Report of Investigations 9106: An Investigation of Crack Propagation with a Wedge Identer to Improve Rock Fragmentation Efficiency

Details

• Journal Article:
  MISSING
• Personal Author:
  Larson, David A. ; Mades, Joel F. ; Morrell, Roger J.
• Description:
  The Bureau of Mines conducted basic experiments to study the process of crack propagation with a wedge indenter. The work was conducted under plane stress conditions in a hard, brittle limestone. The purpose of these experiments was to first gain an understanding of the basic crack propagation process under a sharp indenter, and second, to determine how the crack propagation process could be used to improve mechanical fragmentation systems. Three methods of rock fracture with the wedge indenter were investigated in this program. These were the confined indentation tests, the unconfined splitting tests, and the edge chipping tests. The confined indention tests represent worse case conditions for crack growth, and formed the lower bound on fracture efficiency. The unconfined splitting tests represented best case conditions and fixed the upper bound of fracture efficiency. The edge chipping tests represented an idealized fragmentation process based exclusively upon the highly efficient fracture propagation process. Edge chipping achieved a specific energy of 25 in.Lbf/in3 compared with conventional drag cutters, which required a specific energy of at least 2,385 in.Lbf/in3. Thus edge chipping is up to 100 times more efficient than conventional drag cutting. Because of these promising results, more work is planned with the fracture propagation process in three dimensions. [Description provided by NIOSH]
• Subjects:
  Mining Occupational Health Safety
• Source:
  MISSING :28 pages
• Series:
  NIOSH Numbered Publications   ; Mining Publications  
• Subseries:
  Report of Investigations
• Document Type:
  Text
• Genre:
  Report
• Place as Subject:
  United States
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  TCRC - Twin Cities Research Center
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  33 pdf pages
• NIOSHTIC Number:
  nn:10005778
• Federal Fiscal Year:
  1987
• Peer Reviewed:
  False
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:8df5e15dd1b641231487ccaf92702eddc6cc2a18b866585b1bd6b53bf048a81501efb04494f1c9b4a871f189ae9c47427eee44976cc7bcfbbce73989af30a976
• Download URL:
  https://stacks.cdc.gov/view/cdc/10310/cdc_10310_DS1.pdf
• File Type:
  [PDF - 12.53 MB ]