (your Sketch1 is not constrained?

Turn on the axis perpendicular to the contact (parallel to the load).

Add an angle constraint between the ring and the pipe (for easy editing).

Use the Axis to set the load direction.

[JDMather]

Did you ever get this figured out?

Was this a school assignment?

Did you ever get this book as suggested a year ago?

http://forums.autodesk.com/t5/Autodesk-Inventor/How-to-do-dynamic-analysis-on-two-gears-Problem-of-i...

Also, for your sketches on the triangular ring you might read this

http://home.pct.edu/~jmather/SkillsUSA%20University.pdf

[zmarcoz]

First of all, Thanks so much JDMather.

I was very busy in the last couple days, so I did not have time to follow your suggestion.

I read all your replies (Thanks again). I just have chance to test the suggestion from your 1st reply before I go to work today. Obviously, I need to follow your other suggestion. (1 min left before I need to leave)

I also go to amazon to see the book that you suggest. It seems like he has two books, one is for dymanic analysis and the other one is static analysis. I have had some background of the part design, so I want a book that only focus on analysis. I will read more from amazon tonight after work. (Need to go) 

[zmarcoz]

I tried to add the force in the assembly along the direction of the axis, but Inventor does not allow me to select it. Any idea?

[JDMather]

You do not have your axis selection (Direction) tool active.

You need to select the face on which the force is to be applied (which brings up another question) and then with your Direction tool active - select the axis.