The development of precise data for the effect of chemistry and processing variables on the fracture toughness of low to medium carbon cast steels, is paramount to an increased understanding of the fracture behaviour of these important engineering materials. This knowledge would, in itself, lead to improvements in alloy development/selection rationale and increased cast steel usage, particularly in critical areas. / Toward this end, an investigation into the influence of Cr, Mn and Ni additions on the room temperature fracture toughness and flow properties of 0.30, 0.40 and 0.55 wt% C cast alloys was conducted. In order to avoid the chemical and processing complexity normally associated with commercial castings, the study was undertaken on heavy section castings produced in the laboratory from melts composed of commercial purity ingredients. Measurements were conducted on three-point bend test pieces machined from heat-treated castings. The fracture toughness techniques used included LEFM (K(,IC)), J integral and COD ((delta)(,c)). A potential drop method was employed to record crack initiation. / Very high room temperature fracture toughnesses were achieved in the majority of the alloys examined, with only three alloys having K(,IC) values of less than 150 MN.m('-3/2) or COD, (delta)(,c), values of less than 0.1 mm. Further, yield stress ((sigma)(,ys)) values were found to lie within 80-105% of those recorded for commercial castings of comparative composition. / At the 0.30 and 0.40 wt% C levels it was found that the room temperature fracture toughness of the alloys was relatively independent of the microstructure as well as the amount and particular addition element employed, although variations in the tensile properties were noted. / At the 0.55 wt% C level significant differences in the fracture behaviour were caused by the individual element additions. Manganese was found to improve the toughness of the high carbon alloys, while nickel produced little change and chromium had a negative effect on toughness. In each case the influence of these elements was manifested in microstructural differences. / The results of this study are reviewed in the light of the limited data available from commercial cast steels and the need for improved toughness performance without undue loss of yield strength and other properties. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of author.) UMI

Thesis (M.S.)--George Mason University, 2009. / Vita: p. 64. Thesis director: Rainald Löhner. Submitted in partial fulfillment of the requirements for the degree of Master of Science in Computational Sciences. Title from PDF t.p. (viewed June 10, 2009). Includes bibliographical references (p. 60-63). Also issued in print.

No description available.

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

No description available.

No description available.

Trans-scaphoid, trans-radial styloid, trans-triquetral perilunate fracture dislocations are rare. We describe a 19-year-old male who suffered this injury after crashing his bicycle. He underwent open reduction internal fixation and percutaneous pinning. Scaphoid union was achieved at 8 weeks. Near complete range of painless motion was achieved by 4 months.

This thesis presents research toward the development of a simple inexpensive fracture toughness tool for polymeric materials. Experiments were conducted to test the specimen configuration and the fracture toughness tool against an established ASTM standard for polymer fracture toughness, D5045, and a commonly used four-point bend method. The materials used in this study were polycarbonate and high density polyethylene. Reductions in both the production time and the variability resulting from the preparation of the specimens were addressed through the use of specially designed fixtures. The effects from the razor cut depths used in the chevron notch were compared to the fracture toughness values obtained in order to determine the effect upon the validity of the fracture toughness.

Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Bibliography: leaves 204-211. / by Thomas Dale Ketcham. / Sc.D.