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nch315
Posts: 3
Registered: ‎12-07-2013

Bridge design: errors when drawing in Z direction

140 Views, 4 Replies
12-07-2013 11:44 AM

Hello,

I have set up my file according to a previous tutorial that worked, and I currently have beam members in just the X-Y plane. I also have a few nodal forces in the Z-direction. With the settings that I have, I can run the simulation, but as soon as I attempt to draw members in the z-direction, I receive errors. I have tried to change the orientation of these beams, but that hasn't changed anything. What can I do to fix this?

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Valued Mentor
AstroJohnPE
Posts: 510
Registered: ‎08-30-2012

Re: Bridge design: errors when drawing in Z direction

12-09-2013 05:52 AM in reply to: nch315

 

Hi nch315,

 

Did you try looking up the error message in the Help? That would be my only suggestion.

 

Otherwise, a little more information might help someone to solve your problem, such as

  1. WHAT is the error message?
  2. When does the error occur?
  3. What type of analysis are you performing?
  4. What version of software are you using?
  5. What was the phase of the Moon when you last tried? (or the date; I'll calculate the phase ;-)
  6. How many parts are in the model?
  7. What are the element types for all of the parts?

 

John Holtz, PE
Mechanical Engineer
Pittsburgh, PA

16 years experience with Simulation Mechanical
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Member
nch315
Posts: 3
Registered: ‎12-07-2013

Re: Bridge design: errors when drawing in Z direction

12-09-2013 09:39 AM in reply to: AstroJohnPE
Sorry for not being more clear. The error was -503 for the solver. I was
using Autodesk simulation mechanical 2012.

I received the error when working on a project for a class and a few of my
classmates had the same issue. I used a classmate's file that was working
and was able to complete the project, however I did find it an interesting
issue.

Essentially, the model when the issue would occur consisted of around 15
beam elements in the xy-plane, as well as gravity and four nodal point
loads in the negative z. Analysis would run correctly for this structure,
but as soon as I'd draw beams in the z, I would get an error. All element
types were beam with aisc 2005 W type cross section 12x72. Also, all
elements were in the same layer and part. Units were in SI.

Also, thank you for your response and aid.
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Valued Mentor
AstroJohnPE
Posts: 510
Registered: ‎08-30-2012

Re: Bridge design: errors when drawing in Z direction

12-10-2013 10:55 AM in reply to: nch315

 

I'm not sure what the 503 error was, but it is probably an indication that the solver encountered some type of error (math error? poorly defined stiffness matrix?). One solution may be to go into the Analysis Parameters ("Setup > Model Setup > Parameters"), go to the solution tab, and change the type of solver. (Since your model is small, you can try the iterative. If that does not work, then change to the sparse. If it was a large model that ran for a long time, I would look at the summary file to see which solver was chosen as the "default" and then manually switch to the other type of solver.)

 

When you drew the new beam elements extending in the Z direction, did a node on the new beam coincide with a node on the existing structure? One important thing to remember in Sim Mechanical is that internal forces and moments are transmitted from one element to the adjacent elements through the node. So if the nodes are not connected, there will be no load transfer. Typically, nodes are connected because the two elements share the same node number. In the case of surface contact, the software creates an element that connects the two nodes together, and part of the solution is whether the two nodes come into contact (the nodes move closer together) or separate. In some cases (MES and thermal?), these contact elements are not shown to the user. Another, advanced method of connecting nodes together is through Multi-Point Constraints. Most users never use these manually, but the software creates them automatically in some situations ("smart bonding", cyclic symmetry, and ???).

 

John Holtz, PE
Mechanical Engineer
Pittsburgh, PA

16 years experience with Simulation Mechanical
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Member
nch315
Posts: 3
Registered: ‎12-07-2013

Re: Bridge design: errors when drawing in Z direction

12-10-2013 05:36 PM in reply to: AstroJohnPE
Thank you for the advice. I will keep that in mind in the future.

When drawing in the Z I would either manually designate the points, which
would be the same as the constrained nodes for one end of the four lines,
or I would allow the "lock" function to connect the lines to the points.
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