Accession Number : AD0267273

Title :   A SUMMARY OF THE THEORY OF FRACTURE IN METALS

Corporate Author : BATTELLE MEMORIAL INST COLUMBUS OHIO DEFENSE METALS INFORMATION CENTER

Personal Author(s) : SPRETNAK,J.W.

Report Date : 07 AUG 1961

Pagination or Media Count : 1

Abstract : The theoretical strength of metals, bas d on atomic forces, is in the order of 100 to 1000 greater than that observed. Reasons for this discrepancy are discussed in detail, but the more important ones are (1) lattice imperfections, (2) the fact th t real metals ar polycrystalline aggregates, (3) crystalline anisotropy, and (4) the ability of metals to deform by shear. Plastic flow, particularly heterogeneous plastic flow, is intimately associated with crack initiation. The precise conditions under which plastic flow c ase and bond rupturing (cracking begins are not completely understood. The body-centered cubic lattice has geometric characteristics that make it particularly susceptible to fracture with little or no preceding plastic flow. Multidirectional stress fields, both microscopic and macroscopic, affect the degree of plastic deformation that precedes crack initiation. The theory of fracture as it exists oday is reviewed. (Author)

Descriptors :   ALLOYS, ALUMINUM, ALUMINUM ALLOYS, ANISOTROPY, BISMUTH, CHLORIDES, CHROMIUM, COPPER, CRYSTAL LATTICES, CRYSTALS, DEFORMATION, FRACTURE (MECHANICS), IRON, IRON ALLOYS, METALS, MOLYBDENUM, PHYSICAL PROPERTIES, PLASTIC PROPERTIES, ROCKET ENGINE CASES, SHEAR STRESSES, SILICON ALLOYS, SINGLE CRYSTALS, SOLID ROCKET PROPELLANTS, SOLIDS, STRONTIUM COMPOUNDS, TELLURIUM, TEMPERATURE, THEORY, THERMODYNAMICS, ZINC, ZINC ALLOYS

Distribution Statement : APPROVED FOR PUBLIC RELEASE