Accession Number : ADA314506

Title :   Numerical Modeling of Ductile Tearing Effects on Cleavage Fracture Toughness.

Descriptive Note : Technical rept. Jun 92-Nov 93,

Corporate Author : ILLINOIS UNIV AT URBANA DEPT OF CIVIL ENGINEERING

Personal Author(s) : Dodds, R. H., Jr. ; Tang, M. ; Anderson, T. L.

PDF Url : ADA314506

Report Date : JUN 1994

Pagination or Media Count : 43

Abstract : Previous work by the authors described a micromechanics fracture model to correct measured Jc-values for the mechanistic effects of large-scale yielding. This new work extends the model to also include the influence of ductile crack extension prior to cleavage. Ductile crack extensions of 10-15 X the crack-tip opening displacement at initiation are considered in plane-strain, finite element computations. The finite element results demonstrate a significant elevation in crack-tip constraint due to macroscopic sharpening of the extending tip relative to the blunt tip at initiation of growth. However, this effect is offset partially by the additional plastic deformation associated with the increased applied J required to grow the crack. The initial a 1W ratio, tearing modulus, strain hardening exponent and specimen size interact in a complex manner to define the evolving near-tip conditions for cleavage fracture. The paper explores development of the new model, provides necessary graphs and procedures for its application and demonstrates the effects of the model on fracture data sets for two pressure vessel steels (A533B and A515).

Descriptors :   *STEEL, *FRACTURE(MECHANICS), *CRACK PROPAGATION, *DUCTILITY, PLASTIC DEFORMATION, STRESS STRAIN RELATIONS, DATA BASES, MATHEMATICAL MODELS, STRESS ANALYSIS, FINITE ELEMENT ANALYSIS, DISPLACEMENT, MODULUS OF ELASTICITY, STRAIN HARDENING, TOUGHNESS, BRITTLENESS, DUCTILE BRITTLE TRANSITION, PRESSURE VESSELS, PLASTIC PROPERTIES, IRON ALLOYS, YIELD STRENGTH, MICROMECHANICS, TEARING, STRESS CONCENTRATION, TRIAXIAL STRESSES.

Subject Categories : Properties of Metals and Alloys

Distribution Statement : APPROVED FOR PUBLIC RELEASE