These days, Amelia and her passengers would be a lot safer, thanks to the laboratory’s real-time crash dynamics analysis. They’d also be a lot more comfortable. Focusing on conditions in the cockpit and the passenger cabin, the group analyzes aircraft engineering and manufacturing processes, ranging from pilot seat placement to how far a passenger has to reach to turn on the overhead light.
From 1-D to 3-D
Virtual reality can predict how passengers might behave in a plane, such as putting luggage away or pulling down the food tray, or visualize several thousands of components of a large plane in real-scale. With seating for 25 and 3-D glasses for viewing at the Virtual Reality Center (VRC), visitors can be the pilot, the passenger or the assembler. Engineering data can be transferred from other computers, making the VRC into a virtual wind tunnel or a crash lab.
Amelia Earhart's plane cruises the Pacific -- 75 years after it disappeared.
In the case of the Earhart aircraft, engineers used primary data sources to recreate the aircraft ditching and test the likely hypotheses of Amelia’s disappearance.
NIAR took on the research after a request from National Geographic, which was producing a documentary analyzing Earhart’s disappearance. NIAR began with paper drawings of the plane and converted the specifications to 3-D, overlaying information gleaned from her departure fuel volume, cabin conditions, historic flight manuals, weight specifications, and pilot procedures, as well as sea conditions logged by a nearby Navy ship.
The lab was able to model fluids and structure to get the accelerations and translate the data into bio-mechanic software. Using a crash dummy simulating Amelia Earhart and rendered drawings of the plane’s interior, the occupant simulation demonstrated the impact of the crash on Earhart’s physical person.
This process is essentially the same for any of today’s scenarios.
Crashing without casualties
NIAR is currently performing studies to provide information to the Federal Transit Authority (FTA) on the performance of mass transit buses in crashes. For this study, the VRC is being used to graphically describe crash effects, so they must import data from many sources to begin creating the virtual reality scenario.
“EnSight Gold lets us utilize data from a variety of native formats, such as LSDyna, MSC/Nastran, MSC/Dytran, Abaqus, Fluent, and so on. We have a lot of versatility that streamlines our process,” says Fernando Toledo, VRC Manager.
Each variable affects the distance traveled and the survivability. With NIAR’s advanced techniques, the extensive analysis examines the dimensions created by individual circumstances – from every angle: one pilot, measured from the top, side, and head Center of Gravity (CG) strike area, or path; the cockpit conditions – including primary data photographs from archival sources; and body measurements, such as head and lumbar loads; thorax and pelvic accelerations, neck forces and moments, and head paths.
Any scenarios, as Amelia Earhart’s, might include aircraft cabin acceleration, aircraft CG rotation (pitch, yaw, and roll axis), aircraft CG displacement, and aircraft CG velocity. From this baseline, the lab uses timelines to determine aircraft kinematics and can calculate summary injury values. Emergency room, anyone?
Testing, analysis, and disaster prevention
The lab uses the data not only to create a virtual reality model visualization, but also to then compare the test to the original data on CEI’s EnSight Gold with digital analysis. A complete testing process can take anywhere from one to six months or more. Toledo prefers EnSight Gold software because it enables a PC-based cluster for processing that he believes is 12 times faster than other leading software.
To create the simulations, the lab relies on immersion and interaction techniques in its 1,842 square foot visualization room. With its recent modernization, the lab is able to create models with semi-immersion – where virtual objects are overlaid on a real environment or real objects are overlaid on a virtual environment.
As a research institute, the lab uses virtual inspections to conduct design, research, testing and certification, ranging from mass transit evaluations, i.e., analyzing accidents and determining what happened and why, to FAA certification of aircraft interiors to predict failures and prevent disasters.
Unlimited information from every angle
Virtual reality shortens the development cycle, speeds up design – and saves lives. Nevertheless, it takes thousands of pages of reports to visualize the scenario. Successful virtual reality involves input from CAD, engineering, and manufacturing. EnSight Gold makes it possible to have large models in the virtual reality center that are prohibitive on a PC. In the end, virtual reality can be much less expensive than physical testing. Hundreds more tests can be conducted, and it isn’t necessary to build prototypes.
Virtual reality also saves time in the long run over physical tests. Imagine spending months creating a physical scenario, only to find that you forgot to do something or didn’t take all factors into consideration. You’d have to start all over again. Back to the drawing board.
Virtual reality provides a view from every angle – as well as almost unlimited information if created correctly. In any case, modifying the test to include additional information does not involve re-starting from step one.
EnLiten, CEI’s free 3D geometry viewer, is used to visualize the data. On-site visualization is done primarily with an active stereo flat screen projector-based system, where research scientists and graduate students can collaborate and see their LS-Dyna results in a semi-immersive environment. EnLiten runs on a dual-channel PC with resolution of 2368x1024@100s and it takes fewer computer resources to load the data with similar visual performance of EnSight Gold. Because EnLiten versions have backward compatibility, older data can be visualized without recreating simulations.
Collaboration, communication, and cooperation
Time and money considerations extend beyond creating the models themselves to sharing the information and getting quicker decisions. Collaboration between sites without travel scheduling and expense is a real benefit, but the NIAR model also allows remote participation by key teams that are not fully equipped to run the complex scenarios.
LS_DYNA side impact analysis project with the FTA. A Chevy truck is traveling at 30mph and hits a bus, also traveling at 30 mph, at a 90 degree angle.
“With virtual reality, we can share the model with multiple locations simultaneously, and people with PCs can participate fully,” says Gerardo Olivares, a NIAR research scientist. “All the heavy processing takes place at the virtual reality center, so our partners and associates are only seeing images because we’re transmitting video signal. Stakeholders can discuss the information and make decisions from anywhere.”
EnLiten is also used to share results with other locations, especially when portability is an issue. Toledo adds, “While EnSight Gold is a good engineering authoring tool, EnLiten enables individuals without CAE training to visualize complex crash simulations.”
Thanks to NIAR, the FTA is making mass transit buses a safer way to get from place to place, and we can also be sure that we won’t have to call a chiropractor after reaching for the overhead light on that flight to Cincinnati.