assembly hex global stiffness matrix

Altair Forum User

Hello, everyone

 

I have a model with hex elements, like below(model.png) :

 

I want to get this model's global stiffness matrix.  for element stiffness matrix, I use the local coordinate like the coordinate.png show:

 

I ouput the ( node id, node coordinate, element id, node list of element) for get the global stiffness matrix. But it seems the local coordinate or the order of the node list of each element of hypermesh is different from mine. I don't know how to reorder the node list which I get from hypermesh.

 

The node list order Which I get from hypermesh is show in nodeListHypermesh.png. It seems is anti-clockwise.

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

 

Thank you so much for your time. Any advice will be appreciated. (^_^)

 

 

tinh

it  is global axis, not local

and the ids are global ids, local ids are always 12345678, it means nodes #4 on png image is local id 2

Altair Forum User

@tinh  Thanks a lot for your time.

 

Is this means, I can use the order directly?  Just input the order's node coordinate, then calculate the element stiffness matrix. And put the correspond DOF into global stiffness matrix?

But I have tried that. It seems not work. Might you give me more detail? 

 

Thanks 

Donggua

tinh

yes, it is. but I don't know more detail

Altair Forum User

@tinh Thanks a lot for your advice.

 

Yes, what you say is right. Before this I mess up the DOF of global matrix. Now it can work. Thank you indeed. (^_^)