Accession Number : ADA318094

Title :   Axial Crack Propagation and Arrest in a Pressurized Fuselage.

Descriptive Note : Final rept.,

Corporate Author : WASHINGTON UNIV SEATTLE DEPT OF MECHANICAL ENGINEERING

Personal Author(s) : Kosai, M. ; Shimamoto, A. ; Kobayashi, A. S.

PDF Url : ADA318094

Report Date : SEP 1996

Pagination or Media Count : 187

Abstract : A hybrid experimental-numerical investigation was undertaken to establish a practical crack kinking criterion in the presence or absence of multiple site damage (MSD) in a pressurized airplane fuselage. Ramulu Kobayashi crack kinking criteria was modified to predict self-similar crack propagation along a line of MSD and subsequent kinking near a tear strap. Instrumented biaxial test specimens and small-scale fuselage rupture experiments were conducted to generate the crack kinking and crack velocity data which was then input to a large deformation, elasto-dynamic, finite element model of the fracture specimen. The computed Mixed-Modes I and II stress intensity factors and a large axial stress preceding the propagating crack were used to evaluate the self-similar crack extension and the crack kinking criterion along the crack trajectory. Excellent agreement was obtained between the predicted and measured crack kinking angles and locations. Additional verification was made through the match between the computed and measured strain gage data. The biaxial specimen tests showed that in spite of the presence of plane strain Mode II stess intensity factor (K11) and the large axial stress ahead of the propagating crack, axial crack extension would continue in the axial direction of the skin is weakened by MSD. The crack propagated through the tear strap in the presence of a continuous MSD and kinked when the MSD terminated at the tear strap. However, if there is a short secondary crack under the tear strap, the lead crack kinked at the long groove end but reconnected to the secondary crack. The small-scale fuselage rupture tests showed that the pre-existing axial through crack along the stringer immediately kinked upon propagation due to the Mixed-Modes I and II state caused by the one-sided opening of the crack flap. The diagonally running crack subsequently turned circ

Descriptors :   *CRACK PROPAGATION, *FUSELAGES, *PRESSURIZATION, *BIAXIAL STRESSES, TEST AND EVALUATION, STRESSES, VELOCITY, MATHEMATICAL MODELS, PROPAGATION, AIRCRAFT, OPENING(PROCESS), AGING(MATERIALS), DAMAGE, VERIFICATION, SECONDARY, FINITE ELEMENT ANALYSIS, DEFORMATION, CRACKS, SITES, NUMERICAL ANALYSIS, INTENSITY, RUPTURE, SHORT RANGE(TIME), CYLINDRICAL BODIES, STRAIN GAGES, INSTRUMENTATION, FLAPS(CONTROL SURFACES), HYBRID SYSTEMS, STRAPS, GROOVING, TRAJECTORIES, TEARING.

Subject Categories : Aircraft
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE