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.

4. 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.