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Expired Canadian patentCanada

Modified ring test

CA 1291263 C · Owner: Roegiers, Jean C. · Inventors: Roegiers, Jean C.; Thiercelin, Marc

CIPO record

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Its claims, description and drawings are in the Canadian Patents Database.

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Abstract From the Canadian patent

A novel test specimen configuration and modified ring test method for determining the fracture toughness KIC, using rock core is disclosed. The use of a truncated hollow cylindrical specimen under compressive load avoids the development of a large process zone (microcracked region) during testing, thus allowing accurate fracture toughness measurements on subsized specimens. Results using soft sandstones and Indiana limestone validate the procedure.

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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.

Why it's free to use

  • Granted October 22, 1991. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended October 22, 2008.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledOctober 21, 1987
GrantedOctober 22, 1991
Term endedOctober 22, 2008
Patent numberCA 1291263 C
Classification (IPC)G01N19/08 +2 more

Timeline

Timeline From CIPO dates

1988199119941997200020032006Application filedOct 21, 1987Patent grantedOct 22, 1991Term endedOct 22, 2008

Sources & verification

Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.