About SDI
Simulation Dynamics, Inc.: building models since 1990
We are a simulation and analytics firm. We build models of lines, plants and supply chains, and the apps that let your own people run them. We are privately held and 100% American owned.
Trusted by 300+ organizations since the early 1990s
From bulk flow simulation to decision apps
Andy Siprelle left an industrial engineering job at ALCOA in 1990 to start SDI. That year he created bulk flow simulation, a rate-based way to model high-speed and bulk lines that later became known as discrete rate simulation.
SDI adopted Extend (now ExtendSim®) early and worked closely with its makers at Imagine That. With his partner David Parsons, Andy built the SDI Industry libraries, a database library and Supply Chain Builder, and SDI completed hundreds of projects on lines, plants and supply chains. Andy also wrote the original ExtendSim training course.
In the 2000s, clients who owned Siemens Plant Simulation asked us to work in it. They paid for our training, and more than 50 projects followed.
Then came VINLogic. A logistics model that took 6 hours to run was rebuilt in .NET to run in 20 minutes, and its client used it for more than 10 years. It taught us that the lasting value is in apps built on models. Today apps we built are used by more than 15,000 people a day.
- 1990
SDI founded
Andy Siprelle creates bulk flow simulation, later called discrete rate.
- 1995
First WSC paper
"Modeling a Bulk Manufacturing System Using Extend," Siprelle and Parsons. All papers.
- 1990s
ExtendSim libraries
SDI Industry, the database library and Supply Chain Builder. The first official ExtendSim training.
- 2000s
Plant Simulation
At clients' request. 50+ projects over the next 15 years.
- 2000s
VINLogic
6 hours to 20 minutes in .NET, and the start of our model-based apps.
- 2010s
Apps at scale
A production-loss app for a global CPG manufacturer, and the development team to run it.
- 2024
ChiAha spinoff
Product work moves to ChiAha. SDI stays focused on client projects.
We don't sell software. We pick the tool that fits the question, or build the tool in house.
Some problems need a fast, rate-based model of a 1,200-bottle-a-minute line. Others need 3D animation that a plant team can walk through, or an optimizer wrapped in an app a planner runs every Monday. We have built all of these, in whatever your team already uses or in what fits best.
Three tools we know from the inside:
- ExtendSim: 35+ years of project work, plus the libraries we built for it, including the first discrete rate (bulk flow) engine.
- Plant Simulation: 15+ years and more than 50 projects, led by engineers who spent their careers in consumer packaged goods plants.
- ReliaSim: the third generation of our discrete rate method, for line reliability and OEE, validated within 1% of measured OEE.
We also build and curate simulation libraries inside these tools, so your own modelers start from tested equipment blocks. When a model outgrows the tool, we rebuild it in .NET, F# or C# so it runs in minutes and your planners can use it without us.
Why we spun off ChiAha in 2024
Running a services firm and a products company under one roof is hard to do well. So products went to ChiAha, and SDI kept consulting.
100% American owned
Privately held and independent for 35+ years, with direct access to the people who run the company.
The people of SDI
Engineers who spent careers in consumer packaged goods plants, alongside operations researchers, data scientists and .NET developers.
Andy Siprelle · Owner and founder
Industrial engineer (Virginia Tech) who founded SDI in 1990 and created discrete rate simulation. He has led every move from ExtendSim to Plant Simulation to .NET apps.
Amber Siprelle · ChiAha co-founder and SDI managing director
Operations researcher (MS, University of Tennessee) in simulation and optimization since 1996. She led SDI's ExtendSim training for many years.
Three groups, one team
Simulation Group
ExtendSim, Plant Simulation and ReliaSim® models of lines, plants and supply chains, plus the libraries behind them.
Enterprise Group
.NET and full-stack developers who turn models into applications people use every day.
Innovation Group
Data scientists and F# developers who prove new ideas on your stack before they scale.
People who built SDI
David Parsons, co-founder (retired), co-created SDI's ExtendSim database library and Supply Chain Builder, and co-wrote our first WSC paper. He retired in 2010 and worked with us until 2018. His books.
Michael Denzien, our first CTO (retired 2022), brought C# to SDI, which made the .NET rebuild of VINLogic and every app since possible.
Tell us your problem
What would happen if you changed it?
Describe the decision in front of you. We'll tell you whether a model can answer it, and what it would take.
- A straight answer on whether simulation is the right tool
- Which tool fits, even if it isn't one we use every day
- A rough scope and timeline, before any commitment