Frame Analysis - Fixed/Pinned Constraint

[pompeo79]

Hi, i have  a few question about Frame Analysis in Inventor.

To do so, i will analyze a solved problem to compare with Inventor results.

-I have a simple beam, constraints and forces as figure:

-Length 6 m, a fixed constraint on the left and a slider joint on the right.

-A continuos load of 22 KN/m for the first 4 m (from left)

-A force of 30 KN after 5 m  (from left)

With a Constraint reaction analysis:

And the theoric results of the constraints reactions:

Now, in Inventor i obtain quite differents results.

Using Inventor 2013, SPacks installed.

1) First attempt.

(You can open assembly1.iam, and simulation1, in frame analysis enviroment)

I put correct forces (ignore gravity) and fixed and floating constraints.

My Ya reaction= 79134,259 N

My Yb reaction= 38865,741 N

Quite different from theory results. Where i am wrong?

2) Second attempt.

(You can open assembly1.iam, and simulation2, in frame analysis enviroment)

I put correct forces (ignore gravity) and both fixed constraints.

My Ya reaction= 64148,148 N

My Yb reaction= 53851,852 N

A little better, but still not correct and the second fixed constraint not required.

Where i am wrong?

Thanks for support!

Pompeo

p.s.  attached the zip with  the assembly

[jingyi.liu]

Hi Pompeo

I checked you data and simulation result, it seems you choose wrong constraints for the first node( left), it should be pinned constraints other than fixed, noticed in your FA simulation result, there is moment exisitng on the first node.

[pompeo79]

Hi Jingyi,

thank you for the answer and support.

I tried firstly as you show, but i was intimidated from this message:

Can i ignore this message and pass over it?

[jingyi.liu · Accepted solution]

Here is a similiar case in the Forum, you can view the reply by Hugh Henderson, he explained why the warning message popped out.

In your case, you can ignore the warning, you can get the same calculation result like you do it manually.

http://forums.autodesk.com/t5/Autodesk-Inventor/Frame-analysis-UDL-and-Point-Loads/m-p/3653386/highl...

[pompeo79]

Thank you Jingyi!