How to modify parts section

[Anonymous]

Hello dear guys

I am beginner in Simulation Mechanical. I am going to do random vibration analysis on a structure. I modeled a structure in robot structural analysis, and since as far as I know there is no option for random vibration analysis in Robot, I need to do it in Simulation Mechanical. I save the model as DWG file and opened it in Simulation Mechanical, but in the first step, I do not know how to group the elements with similar sections. Because as far as I know, for each group we can assign only one section. On the other hand, as a default three groups have been created for my model,  and I select "Beam" as the element type, but when I click on edit element definition, it doesn't work and gives me an error saying that "the part does not contain valid geometry". I attached my DWG file. It is kindly appreciated if somebody can help me. Thank u so much in advance

Regards

[Anonymous]

Thanks for your reply John

The reason that I used Nastaran Solver is that with SimMech, the analysis cannot be completed and the software says that no masses were defined. You said that very few of my beams are connected. When I checked some of them, I saw that you are right. The lines are drawn at the centerline of the beams. In fact I saved my robot structural analysis file as DWG file and opened it in Simulation Mechanical software. So I want to correct them in simulation mechanical, not in AutoCAD. but it seems a little hard. I tried and I wasn't successful. Could you please help by at least correcting a few of the members and I will do the rest myself? Thank u so much John for all your helps and cooperation.

Regards

Mojtaba

[Anonymous]

Thanks for your reply John

The reason that I used Nastaran Solver is that with SimMech, the analysis cannot be completed and the software says the frequency cannot be calculated since no masses were defined. You said that very few of my beams are connected. When I checked some of them, I saw that you are right. The lines were drawn at the centerline of the beams. In fact I saved my robot structural analysis file as DWG file and opened it in Simulation Mechanical software. So I want to correct them in simulation mechanical, not in AutoCAD. but it seems a little hard. I tried and I wasn't successful. Could you please help by at least correcting a few of the members and showing me the process and I will do the rest myself? Thank u so much John for all your helps and cooperation.

Regards

Mojtaba

[John_Holtz]

Hi @Anonymous

The steps in Sim Mech are basically the same as what you would do in AutoCAD. These are the basic steps that you need to do:

When the line does not extend far enough to touch a crossing line

1. Set the selection method to vertices ("Selection > Select > Vertices")
2. Measure the distance from the end of the line to the crossing line ("Tools > Inquire > Measure"). You may need to measure a couple of different directions to get the desired DX, DY, DZ.
3. Now you have two options depending on the situation: draw a new line to "connect" the beams, or stretch the existing line.
   1. To draw a new line segment, first set the selection method to "Line".
   2. Select the line you want to "extend", right-click, and Inquire to get the part, surface, and layer numbers.
   3. Draw the line from the end of the existing line with the proper DX, DY, DZ ("Draw > Add > Line")
   4. To stretch a line, use "Draw > Modify > Point Move" and move the endpoint the proper DX, DY, DZ

Adding a node to a crossing line

In some cases, a line may meet with a crossing line, but the crossing line does not have a node that corresponds to the end of the line. So the two beams are not connected. You can try one of these:

1. the Intersect command ("Draw > Modify > Intersect")
2. delete the original crossing line and draw in two line segments to replace it. Naturally, you want to check the part, surface, and layer numbers of the line before you delete it.

After you get everything connected together, you will probably need to divide the line segments so that you can get stress and displacements along the length of each member.