System Dynamics Structure

System Dynamics Structure

A very simple structure of seven to ten part types can illuminate any system.

Canvas 1 Layer 1 Refresh Button Circle-Plus Button Circle-Minus Button Controller Stock Control Valve Source (boundary) Sink (boundary) Control Relationship Flow Relationship Circle-X Button Circle-X Button Control Direction Reinforcing Loop Balancing Loop Circle-Plus Button Circle-Plus Button Circle-X Button Refresh Button B R

**CONTEXT:** Fully developed system dynamics models can seem overwhelming in their detail. It is comforting to realize how few part types there are to deal with when making or interpreting system dynamics models.

**PROBLEM:**

**When confronted with complex models people may think that learning to make models will be too hard.**

**Forces:**

**Recognize how simple the basic building blocks are. Make a few models with the basic building blocks.**

**Actions:**

* Read the definitions of each of these 10 parts. * With paper and pencil, sketch out a few models of your own using these parts. * Start with stocks. * Add [[flows relationship]s with control valves. * Add a few control relationships between stocks and control valves. * Add a controller. * Add a control relationship from the controller to a control valve. * Add control directions. Add balancing loop and or reinforcing loop designators. * Add source (boundary) and sink (boundary).

NOTES:

Probably should add "Feedback Loop" to the diagram.