Modeling Sustainment Dynamics
March 2014 • Presentation
Sarah Sheard, Andrew P. Moore, Robert Ferguson
This presentation overviews a systems dynamics simulation model that describes influences of multiple variables on the sustainment phase of a system.
Software Engineering Institute
This presentation was given at the 12th Annual Conference on Systems Engineering Research (CSER 2014) at Redondo Beach, CA, March 21, 2014.
While many life-cycle phases have well-defined processes, the sustainment phase does not. Too many organizations are involved, and activities have very different cycle times. The dynamics of the situation usually overwhelm any linearly defined process descriptions. To describe the growing cost of software sustainment, the SEI has modeled the dynamic activities occurring on a program in the sustainment phase. This presentation shows the resulting systems dynamics simulation model that describes influences of multiple variables on each other, showing how an impulse function-such as a threat change that requires upgrade to operational equipment, or a reduction in staff due to sequestration-causes changes that propagate through the system. Creating this simulation involved describing (a) stakeholders, (b) the sustainment system boundary, (c) a causal-loop diagram of variables and interactions, (d) equations that describe the interactions mathematically, (e) simulation of equilibrium with notional variable values, (f) pulses that change the dynamics, and (g) system response. Calibrating this notional model requires describing realistic sustainment variables and collaborating with sustainment organizations to obtain data.