Accession Number : ADP006814

Title :   Damage Progression Under Compressive Loading in Composite Laminates Containing an Open Hole,

Corporate Author : NATIONAL RESEARCH COUNCIL OF CANADA OTTAWA (ONTARIO) INST FOR AEROSPACE RESEA RCH

Personal Author(s) : Poon, C. ; Bellinger, N. C. ; Gould, R. W. ; Raizenne, M. D.

Report Date : APR 1992

Pagination or Media Count : 16

Abstract : This paper describes an experimental investigation into damage progression in compressively loaded quasi-isotropic laminates with a circular hole and the prediction of damage initiation using 3D finite element failure analysis. Notched laminated plates were fabricated from Narmco IM6/5245C with three stacking sequences; +45/0/45/90(sub 6s), ( + 45)sub 3/(0)sub 3/(-45)sub 3/(90)sub 3)(sub 2S), AND ( + 45)6/(O)sub 6/(-45)sub 6/(90)sub 6)sub s. Most specimens were tested to ultimate failure but some were stopped prior to failure. The criterion for stopping the test was the detection of audible acoustic emission. The tests revealed that the notched strength decreased as the ply group thickness increased. An examination of the hole surface of those specimens not taken to ultimate failure revealed delaminations at the +45 deg /C deg and -45 deg/O deg interfaces and failure of the +45 deg and 0 deg ply groups. For the specimen where six plies with the same fibre orientation were grouped, the midplane of the O deg ply group also contained a delamination. A tensor polynomial failure criterion which used all the six stress states determined from the 3D finite element analysis at the laminate characteristic dimension was used to predict initial laminate failure.

Descriptors :   *LAMINATES, *FAILURE(MECHANICS), *MILITARY AIRCRAFT, *FIBER REINFORCED COMPOSITES, ACOUSTIC EMISSIONS, AIRCRAFT, DAMAGE, DELAMINATION, DETECTION, EDGES, FINITE ELEMENT ANALYSIS, INTERFACES, MATERIALS, PLATES, POLYNOMIALS, PREDICTIONS, SEQUENCES, STACKING, STRESSES, SURFACES, TENSORS, TEST AND EVALUATION, THICKNESS, STRESS STRAIN RELATIONS, CARBON FIBERS, POLYMERS, MATRIX MATERIALS, TOUGHNESS, REPRINTS, NATO.

Subject Categories : Laminates and Composite Materials
      Aircraft

Distribution Statement : APPROVED FOR PUBLIC RELEASE