Okay, then the diaphram should have an OD that is equal to the ID of the inner cylinder so there is no overlap. Then use the plane on each side of the diaphram to slide the cylinders. In DesignModeler, put all the solid bodies into a single part by selecting them in the outline then right click and select Form New Part.  This will create Shared Topology and the mesh on each solid will be connected to its neighbors by sharing nodes.  You can also try to use a Linear Pattern to replicate the structure from the first copy down the line.