VARIATIONS OF STRAIN ENERGY RELEASE RATE WITH PLATE THICKNESS

Analytical model of a through-thickness crack in a statically stretched plate is presented in which the crack front stress state is permitted to vary in the direction of the plate thickness. The amplitude or intensity of this stress field remains essentially constant over a major portion of the interior crack front which is in a state of plane strain while drastic changes are observed in a layer of the plate material close to the free surface. The degree of this change is a function of the plate thickness to crack length ratio. Numerical results are given to illustrate this effect. The average amount of work available for extending a small segment of the crack across the thickness is associated with an energy release rate quantity G in a manner similar to the two-dimensional Griffith crack model. The theoretically calculated G is shown to increase with increasing plate thickness indicating that available work for crack extension is higher in a thicker plate. This result is in agreement with the experimentally observed fracture data in the range of moderately thick plates where the fracture toughness is inversely proportional to the plate thickness. The proposed model is not expected to apply for thin plates where plastic yielding is of primary concern. This effect requires an extended discussion which will be treated in a separate communication.

• Corporate Authors:

  Lehigh University

  Institute of Fracture and Solid Mechanics
  Bethlehem, PA  United States  18015
• Authors:
  • SIH, G C
  • Hartranft, R J
• Publication Date: 1971-10

Media Info

• Features: References;
• Pagination: 30 p.

Subject/Index Terms

• TRT Terms: Cracking; Fracture mechanics; Plastic deformation; Stresses
• Uncontrolled Terms: Crack propagation
• Old TRIS Terms: Crack stresses
• Subject Areas: Marine Transportation; Materials;

Filing Info

• Accession Number: 00032213
• Record Type: Publication
• Source Agency: Ship Structure Committee
• Report/Paper Numbers: IFSM-71-8
• Contract Numbers: NGR-39-007-025
• Files: TRIS
• Created Date: Apr 21 1972 12:00AM