ATV Digital Prototype for Structural Durability Task Group

Unconfirmed Minutes - April 19, 20 & 21, 1999 DaimlerChrysler - Auburn Hills, MI

Monday, April 19 - Task Group Meeting

Call to Order Raj Thakkar called the meeting to order at 1:00 p.m. The minutes from the special meeting held October 19, 1998 in Bloomington, MN were approved

Data Available via Web Site Dan Klann summarized the data that can be found at the IData/ATV page of the FD&E web site. The content includes IGES geometry, FE model Patran database, mode shape displays, the fall 1998 report-outs by Dan and the UIUC students, and over 120 photos. Each data subject directory contains zipped data files plus a "read-me" file describing the directory contents. Additional data can be submitted to Christoph Leser via E-mail or ftp. Dan and Christoph are looking for suggestions for improving the site. One suggestion was to post ATV part numbers at the site. Finding all the part numbers to help this project may not be easy, as the service manual does not provide much assistance.

FE Analysis Ideas Dan discussed possible next steps for the UIUC model. Simple loads and boundary conditions, based on rig data, could be tried first. How detailed should suspension modeling be? Perhaps loads into the frame could come from a multi-body dynamic simulation of the suspension. If bushing characteristics are to be included in the boundary conditions, bushing tests still need to be completed. Control arms and an additional $2-4K would still be needed to finish testing at the Keweenaw Research Center (KRC). At that point, the overall issue of funding was discussed among the group. It was estimated that at least $10-15K would be needed to complete the tasks agreed upon thus far (bushing tests, tire tests, additional frames and other parts, etc.).

Fatigue 2000 Conference Ralph Stephens proposed the idea of presenting a paper on the digital prototype project at the Fatigue 2000 Conference, sponsored by the Engineering Integrity Society (EIS), to be held 10-12 April 2000 at Robinson College, Cambridge, UK. Attendees of previous EIS-sponsored conferences noted that these meetings have a truly international flavor and mostly industrial, rather than academic, representation. More information about Fatigue 2000 and other EIS conferences and activities can be found at their web site. The consensus of the group was that there is probably not enough time to prepare a paper for Fatigue 2000, and such a paper would be unusual in that it would be about a work in progress that is rather far from completion. The group will remain open to opportunities to present a paper on this project at later conferences (e.g. SAE 2001?).

Tire Testing Will Mars described test requirements and outputs. The description included a diagram explaining forces, moments, slip angles, camber angles, etc. To complete all iterations of load, inclination angle, and slip angle (some of which wear the treads), 5 front and 5 rear tires are required. Testing may be more cost-effective if performed at Cooper-Avon in the UK than at Smithers Scientific Services (Cooper-US's most common source for these tests). Cooper will soon use one of their production applications for correlation between Avon results and Smithers results. If the correlation results are favorable, that will build more confidence in working with Avon. Avon's test fixturing would require a rim adaptation at an estimated cost of $2600 and lead-time of one month after receipt of the work authorization P.O. The five sets of tires still need to be procured as well. At this point in the discussion, the funding issue came up again. A few attendees wanted to see if other machine shops could do the adaptation for a lower cost. NOTE: discussion during the divisional planning session on Wednesday the 21st led to exploring an opportunity for MTS to help out with tire testing. For more information, please refer to that session's minutes, or contact Will Mars or Kelly Donaldson.

Bushing Tests at KRC Dennis Popma discussed shock bushing test results. Frequency-dependent (0-500 Hz) stiffness testing was conducted in the radial direction for the front and rear shock bushings; testing of conical stiffness of the front shock bushings is still to come. Test displacement was 0.1 mm peak-to-peak for the rear shock bushings, 0.25 for the front. Dennis showed graphs of stiffness vs. frequency and provided damping coefficient data. The bushings were found to be quite stiff, noted as an order of magnitude stiffer than typical values for cars. Before we conclude that we may be able to ignore bushings for predictive work, we should get test results for the control arm bushings. Again, the funding issue came up, this time specifically for front shock bushing conical testing and for all testing of control arm bushings. NOTE: after this meeting, concern was expressed that the shock bushing tests may need to be run to higher displacements than KRC has done thus far.

Dynamic Modeling New Ideas Ric Mousseau proposed using Carsim for a rigid-body model. The model should generate vehicle responses and component loads, should be easy to use, should be freely distributed to all interested participants, and can be run in software developed by UMTRI and MSC (Mechanical Simulation Corporation). An educational version of Carsim is available to interested parties. More information can be found at their web site. Carsim is capable of producing the same types of results for these rigid-body analyses as DADS. Ric intends to do no more ADAMS modeling for this project, but any other participants are welcome to continue. Flexible-body ADAMS modeling may be continued for the sake of integration with CCAD's fatigue analysis efforts. MDI (represented at this meeting by Doug Peterson) and CCAD (represented by K. K. Choi) may work on this together.

This concluded the presentations. Raj Thakkar asked all presenters to give him copies of their presentations.

There was one last discussion about funding. Darrell Socie is pursuing a university-centered, multi-company, 3+year commitment for ATV/digital prototype activities. Project funding would be around $50K per year. All interested parties should contact Darrell, Tom Cordes, or Raj Thakkar. Obviously, shorter-term contributions of any practical amount to complete the tasks described at this meeting are also welcome.

The final topic of the meeting was future planning. Compilation of action items and volunteers coming out of both this special meeting and the April 21st divisional planning session can be found in the minutes of the divisional planning session.

The meeting was concluded at approximately 4:30 p.m.