Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY) May 2007 REPORT TYPE SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION/AVAILABILITY STATEMENTApproved for public release; distribution is unlimited. SUPPLEMENTARY NOTES ABSTRACTThe U.S. Army Aviation and Missile Research Development and Engineering Command (AMRDEC), Aviation Engineering Division in Huntsville, AL requested that the U.S. Army Research Laboratory, Weapons and Materials Research Directorate at Aberdeen Proving Ground, MD develop and execute a program aimed at evaluating the shot-peening sensitivity of several aerospace materials. The materials represent the four most common metals utilized on U.S. Army aviation shot-peened components. The study had three main thrusts: to assess the variation in shot-peening intensity expected from various shot-peening parameters, to assess the fatigue strength yielded at prescribed shot-peening intensities, and to correlate surface roughness and x-ray diffraction residual stress analysis data to those prescribed stress intensities. Once the shot-peening parameters' effect on shot-peening intensity was characterized, specific intensities and parameters were selected over an intensity range (dictated by AMRDEC) for each material to assess the sensitivity on fatigue strength.

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number.