NASA-CR-194129 ,-,4 0 0 _ ,.,,4 I ,-- e_ 0 _ C _._0 ,_ 00.c •,.J 0 • U 0 I- _'_ _0 _w- C kAJ .. OwZ O" LAJ_ 0 I O0 O_ kAJ _._ O0 _ ._ O_ _ 0 _-_ v U_ t_ Z ,.-_ 0 ELASTIC PLASTIC FRACTURE MECHANICS METHODOLOGY FOR SURFACE CRACKS SECOND SEMIANNUAL REPORT CONTRACT MSFC CONTROL NO. 91-78 NASA MARSHALL SPACE FLIGHT CENTER HUNTSVILLE, AL 35812 / Project Monitor: Mr. Wayne Gregg Principal Investigator: Dr. Hugo A. Ernst Associate Professor Researchers: D. W. Boatwright W. J. Curtin D. M. Lambert . GEORGIA INSTITUTE OF TECHNOLOGY THE GEORGE W. WOODRUFF SCHOOL OF MECHANICAL Atlanta, GA 30332-0405 ENGINEERING August 1993