Learning Forum

[mwhitte6]

I am attempting to create a 27-node solid 3D user-defined element with the LS-Dyna object code. However, it appears to me that the object code is hard coded in many, many places for 8-node solid elements. For example in the dyn21usld.f file and then in the usrsld() subroutine, the main subroutine the calls the user-defined element subroutine, declares the bmtrx variable as:

common/bel7loc/bmtrx(nlq,3,3,8*(3+NXDOFUE))

where (based on my interpretation):

nlq - number of elements in current block

3,3 - matrix of shape function derivatives

8*(3+NXDOFUE) - number of nodes,8, times the number of degrees of freedom per node

This matrix is hard coded in many places throughout the dyn21usld.f file. Also, this is just one example of the hard coded nature of an 8-noded element there are also other variables such as the bvec array, as well as, do-loops that appear to be hard-coded for 8-nodes. 

Q1: Can user-defined elements be developed with more than 8-nodes per element? 

Q2: Does that require tracing through all the places where an 8-node element is assumed? 

Q3: Is there an easier way to develop a user-defined element with more than 8-nodes rather than finding all the places where it is hard-coded?

Q4: How will the rest of the program know how many nodes are being used for the element? 

Q5: Am I correctly interpreting that at least some of the variables and do-loops are hard-coded for 8-node solid elements?