Fatigue Design and Evaluation Committee 

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

Structural Analysis Division Unconfirmed Minutes

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

Tuesday, April 20, 1999 - Divisional Progress Meeting

1. October 1998 Structural Analysis Division minutes were approved as written.

2. Status of Electronic Information Exchange on ATV Components - Dan Klann from John Deere Dan gave a brief progress report on the website and geometry and analysis. More details and overheads are presented in the minutes for the ATV session from Monday (19 April). Dan suggested the FE model to start with is the Fialek-Nelson model, which is available from the web site. Dan noted that the model is based on tube OD's (not midplanes) and uses 4 node elements. It is a nice mesh overall, but a few plate normals are not consistently oriented and the control arm bushing centerlines are not collinear. Suggestions for future work include: (1) Analyses of a simple test setup; or (2) Simply download the model and explore it, develop your analysis plan, develop a list of comments, questions, etc. To progress much beyond that would require load information from simulation.

3. Design Parameters for Stress Relief Grooves in Notched Shafts - Steve Tipton from University of Tulsa Steve presented the results of a project to optimize the design of stress relief grooves in notched shafts and potentially reduce bending stress by up to 30% based on finite element analysis.

4. Statistical Fatigue Life Analysis of Notched and Welded Components using the Monte-Carlo and Contemporary Deterministic Fatigue Analysis Theories - Gregory Glinka - University of Waterloo Gregory discussed the results of fatigue analysis theories applied to ice breaker propeller blades with stresses measured during assignments in the Southern Ocean.

5. Proposed Project to Develop A Method for Predicting Fatigue Life of Crankshafts-Tony Barr-DaimlerChryslerCorp. Tony discussed a proposal for committee work on the development of a method for predicting the fatigue life of crankshafts.

Copies of the overhead material from these presentations are attached to the US Mail minutes to provide further detail.

Wednesday, April 21, 1999 - Divisional Planning Session

In the planning session, Dan Klann of John Deere first reviewed a list of proposed tasks that can be pursued from for the ATV virtual prototype project before next meeting. The plan for the next six months is as follows:

Hari Agrawal, Mary Wickham, and Zhengxian Bai will obtain the current FEA model of the ATV frame, modify if necessary, and perform a number of linear analysis using NASTRAN, such as static stiffness, normal mode analysis, stress/strain prediction, and/or direct transient response analysis. It is also mentioned that we will need to work with S/K to make sure that we will simulate the lab test, so correlation level can be established.

Dan Klann, Hari Agrawal and Zhengxian Bai will also look into performing loads prediction using the current DADS and ADAMS models with modifications or exploring a Carsim model.

Respectfully submitted by: John Hakala - SAE FD&E Structural Analysis Division Chairperson

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SAE Fatigue Design and Evaluation Committee

Fatigue Life Prediction Division Unconfirmed Minutes

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

Tuesday, April 20, 1999 - Divisional Progress Meeting

1. October 1998 Structural Analysis Division minutes were approved as written.

2. C.C. Chu opened the session by saying that some committee members had expressed some confusion about how the committee was organized. She offered one overhead, which shows the relationships between the divisions: One of the functions of the Road Loads Data Division is to provide the load data used by the Component Test and Structural Analysis Divisions. One of the functions of the Component Test Division in testing components is to provide nominal and local strain gage measurements to be used by the Fatigue Life Prediction Division (FLPD). One of the functions of the Structural Analysis Division is to provide the stress analysis of remotely loaded complex structures. The elastic stress-strain results, along with multiaxial notch correction routines can be used by the FLPD. One of the functions of the Material Properties Division is to produce material characterizations to be used in the fatigue analysis by the FLPD. As Chu presented it, the divisions support each other with results from each funneling to FLPD for stress-strain tracking and life predictions.

3. John Bonnen ("Multiaxial Fatigue Life Response of Normalized 1045 Steel Subjected to Periodic Overloads") presented an overview of part of his thesis. He also incorporated research from other U of Waterloo researchers (Conle, Dequessney, Topper, and others) in his presentation. John noted that we often do not consider low amplitude cycle damage in our fatigue calculations, but this can be in error, if field variable amplitude loading includes overloads. He showed a 4X difference in life compared to constant amplitude tests when the variable amplitude history contained a 1% strain overload. There is a parabolic relationship between crack opening stress and overload stress, whereas our constant amplitude test specimen data would lead us to believe that the relationship is linear. John proposed using "overload" strain-life data in life predictions. This data includes the effect of the overload, and John noted that it produces a curve similar to the method used by Tom Cordes for fitting properties. John showed results for bending overload followed by low amplitude torque cycling and also for bending overload followed by holding the bending load constant and applying low amplitude torque cycling. He saw a 2X drop in the endurance strain, regardless of the B/T ratio, when the histories included overloads. He saw a 5X-scatter band when plotting max shear strain or Brown-Miller vs.Life. The best parameter for correlating the data was the Fatemi-Socie-Kurath parameter. Contact John at 313-322-9127 for more details.

4. Al Conle ("Fatigue Analysis Modules and more on FD&E Web Site") noted that we have put in place several standard file formats to facilitate quick transfer of data between companies. He showed that a standard wrapper (a header and a tail) can be cut/pasted to these files to allow us to do processing of the data on the Internet. The processing can include plotting, life calculations, curve fitting, and more. This is a way to extend the value of the raw data and to set up shared material databases. Al encouraged members to look at examples he has set up on fde.uwaterloo.ca. Al can be contacted at aconle(at)ford.com.

Wednesday, April 21, 1999 - Divisional Planning Session

Web tool development and testing - There seems to be wide enough interest in the web tools Al Conle Presented in the progress meeting. To encourage more participation and development, most attendees agreed to provide Al or Chin-Chan through email (aconle(at)ford.com, cchu(at)ford.com) a material file, such as the stress-strain or strain-life curve. Any suggestion as to what fatigue analysis tools are beneficial to FD&E members is also welcome.

Respectfully submitted by: Chin-Chan Chu - SAE FD&E Fatigue Life Prediction Division Chairperson

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SAE Fatigue Design and Evaluation Committee

Component Test Division -Unconfirmed Minutes

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

Tuesday, April 20, 1999 - Divisional Progress Meeting

Raj Thakkar began the meeting at about 9:45 a.m. The minutes from the meeting held October 20, 1998 in Bloomington, MN were approved.

Raj briefly mentioned the Digital Prototype (ATV) special meeting that took place the day before. Separate minutes will be issued for that meeting. Anyone who is interested in the project data compiled thus far can visit the FD&E web site or contact Dan Klann, Christoph Leser, or Kurt Munson. One particular issue that was revisited from the ATV meeting was the level of displacement used during bushing tests. There was concern that greater displacement may be needed to characterize the highly nonlinear behavior of the bushings.

The first of the two technical presentations during the divisional progress session was from Venkata Nambori of DaimlerChrysler Jeep and Truck Engineering, on "Full Vehicle Fatigue with Real Time Road Loads: Analysis and Correlation." His co-authors were Gamal Alghanem and Ram Bhandarker, also from JTE. The FE model of the chassis structure used 32 suspension loads as input for an inertia relief solution. Batch programs were used to help speed up road load data management in dealing with such issues as spikes, polarity, schedule definition, static load inclusion, etc. The FE model was subjected to both stress analysis and fatigue prediction. Two areas of the frame were checked for correlation between analysis and testing. Although the loading is quite obviously multiaxial, only about 2% of the critical areas on the frame showed multiaxial stress behavior.

The second presentation was by Mark Pompetzki of LMS on "FEM-Based Durability Analysis of an Automotive Knuckle." The knuckle was subjected to a 3-DOF test. The loads were collected via a wheel force transducer. The analysis used quasi-static superposition and elastic "pseudo-stress." The multiaxial fatigue analysis used a critical plane approach, with damage calculated on planes in of ten-degree increments. Predicted life was within 20-25% of actual life. Several special techniques were used in the analysis, especially for saving time. "Nodal elimination" and a "rainflow projector" were among the techniques employed, the latter helping to produce a reduced load history. The reduced history was run on the full FE model, and once the critical locations were found, those were, in turn, subjected to the full history.

Copies of the overhead material from these presentations are attached to US Mail minutes to provide further detail.

Wednesday, April 21, 1999 - Divisional Planning Meeting

Paul Lubinski began the meeting at about 1:00 p.m. During Monday's Digital Prototype for Durability special meeting, several people volunteered to help out with action items required for the near future. Other ideas, items, and volunteers came forward during this planning meeting. The following is a summary of all those items and volunteers.

Finding and posting part numbers: no volunteer for this activity at this time. This issue may be somewhat alleviated if we purchase a large enough number of parts at a given time to have them on hand for anything and everything the project requires of them. Caterpillar has provided Darrell Socie with funding for 20 frames; he would like to increase that total to 30. Funding would still be required for the additional 10 frames, plus a suitable number of control arms and shocks. Al Conle will check if Ford can provide additional funding.

Continuation of FE modeling: Mark Pompetzki, Tom Cordes, and Al Conle will see what they can do. Tom will find out if someone is interested in trying the rig-input data in the model. Al will find out if anyone at Ford is interested in helping out.

Rigid body modeling: Ric Mousseau will champion performing this task in Carsim. He expects to have the work completed, with results available to the committee, by this fall's meeting.

Mass/inertial properties: at the fall 1998 meeting, continued work in this area was suggested for the frame and the combination of frame and powertrain. The topic did not come up in the spring meetings. Do we have all the data we need?

Flexible body modeling: Doug Peterson will check if MDI can contribute to continued ADAMS modeling.

Tire testing: Darrell suggested that MTS might be able to help in this task with their equipment. Special thanks goes to Ralph Stephens for finding Will Mars and Kelly Donaldson in other meeting rooms so they can get together to discuss a plan. They will specify the requirements, and Kelly will contact his colleagues regarding scheduling and other logistics.

Bushing tests: Need a decision ASAP on whether to redo radial tests with greater displacement. Need parts for control arm bushing tests? Need funding for the tests.

Modal testing: no volunteer. It is assumed we still need this work (?).

Improvements to web site: anyone with suggestions should contact Christoph Leser or Dan Klann.

If anyone is interested in volunteering wherever the project tasks require them or if there are any questions, please contact Raj Thakkar or Paul Lubinski as soon as possible.

Respectfully submitted by: Raj Thakkar and Paul Lubinski - Chairperson and Vice-Chairperson of the SAE FD&E Component Test Division.

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SAE Fatigue Design and Evaluation Committee

Material Property Division Unconfirmed Minutes

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

Tuesday, April 20, 1999 - Divisional Progress Meeting

1. The minutes from the October meeting in 1998 were approved as written.

2. Alan Kallmeyer accepts the responsibility as the composites task group leader.

3. Status of Current Activities

- Composites Task Group Progress Report I - Alan Kallmeyer reviewed the studies of the frequency and temperature effects on the fatigue of the thermoplastic composites. The fatigue life scatter is greatly reduced using the elastic energy instead of the traditional SN approach. Test results and future research plan were presented. Reference Attachment #1 in the US Mailed minutes.

- Powder Metallurgical Task Group - Fatigue Test Progress Report - Ralph Stephens reviewed the work on the FL4405 P/M steel. Additional work in the high cycle fatigue region is being planned.

3. Presentations

- Preliminary Test Results of Peened and Unpeened 2014-T6 aluminum - Russ Chernenkoff presented that the test results of the peened and unpeened 2014-T6 aluminum. The peened specimens lasted slightly longer with no appreciable difference for various coverages. The strain amplitudes and cycles to failure are shown in the table included in the US Mail paper copy of the minutes.

- The Influence of Plastic Deformation on the Elastic Modulus of Steels - Steve Tipton presented the modulus changes after cold stretch. The modulus changed up to 30%. The results are included in Attachment #2 in the US Mailed minutes.

Wednesday, April 21, 1999 - Divisional Planning Meeting

1. Current Activities - Composite Materials Group - (1) Questions on modulus changes as the fatigue damage parameter was raised. In addition, life prediction using smooth specimen simulation at the notch was discussed. Alan plans to review previous data and determine if further study is of interest. (2) There are interests in rubber materials. William Mars from Cooper Tire will give a presentation in the next meeting.

2. New Business -Modulus Change - Steve has performed additional tests and may provide an update in the next meeting. -Shot Peening 1) Residual stress of peened and unpeened specimens will be checked 2) Surface tearing and peening folds will be evaluated.

Respectfully submitted by: Ed Lu - SAE FD&E Material Property Division Chairperson

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SAE Fatigue Design and Evaluation Committee Meeting

Road Load Data Division Unconfirmed Minutes

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

Tuesday, April 20 - Divisional Progress Meeting

1. Kelly Donaldson (as a substitute for Chairman Christoph Leser and co-chair Ray Thompson, who both could not attend) moderated the meeting.

2. Darrell Socie gave a talk on obtaining information from rainflow histograms.

3. Mark Pompetzki gave a talk on cycle counting and reconstruction techniques from multi-axial rainflow histograms.

Wednesday, April 21 - Divisional Planning Meeting

Kelly Donaldson (as a substitute for Chairman Christoph Leser and co-chair Ray Thompson, who both could not attend) chaired the meeting. The minutes from the previous meeting were approved.

Rainflow standard - Mark Pompetzki suggested the established rainflow standard be expanded to handle expanded formats.

Time history format - It was officially suggested and moved in the planning meeting that we adopt the MTS RPC file format as a standard. The question was raised as to whether we need an ASCII standard.

Statistical Analysis of Data - No efforts are currently undertaken at Virginia Tech. - Darrell Socie has forwarded a copy of the thesis of Jason Roth to Christoph Leser. Any SAE member can request reprints from Christoph Leser. - Art Page pointed out that he has given Darrell Socie a 7 pass history of automotive data about 2 years ago. - It was suggested that we have an MP3 presentation at the next meeting. - It was suggested that Christoph Leser give a presentation at a future meeting that describes ARMA using some realistic ground vehicle time histories.

ATV Contributions:

At the previous meeting there was some discussion about the need to instrument and measure the loads generated by the operator. These would include the seat, handle bars and foot pegs. Zhengxian Bai will investigate doing this. There was no information available from Zhengxian.

It was discussed that customer correlation is important and has three primary components; 1) road, 2) ballast, 3) driver characteristics. We will recommend that when we eventually publish the ATV project, that using good customer correlated loads input is important.

New Business:

Several items were brought up and discussed.

Presentation topics for future meetings; - Data Validation - what is state-of-the-art - Correlation - what aspects are important? - the model says displacement is x at point a, the test says displacement is y at point a. - Data Characterization - ARMA - MP3 The Division may want to look at taking a leading role in methods/techniques for predicting analytical loads based on previous loads. How might these drive simulation models? Art Page will give a 15-minute presentation on this topic at the next meeting. We also would like a presentation from the modeling side to discuss how this information is used as input. Art said he would also be willing to discuss this at the next meeting.

The meeting was adjourned.

Respectfully submitted by: Christoph Leser - SAE FD&E Road Load Data Division Chairperson

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SAE Fatigue Design and Evaluation Committee

Surface Enhancement Division -Unconfirmed Minutes

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

1) Presentation by Russ Cherenkoff on the Axial Fatigue Performance of Shot Peened 2014-T6 Die Forged Aluminum. A discussion ensued on the use of standard Almen strips for peening aluminum. The potential need for aluminum Almen strips was discussed.

2) Dave Francis presented his computer program of "Simulated Shot Peen Coverage"

3) Dale Lombardo presented his computer program of "Simulated Shot Peen Coverage"

4) Discussion of SAE J2277 Shot Peen Coverage (Dave Francis, sponsor) Jack Champaigne to procure information on replica usage and coverage coupons used in Europe. This was discussed with regard to removal of sections 4.4 and 4.5 of SAE J2277. Otherwise this specification is ready to be sent out for ballot.

5) Dale Lombardo presented a review of software for Almen strip saturation curve plotting. Dale will work with several commercial vendors to develop a SAE standard procedure for use of computer generated saturation curves. (Boeing, British Aerospace, General Electric, Baiker, Progressive Technologies, Metal Improvement Co, and Electronics Incorporated.)

6) Discussion of SAE J442 Jack Champaigne offered the following revisions: a.) Almen strip width was 0.745"-0.750" and will be changed (back) to 0.742"-0.750" b.) Revise the maximum allowable Almen gage indicator tip force from 25 grams to 60 grams.

Surface Enhancement Division consensus approved the changes as suggested.

A discussion by the task group headed by A. Ahmad of the variation in Almen strip performance between various suppliers occurred. Ahmad presented data that suggested slight variation between supplier’s strips. His data was inconclusive and the team agreed to meet to discuss specific experiments to quantify variation between suppliers and identify the causes. Ahmad will convene a meeting of the task group in June or July.

7) Discussion of J2441, Shot Peening (sponsored by D. Hale). Specification to be sent out for ballot.

8) Jack Soules, Cleveland State University, presented his findings on eddy current residual stress measurements. He is able to determine peening intensities non-destructively. An algorithm was being developed to plot residual stress vs. depth profiles.

Respectfully submitted by: Jack Champaigne - SAE FD&E Surface Enhancement Division Chairperson (Minutes recorded by J. Bernabe, Secretary)

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SAE Fatigue Design and Evaluation Committee

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.

Respectfully submitted: Raj Thakkar (Chairperson) and Paul Lubinski (Vice-Chairperson) of the SAE FD&E Component Test Division