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Testing 1,2,3.

Synchronizing the Virtual and the Real. "Testing has become the bottleneck for CAE," says Doug Marinaro, vice president, Software and Consulting, at MTS Systems Corp. (Minneapolis, MN). One big reason for this: "Testing data is not in a form that can be readily absorbed by CAE." According to Marinaro, current attempts to calibrate CAE simulations with physical test data are "low-resolution, expensive and narrowly applied." Consequently, calibration is time-consuming and requires advanced engineers to do the job--and they may have their own approaches to the task. The need for a tool that is both quick and standard is apparent.

MTS borrows the Jungian" to describe its approach to bringing the real and virtual test worlds together and has four principles behind it:

1.Correlation--continuous calibration between CAE and physical data

2. Access--ubiquitous data management

3. Speed--test process automation

4. Communication--seamless communication between CAE and physical data

The synchronicity architecture consists of a software layer that connects both the pre- and post-testing calculation processes of the physical and virtual procedures, then calibrates them so the results have a direct correlation. MTS has two new products that use this architecture to achieve specific goals.

* Safedesign Insight. A CAE postprocessor for Madymo, Dyna and Nastran that allows engineers to overlay CAE simulations over high-speed video of physical crash tests so variances can be seen immediately (current software only allows for side-by-side comparisons). Test set-ups are visually validated prior to running to ensure that testing time is not wasted because key adjustments were neglected. It also automatically correlates between CAE models and actual test results, and is designed for use with barrier, sled and component tests.

* Safepass 201. This toolset is directed at helping companies achieve FMVSS 201 certification by automating the calculation of impact points and displaying both the test and CAE results on the vehicle geometry for design validation. Joe Strelow, MTS's Safety and Engineering Software product manager, says that over 30 impact points have to be analyzed at least 20 times per vehicle program, and this can take 8 hours per point using current methods. He says Safepass 201's automatic calculation function can do the impact point calculations in less than 30 minutes (reducing total time per analysis to about 4 hours, including model preparation), and that the tool will automatically adjust) for design changes.

Wireless Probe. Leica Geosystems (Norcross, GA) has a new armless and wireless portable T-Probe for its LTD700/ LTD800 laser trackers. The probe can maintain a 0.1-mm length accuracy over the full length of a car and allows deep parts and tools to be measured with six degrees of freedom.

Emissions Tester in Your Trunk. Horiba's OBS-1000 on-board emissions measurement system fits in the trunk of a test vehicle, which is handy when testing has to include the effects of traffic and environmental conditions on exhaust emissions. The system can continuously measure CO, C[O.sub.2], HC, and NOx and calculate the weight of exhaust gas generated and fuel consumed per unit of distance. A built-in GPS receiver and a network of sensors track vehicle position, velocity and engine revolution data which is fed into a laptop PC with data logging software. The system can be used to test vehicles using alternative fuels like LPG and CNG as well as with gasoline--and diesel-powered vehicles.

Humidity on Demand. GE General Eastern Instruments, Inc.'s (Wilmington, MA) Humilab is designed for calibrating humidity sensors, transmitters and instruments. It employs a chilled mirror of polished rhodium as the primary humidity instrument and infrared optics to control thermoelectric cooling and heating. It uses a time-proportioned divided flow technique to attain a 0.2% RH relative humidity stability. The stainless steel chamber has a 644 [in.sup.3] volume--enough space for several instruments to be calibrated simultaneously.

Simulating Software. Let's say you are a controls engineer tasked with writing the software code that will control an active suspension system. You want to try out several different algorithms to see which one will give the suspension the best performance, but when you ask the mechanical engineer who is designing the suspension components to run your code through his FEA program, he politely asks you to come back, say, next Tuesday. You need a program that can tell you the constraints on the suspension's movement without giving you unnecessary data like material failure limits. Which is where SimMechanics comes in, as it allows engineers who primarily deal with designing software to quickly simulate mechanical systems so they can run tests and modify their control algorithms before ever having to induce a mechanical engineer to run a full system simulation.

Scott Lehman, automotive marketing manager at The MathWorks Inc. (Natick, MA), producer of SimMechanics, says that the product is part of a move to give engineers tools with different levels of fidelity more suited to specific needs, and that don't require advanced software degrees to operate. "Five years ago the people who were doing virtual testing were in research labs and today it is becoming the mainstream way for production programs to develop things," he says. That change has come about largely because tools have become more user-friendly. Lehman explains, "In the past, simulations were done in Fortran or C, so to do it you had to become a software engineer in addition to, say, a controls engineer. Now it is done in a graphical way." The benefits to development programs are clear. Not only does the controls engineer not have to wait until next Tuesday to run his simulation, but when he eventually goes to the mechanical engineer he can give him high quality algorithms that should help speed the program along.

Along the same lines, The MathWorks' Model-Based Calibration Toolbox allows engineers tasked with developing engine management algorithms to run simulations that refine trade-offs until the desired performance is reached. The big advantage to using this toolbox is that the engine to be simulated only needs to be run once on a dynamometer for characterization. The rest of the work can be done at the desktop, which saves a lot of expensive dyno time. Lehman says that he expects the demand for the toolbox to grow significantly as automakers develop more complex hybrid powertrains and struggle to meet ever stricter emissions standards.

Hydrogen Leak Detector. The H2000 from Sensitor Technologies (Billerica, MA) uses hydrogen as a tracer gas (in a 5% hydrogen, 95% nitrogen mixture) to detect leaks. The compact unit is entirely electronic, so there are no pumps, valves or vacuums to maintain. It can identify leaks independent of temperature and has a dynamic background compensation function that reduces background interference.
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Title Annotation:Equipment & Applications
Author:Whitfield, Kermit
Publication:Automotive Design & Production
Geographic Code:1USA
Date:Dec 1, 2003
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