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Spotweld (RBODY)

Hello,

I am working on crash analysis of a truck chassis on radioss. In my crash analysis project till day I have been connecting two components using the 1D spotweld panel. I just wanted to know if I am doing it right.

I go to the 1D spot weld panel, and I choose the nodes of the edge one component and then I select both components. I use re mesh option and create. I wanted to know if this method is good? One thing I have noticed is that after creating the RBODY, my mesh gets changed and lot of elements fail because of the re mesh option I use. I also get like 1000's of warnings after I run my model on RADIOSS (attached picture). I wanted to know whether the technique I am using is a good practice or is there is any better way for the same.

Thank you,

Datta

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Altair Forum User

Hi Datta,

It is not recommended to set a node of the mesh as the master node of a rigid body as it can result in an incompatibility. Instead of selecting type as rigid, you can select spring and can model spot weld.

Please watch this webinar which shows rigids and connectors modelling in RADIOSS: https://www.youtube.com/watch?v=kYWyjCfSnkU&list=PL1u26y75SCrA_BOCLaSewVCNY7xRvCTnA&index=3 . The parameters required for modelling and its importance are covered in this webinar.

Altair Forum User

Thank you for the info George. I watched the video, its little confusing. Do you have any pdf where similar cases like this has been done? I also want to know what happens if I do not use remesh option while doing the connectors and instead use project and find nodes? Will it cause any difference?

Altair Forum User

George, could you please share some tutorial for this?

Altair Forum User

Hi Datta,

A document is shared which contains all aspects related to connectors and also a tutorial is attached.

Unable to find an attachment - read this blog

Altair Forum User

Hello George,

If I use Spring to model Rigids, what should the property be? And should it be Part Card for the component where the springs are?

Altair Forum User

Hi Datta,

If you are using spring elements, you can assign with /PROP/TYPE13 ( Beam Type Spring Property Set) and assign with high stiffness values in the card so that the spring elements will not elongate.

It should be a PART card and for spring elements only property will be assigned.

Altair Forum User

Thank you for the reply George, but when I use PROP/TYPE13 I am very confused about the parameters I have to use. Please could you tell me what parameters I should input?

Altair Forum User

Hi Datta,

Provide a negligible mass(like, 1e-5 assuming mass is in tonnes) to the spring element. And add very high stiffness (like 1e5)in all directions (K_Tensn, K_ShrY, K_ShrZ, K_Tor, K_FlxY, K_FlxZ) of the spring so that it will highly stiff to resist any elongation. Meanwhile, please refer the Help Menu for /PROP/TYPE13. All these parameters are defined there and an example card is also provided for better understanding.