Error when creating an element type COMBIN14 using pymapdl

Question

I'm trying to create a mass-spring system attached to a plate with element type COMBIN14 for the spring and MASS21 for the mass. I have created the nodes needed to attach the mass and the spring. I have used this command to create the element type COMBIN14:

mapdl.et(2)
mapdl.real(2)

for j in range(1, 10):
    mapdl.e(node_number_i[j-1], node_number_j[j-1])

But when i run this command i am getting the following error:

*** ERROR *** CP = 15.156 TIME= 11:38:07
Element 1001 does not have all of its required nodes defined. The E
command is aborted.
*** ERROR

Could anyone tell me what is the problem here?

I have checked the vectors, node_number_i and node_number_j, the node number listed are valid and correct.

Answer 1

I suppose that you selected the wrong element type for creating COMBIN14 elements with two nodes. I was able to reproduce this problem by using the following code:

...
/PREP7
N,1,0,0,0       ! create two nodes
N,2,1,0,0
ET,1,SHELL181   ! define element type 181, which needs 4 nodes
ET,2,COMBIN14   ! define spring element, which needs 2 nodes
E,1,2           ! results in an error, because 4 nodes are needed
...

To resolve this problem make sure that you have selected the proper element type by using TYPE (in my example use TYPE,2). In PyANSYS the command looks like Mapdl.type(2). Here is the working code:

...
/PREP7
N,1,0,0,0       ! create two nodes
N,2,1,0,0
ET,1,SHELL181   ! define element type 181, which needs 4 nodes
ET,2,COMBIN14   ! define spring element, which needs 2 nodes
TYPE,2
E,1,2           ! create spring element
...

Just rewrite it to PyANSYS and it should work properly.