Innovative Methodologies to Determine Remaining Fatigue Life of Aircraft Dynamic Components Navy SBIR FY2006.1 Sol No.: Navy SBIR FY2006.1 Topic No.: N06-020 Topic Title: Innovative Methodologies to Determine Remaining Fatigue Life of Aircraft Dynamic Components Proposal No.: N061-020-0006 Firm: Direct Measurements Inc. 1414 Epping Forest Dr Atlanta, Georgia 30319-2539 Contact: William Ranson Phone: (803) 530-9470 Web Site: www.directmeasure.com Abstract: Direct Measurememts Inc. will use its proprietary optical strain measurement technology to measure plastic strain in cyclically stressed coupons as a metric to predict crack iniation. The literature supports this approach. Heretofore to the DMI nt technology there has not been an effective way to measure plastic strain in an operational system. Lemaitre presents the case for plastic strain as a metric for predicting crack initiation in A COURSE ON DAMAGE MECHANICS , 2nd Edition, Springer ,1996. The book states: " L. M. Kachanov published in 1958 a simple model of material damage which subsequently could be extended to brittle elastic, plastic or viscous materials under all conditions of uniaxial or multiaxial, simple or cyclic loadings, so that it may be considered nearly universal". Thus, theory has advanced to practical application status as opposed to an earlier statistical modeling of the damage phenomenon. Lemaitre and recent works support using plastic strain as a predictor of crack initiation ( see: Finite Element Modeling of Fatigue Damage Using a Continuum Damage Mechanics Approach, by. De Jesus et al., pages 157-164, Journal of Pressure Vessel Technology, May 2005 Vol. 127.) ASTM E-606-92 and ASTM E 1049-85 are proposed for the testing procedures . Benefits: Benefits: Save lives and prevent injuries by antucpating potential catastrophic in flight failure of an aircrfat by periodic measuremnt of accumaulted damage in critical parts and linking the accumulated damge to failure of the part,maintaining the maximum number of mission ready aircraft through supply chain optimization, reduce inventoires and reduce inventoires of obsolete parts. Return