CIMdata PLM Industry Summary Online Archive
16 January 2007
Implementation Investments
LMS Test.Lab Helps DaimlerChrysler Buses Ensure Greater Passenger Comfort in New Bus Designs
LMS announced that DaimlerChrysler Buses has selected LMS Test.Lab noise and vibration systems for implementation in its vehicle development process. To strengthen its dominant market position, DaimlerChrysler Buses is designing the broadest range of new vehicle types in the industry to meet the unique mass transportation requirements for cities, small towns, rural areas and long distance traffic in countries worldwide. A business unit of DaimlerChrysler, DaimlerChrysler Buses is headquartered in Stuttgart, Germany, and is world market leader for buses and coaches.
LMS Test.Lab was selected to increase the efficiency of the company's NVH testing group in ensuring that strict sound emission standards are met for this growing number of vehicle models. With passenger comfort a critical differentiating factor in this competitive market, DaimlerChrysler Buses has reduced interior noise on the average by more than 6 decibels from previous levels so that today buses are much quieter than a single bus decades ago. LMS technology enables test engineers in the group to establish a highly efficient testing process in which the root cause of any noise or vibration exceeding its exacting specifications can be identified and the design quickly modified.
In the state-of-the-art testing configuration deployed by DaimlerChrysler Buses, signals from accelerometers mounted on engine, axles or chassis and microphones in the passenger compartment are monitored by either of four LMS SCADAS front-end data acquisition systems with 20 or 40 high-speed channels. Engineers at DaimlerChrysler Buses cover all standard tests to access noise and vibration amplitudes with this channel count. For more detailed studies that require measurements at additional locations in the bus, the system enjoys the inherent flexibility to easily expand the channel count to 60 by connecting LMS SCADAS units together. The system can be set up quickly to add these channels, and the scalability enables the performance of a wide range of simultaneous tests in a very short time.
The multi-channel data acquisition system is combined with the comprehensive LMS Test.Lab suite of analysis, post-processing and report generation tools in a single system for performing a wide range of test-based engineering tasks. The on-line monitoring capability in the integrated LMS Test.Lab solution is particularly valuable for DaimlerChrysler Buses. Using this feature, NVH measured data are compared with target levels and results displayed in real time as run-up, run-down, idle and open-throttle operational tests are being run in the field.
The engineering team at DaimlerChrysler Buses reported that Test.Lab's on-line monitoring using color maps, 2D diagrams immediately shows them if noise and vibration are above or below maximum reference values. In this way, they can very quickly determine if further study is required, which frequencies should be investigated and what components might be the cause of excessive vibro-acoustic levels. Making these assessments on the spot saves weeks of time compared to blind-test systems that only record raw data.
When target levels are not met, more in-depth analysis of field test data can be performed back at the DaimlerChrysler Buses local NVH office using LMS Test.Lab tools for further study. To investigate resonant frequencies of individual components, for example, LMS Test.Lab modal analysis animates mode shapes or operational deflection shapes, reveals sources of vibrations and guides engineers in determining corrective actions.
The ability to perform a wide range of vibro-acoustic tests with the integrated LMS Test.Lab solution provides DaimlerChrysler Buses with greater flexibility and saves considerable time compared to the hassle of working with separate systems. Another key feature is the automated reporting feature that saves additional time, with engineers generating test documentation in a few minutes instead of days otherwise required.
DaimlerChrysler Buses values LMS Test.Lab as the perfect partner to increase the efficiency of their NVH testing operations. Overall integration and ease of use allow their engineers to concentrate on NVH issues rather than spending precious time figuring out how to run the system. Bringing NVH passenger comfort to an outstanding level is the primary focus of NVH development at DaimlerChrysler Buses. Coupled with the expertise of DaimlerChrysler Buses NVH engineers, LMS Test.Lab is the centerpiece of this effort.
For more information on LMS Test.Lab, please visit http://www.lmsintl.com/testlab .
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