Senior research officer, Imperial College of Science, London,
Team leader, Structural Integrity, British Railways Board, Derby,
Pages: 19 Published: Jan 1992
A simple, reliable, and repeatable method has been developed for determining dynamic plane-strain fracture toughness using an on-specimen strain gage. This extends the range of the British Standard Method for Determination of the Dynamic Fracture Toughness of Metallic Materials (BS 6729) to include measurement at impact testing rates. Dynamic finite element computing was used to optimize the position of the gage on the specimen. In tests at low loading rates on Charpy specimens, good agreement was found between toughness values calculated from the applied load and the calibrated gage, and with those measured by the shadow optic caustic technique. At higher rates, several gage types and two adhesives were compared. A satisfactory method was developed for performing tests at high and low temperatures. The technique was applied to larger bend specimens of two steels, and a test program was conducted at seven laboratories to assess the influence of testing machine and instrumentation variables. From the results, a standard calibration and test procedure has been developed.
dynamic fracture toughness, fracture testing standards, impact testing, dynamic testing, fracture (metals)
Paper ID: STP15523S