Decomposing associations (SysML)
Decomposition of one-to-one Associations is achieved through Association Blocks. On a Block Definition Diagram, an Association Block is a Block that is linked to a one-to-one Association through an Association Block Link. You can then decompose the one-to-one Association by creating an Internal Block Diagram for the Association Block.
For an example of Association decomposition, click here
To create a one-to-one association:
1. On the Block Definition Diagram's tab, click the 
Association button.
Association button.2. Click the start Block, and then click the end Block.
To link a block to a one-to-one association:
1. On the Block Definition Diagram's tab, click the 
Association Link button.
Association Link button.2. Click the one-to-one Association, and then click the Block that is to be an Association Block.
To populate missing association links on a block definition diagram:
Right-click the background of the diagram, and select > > .
To create an internal block diagram for an association block:
1. Right-click the Association Block, and select > > .
2. Type the name of the Internal Block Diagram, and then press the Enter key.
Note that you can open a Block's Internal Block Diagrams by right-clicking the Block, pointing to Open, and then clicking the appropriate command for the diagram you want to open.
To populate an internal block diagram with participant properties:
Right-click inside the diagram background or owning Block if shown, and select > > .