NASA TECHNICAL NOTE CM I NASA TN D-2599 Reproduced From Best Available Copy DISTRIBUTION STATEMENT A Approved for Public Release Distribution Unlimited *> 8 6' 4 > FRACTURE TOUGHNESS TESTING by John E. Srawley and William F Brown, Jr. Lewis Research Center Cleveland, Ohio 70010920 198 NATIONAL AERONAUTICS AND SPACE ADMINISTRATION • WASHINGTON, D. C. • JANUARY 1965