Kinematic Constraints

Altair Forum User

Hello everyone,

 

i need to set up a dynamic FEM Simulation in RADIOSS with several bodies. It's a mix of rigid and FE bodies. For jointing them, i want to use kinematic constraints but for me it's hard to find out how these kinematic constraints are set up correctly.

Is there a tutorial how to set up kinematic constraints in HyperMesh (with RADIOSS)? I'm also very glad for some advices.

 

Thanks.

Altair Forum User

Hi Lorenz,

 

You can constraint the bodies using BCs manager which is available in Utility browser.

 

Please refer to the RADIOSS tutorials for more information

 

http://www.altairhyperworks.com/hwhelp/Altair/hw13.0/help/hwsolvers/hwsolvers.htm?rd3500.htm

Altair Forum User

Hi Prakash Pagadala,

 

thanks for answering so fast. My Question aim more for kinematic joints to connect several bodies. Therefore i can't find any tutorial or example or even some advices

Altair Forum User

Hi LoHo,

 

What type of joint are you trying to model?

 

Maybe you should look at PROP/KJOINT (prop/type33) in RADIOSS.

Altair Forum User

Hi Prakash Pagadala,

 

i've tried already these PROP/KJOINT (type33). This is exactly what i meant. I need to know how these prop work correctly and how they are defined.

Altair Forum User

Please refer to help for more information on Kinematic joints.

<?xml version="1.0" encoding="UTF-8"?>

Altair Forum User

Thanks, but i already read this help section. Any other advices?

Altair Forum User

LoHo,

 

Say I need a translational joint,

 

define a spring to represent translational joint with type 33 property. It needs 2 skews to be defined for end A and end B of the spring element.

Altair Forum User

Ok:

1. Create SPRING2N

2. Create /PROP/KJOINT type33 and select the desired type of joint

3. Relate SPRING2N to FE-Mesh or rigids

4. Create SKEWs for each point of the SPRING2N

5. Define /PROP/KJOINT with the SKEWs

6. Assign /PROP/KJOINT to SPRING2N

 

I'll try this and send a reply. Thanks, Prakash Pagadala.

Altair Forum User

Hallo everybody,

I tried to model a sperical joint. I do the steps 1 to 6 mentioned above. But the result is, that many of my shell elements are deleted. Could anyone tell me where is my mistake?

Altair Forum User

Could please anyone help me or give me an other advise how to model a hinge?

Altair Forum User

Hi,

 

Please refer to Cylindrical joint in RADIOSS help

<?xml version="1.0" encoding="UTF-8"?>

Altair Forum User

Hi Prakash,

thank you for the advise. I already looked at the Cylindrical joint in the radioss help, but this is not exactly what I want. I need only a rotation around one axis in space. The cylindrical joint has in addition a translational dof along one axis. So the CJ is not useful for me.

 

F.M.

Altair Forum User

Hi Fabian,

 

In PROP/KJOINT, change the type to 1 

<?xml version="1.0" encoding="UTF-8"?>

Simon Križnik

Hi,

 

can someone upload a file where KJOINT is used (for example with revolute joint)?

 

I tried to follow the steps by LoHo, but I struggle to understand step 3. Relate SPRING2N to FE-Mesh or rigids

Altair Forum User

Hi Ivan,

I recommend you to define using /PROP/TYPE45 spring joint, which describes the joint type spring between two rigid bodies.

Simon Križnik

Thanks for the tip, George. 

 

It is worth mentioning that the spring element must connect slave nodes of different rigid bodies.