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COSMOS Beam element

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getafix0

Mechanical
Sep 19, 2006
6
I am trying to analyze a beam element tube frame vehicle chassis model in COSMOS using the beam element analysis. I am running into issues with Cosmos telling me that "PCG Iterative solver stopped. Status Code 2: Preconditioner_fails_to_factor. May not have sufficient restraints. No results saved"

I have been trying to test the frame using multiple methods. The test work when I assign all tubes as beams (not trusses) with fixed ends. Once I attempt to input my suspension components as either trusses or beams with pins at either end this message appears.

I know I have sufficiently constrained the model as I have added 4 fixed points to the rear of the chassis, and applied my torsion loads to the front hubs.

What is causing this issue and how can I solve it?

Thank You
 
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First, Try using the DIRECT SPARSE solver instead of the this FFE solver.
If problem still occurs, Check the .OUT file and see which NODE or ELEMENT is problematic.
 
I tried the direct sparse solver and that did not work, it gave me another error. I have been looking in the .out files but it does not have a line that references what node was giving me an issue or matrix diagonal. It states what the error was, number of nodes, and what options I had, but that is it. Is there another error log file I can view? The error I get is "stiffness matrix diagonal is 0 at equation 125"

I tried to use a soft spring to stabilize the model and inertial relief and I get a solution, but a very unrealistic one. It also pops up with a large displacement warning. I will see if perhaps adding the steering tie rod will help stabilize the system. Any other ideas?
 
I tried the steering tie rod and now I get a new error, that says "excessive reverse offsets at two ends of beam". Any ideas of what that means?
Here are some pictures of what my current setup is:
chassisFEA1.jpg

chassisFEA2.jpg
 
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