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SAE-RLDA Division Progress Meeting


Minutes for 16 April 1996

PREVIOUS MINUTES
Minutes from last meeting were posted on the FD&E web site.

RAINFLOW STANDARD FILE FORMAT
The proposed standard has been posted on the FD&E web site for review and has not received any negative comments. This proposed standard will be sent out for re-ballot.

TIME HISTORY FILE FORMATS
Dan is still waiting for a clean copy of the MTS RPC3 format but will pass out working copies to the RLDA task group to get things started.

MULTIBODY DYNAMICS
Ric Mousseau presented an update on some of the current issues being addressed by the multibody dynamics modeling project.

The model of the test stand is done and test stand modifications identified. Currently working on reduced stiffness bushings. Testing is ready to start.

PRESENTATION
Gary Marquis presented an update on the status of the ATV project at the Uof I and talked about expectations in the cumulative exceedance distributions from repeated runs over a given course. For more information contact Darrell Socie.

Minutes for 17 April 1996

In attendance: D. Morrow, R. Thompson, R. Mousseau, Z. Bai, A. Page, R. Lenzen. T. Carlier, C. Sieck. L. Turley, R. Hartline, Y. Chen, J. Oian

RAINFLOW DATA FORMAT
There was a discussion about changing the file format to a generic file format with keyword header information that would apply to all types of files, not just Rainflow. It was eventually decided that the Rainflow data format would be re-balloted as is and that the definitions used for time histories would start to address the generic format issues.

TIME HISTORY DATA FILE FORMATS
A discussion of already existing generic file formats followed, and Ric agreed to track down the ERD data format. Charlie said he would report on the NCSA format at the next meeting. Copies of the MTS RPC3 format were passed out to be reviewed before next meeting.

MULTIBODY DYNAMICS
Ric presented more details on the current issues being addressed by the multibody dynamics modeling project. As presented earlier, the test stand was modified by TACOM to shift the natural frequencies out of the range of interest for testing and is now operational. Reduced stiffness bushing types are being manufactured to look at the effect of bushings on suspension response. Steve Haeg is still instrumenting the control arms to measure loads at the reaction points, bushings and ball joints. A bushing model study is underway to look at which models are potentially useful for durability calculations; Ric should be able to present results from this at the next meeting.

STATISTICS IN ROAD LOAD DATA
Art led a discussion on pass-to-pass comparisons and thought that he would be able to present some analysis of his data at the next meeting. The data consist of 12 channels and 7 passes of about 40 minutes for each pass. The data were sampled at 512 Hz and decimated to 100 Hz with a filter set at 50 Hz break frequency. The data also include some short events and are thought to be generic enough to be made available to anyone. Art pointed out that the channels near the road such as spindle acceleration and displacement may have little pass-to-pass variability, but as you move away from the road inputs the pass-to-pass variability increases.

Discussions proceeded about various ways to look at pass-to-pass comparisons and resulted in more questions than answers.... Which pass is most severe?.... for which channel?.... When do we have enough data to characterize the variability?... What is needed to define the variability for any given scenario?.... How do we take a minimum of test data and project it of the life (time) needed? ... How do we characterize the variability for use in the design process, realizing that we can’t test all possible scenarios? We are looking for new ideas on how to handle these issues.

Charlie will talk about their Tech-Math software evaluation next time.

No new business was brought up and the meeting was adjourned.