New to Mecway - API Bolted Connection

kuhtip

Hello everyone,

I work at a small company and from time to time we need some FEM Simulations. I quiet well know Femap. At work we are just using NX Design Simulation, which capabilities are not that good, especially when you need beams or shells.
I did some reasearch and came to Mecway, which i really like from first views

I downloaded the 1000 Nodes test version and iam very happy with it. When i come back to femap there is some api to idealize bolted connection, which connects each end of a beam element with an RBE2 element to a bunch of pre-selected nodes.
I tried to make a code to recreate this kind of feature.

There are some points where iam getting stuck. I managed to select some nodes and create a mid-node and connect the selected nodes with a line2 element to the mid-note.
I would like to give those beams mechanical properties like youngsmodulus, diameter, rectangular bar, poisenratio, density...
i looked in the api reference "mw.material_property(material, property)", but i didnt got it running so far.
Is there also a way to create a button, to give the user a chance to re-select some other nodes before creating a new mid-node? now it just creates the same beams like before when you continue the code.
I was thinking about the same kind of behavier when you select the open cracks feature. Where is a button to repeat the code after you pressed it or something like that.

I appreciate every kind of comments and help and i wish you a good start into the new year

ps.: attached you see a bolted connection in Femap and the code i made so far.

Sergio

I have made something similar, I use two scripts, one for create a node in a circle based on three selected nodes. The second one takes the selected nodes and creates the spider and material. The user must select the center node as the last one in order to work



The problem arise when the user create the second spider, as is now the script, it create the second spider, and a new rigid material, but it doesn´t assign to the new spider. I don´t have the skills/time to fixe it, it should check if the material exist and don´t create a new one.

kuhtip

@Sergio thanks for your kind answer. Glad to see that you managed to asign properties

cwharpe

@kuhtip: When comparing (Mecway) Spiders of beam elements with FEMAP RBE2's, some adjusting of beam properties is necessary to produce an equitable simulation. Even so, an approx. 2-3% deviation between solutions is expected. (Ref. subject near https://mecway.com/forum/discussion/comment/6093#Comment_6093)

@Sergio: Nice example of implementing API. Slow time of year, so I tweaked a couple of revisions to your script. Wasn't sure if you preferred:

• A new material paired with a new spider component for each script cycle OR
  
• The SAME material with each new Spider component " " " " OR
  
• The SAME material with the SAME component for all script runs
  

Cheers.

Sergio

Hi @cwharpe ! Thanks for taking time to fix my poor man script. I think that the logical is that all the beam elements share the same material and component.

JohnM

@kuhtip I think what you are discovering here is not just how to set up a bolted connection but also the "killer app" to Mecway - the users in this forum

We have been using Mecway for 8 years now, with many licenses. Rest assured you have chosen well!

cwharpe

@Sergio: Same/Same. Makes sense. That's how I've been using them. If another size fastener happens along within the model, I've just renamed into a different component.

Try this...

Sergio

@cwharpe about putting different spiders from different fasteners in different components, have sense? I meant, is a resource to connect to the beam that simulate the bolt shaft, only those beams must be in different component in case of different bolt diameter

cwharpe

Just that I've followed advice I read somewhere to "Fill the Volume" of the bolthead spanned when sizing spider cross-sections. Haven't quantified yet how important that is, since stiffness = E*I is more easily adjusted through Youngs Mod.

Lot's of ways to achieve similar results, I assume.

kuhtip

@cwharpe thanks for clarification. Nice work there!

Thanks for sharing your py-files. It really helps me a lot

i have now also made 2 scripts to model the bolted connection.

First you need to make 2 Spiders, one after another, via "Spider_for_Bolted_Connection". Select the nodes first and create a mid-node.

Afterwards activate "Create_Bolt_between_last_2_nodes" by entering the bolt diameter. The bolt is modeled between those notes with the right diameter. And the bolt diameters are all arranged into the Component "Bolt_Mx" where x is the user input.

is there a way to manipulate the units in the files? I like to model in mm and MPA.

Sergio

@kuhtip there is no way by the moment to identify the user unit system, so you must work in meters and Newton in your script as is the internal unit system that use Mecway.

Would be great to have a custom tool bar (floating?) to add this kind of scripts, I use several ones and the menu feels a little uncomfortable. Another usefull thing would be the possibility to add a custom tip to the tools, in the menu and/or in this custom tool bar.