As far as I know, there are two ways to simulate the combined unit. One way is to connect two points into a line and then give the combination properties. There is also a common one, that is, after the grid of structural units, choose two points where you want to arrange springs and connect them directly to make a unit. The command stream format is:
Type, 1
Real number, 1
e， 1，2
The spring unit has been established.
Combine14 is very simple and includes two parameters: spring and damping. It is clear from the help document that the parameters should be selected according to the actual situation. Combin40 is powerful and can be used for more complex nonlinear problems.