Define Gun Tube Springs

When the lumped model is automatically generated for the projectile, springs are defined. For the gun tube the supports which are entered as springs have to be hand entered.

Upon completion of the generation of nodes and/or elements for the gun tube, the gun tube supports are entered as springs. There should always be three springs defined; an aft lateral spring, a forward lateral spring, and an axial or recoil spring. The two lateral springs can have spring stiffness values in two directions where as the recoil spring will have a spring stiffness value in only one direction. Even though the forward lateral spring and the recoil spring are defined at the same node, they must be separate lines in the spring definition table.

For this analysis, the gun tube support springs should be entered as shown in the table below.

One additional piece of information required is the node id upon which any axial loading will be applied. For this analysis, it is node number 2.

All of the supports are entered at the bottom of the Nodes/Springs tab. The completed information is shown below.