PLASTIC FLOW IN THE LOCALE ON NOTCHES AND CRACKS IN FE-3SI STEEL UNDER CONDITIONS APPROACHING PLANE STRAIN

The development of the plastic zones generated by sharp through-cracks and blunter notches was studied systematically in plates of Fe-3Si steel. A sensitive etching technique revealed the plastic zone both on the plate surface and on parallel and normal interior sections. In addition, the progress of through-the-thickness deformation was followed by monitoring normal displacements at the plate surface. The work encompasses applied stress-crack length-thickness combinations in the range 0.2 is less than the absolute value of (K/Y) squared times 1/t is less than 2 (K is the stress intensity parameter, Y is the yield stress, and t is the plate thickness), with special emphasis on situations where the plastic zone is small relative to the plate thickness and a plane strain state is approached. Three kinds of relaxations are revealed: one in the plane of the plate and two accommodating through-the-thickness deformation. The latter become the dominant mode when the absolute value of (K/Y) squared time 1/t is more than 1.7 or rho is more than t/2 (rho is the zone length). Comparisons with available theoretical treatments show that the calculations of Bilby and Swinden, Tuba, and Rice and Rosengren are in accord with measured zone lengths, but none of the treatments examined provides a satisfactory description of the zone shape. The experiments also provide insights to the level of strain within the zone, and suggest that the absolute value of K/Y, 1/t equals 1 or rho equals t/4 may be a useful upper bound for the plane strain regime.

• Corporate Authors:

  Battelle Memorial Institute

  Long Beach Ocean-Engineering Facility
  Long Beach, CA  United States 
• Authors:
  • Hahn, G T
  • Rosenfield, A R
• Publication Date: 1968-11

Media Info

• Features: References;
• Pagination: 53 p.

Subject/Index Terms

• TRT Terms: Cracking; Fracture properties; Notching (Cutting); Plastic deformation; Strength of materials; Structural analysis
• Identifier Terms: Ship Structure Committee
• Uncontrolled Terms: Crack propagation
• Old TRIS Terms: Notch toughness; Plane strain fracture toughness test
• Subject Areas: Marine Transportation; Materials;

Filing Info

• Accession Number: 00164219
• Record Type: Publication
• Source Agency: Ship Structure Committee
• Report/Paper Numbers: SSC-191
• Contract Numbers: NObs-92383
• Files: TRIS
• Created Date: Oct 29 1977 12:00AM