Subsystems of an early model JLTV. Image courtesy of Justin Madsen’s Master’s thesis, page 36.
Some of these engineers were a part of Professor Dan Negrut’s team from the University of Wisconsin – Madison (UW-Madison). Negrut’s Machine-Ground Interaction Consortium (MaGIC) promotes computer simulation of vehicles to assess how they will act in the field under different scenarios and types of terrain.
"With computer simulation, you can test all sorts of maneuvers and change the vehicle configuration," said Negrut. "Good simulation tools let you test more scenarios cheaper and faster."
In contrast, prototype model testing of equipment like the JLTV is costly, inexact and time-consuming to perform in field tests.
Many of the simulations currently performed in industry are on the parts level; FEA, CFD, and multiphysics simulations that confirm a part will perform to its design specifications. At times, these specifications can be based on industry standards, or statistically probable loads.
However, using system level simulations like those on the JLTV, users will be able to assess how the entire vehicle will react when driving over a particular terrain. In essence, the simulation can determine the loads that the individual parts will actually experience in the field. These numbers can then be recorded and used in more realistic part-based simulations to ensure the parts will function properly when experiencing these loads.
Early model JLTV simulation sees the vehicle climbing a rocky hill with over 10,000 unique rigid bodies:
“In an ideal world, you’d be able to gauge the performance of the vehicle without having to build it,” explained Negrut. “This will allow for better designs, reduced costs and reduced design cycles because rather than waiting months to test things in the field, we can do it on a computer.”
Eventually, these simulations might even be able to predict the performance of a vehicle in scenarios that cannot easily be tested, such as a car driving through water instead of air. “It’s not yet clear to what extent we can understand certain things through computer simulation,” explained Negrut, “and we’re trying to advance the spectrum of problems for which modeling simulation is good enough.”
Other UW-Madison faculty will use experiments to validate the software created by Negrut’s team. For instance, Professor William Likos will examine how wheels move in sand to compare with the software results.
"I'm doing my best to translate my lab's research and innovations into computer tools and analysis methods that these folks can use to improve their engineering products," he added. "It's as simple as that - the merit is all theirs, and their vehicle is amazing. I hope I'll help them make it even more amazing."
Much of the software that Negrut’s team created is also available on their website. Negrut said, “We believe making it all open source is the best way to ensure this transfer of technology from us to industry, where people can take advantage of the techniques and the software that we develop as part of this project, so as to foster innovation here or elsewhere in industry.”
Members of Oshkosh have attended MaGIC meetings and presented their work there. The cooperation between the organizations was vital to the DOD deal. Other industry MaGIC partners include BAE Systems, Caterpillar, Harley-Davidson, John Deere, P&H Mining and Trek Bicycle.
Oshkosh also recently hired Justin Madsen who recently completed his post-doctorate with Negrut. Negrut mentions that hiring academic experts is another great example of transferring knowledge to industry.
Some of Madsen’s simulations of an early model JLTV vehicle can be seen below:
Early model JLTV Simulated in MSC Adams and FTire to model rough terrain at high speed:
Early model JLTV Simulated in MSC Adams and FTire to model wide turns:
Early model JLTV Simulated in MSC Adams and FTire to model rolling hills: