Apparatus for Accelerating Measurements of Environmentally Assisted Fatigue Crack Growth at Low Frequency


  • Contribution of the National Institute of Standards and Technology, an agency of the US government; not subject to copyright in the USA


Testing the fatigue crack growth of materials at low frequencies and realistic stress intensity factors has historically demanded a large investment in time. Running a test at a frequency less than 1 Hz can take weeks, and if meaningful statistics are needed, 2–3 months might be necessary to provide one set of data on the fatigue crack growth rate (FCGR). A means of reducing that time frame by testing as many as 10 specimens simultaneously is presented. With this innovative design, compact tension specimens are run in series and according to ASTM Standard E647. Furthermore, there is no need to interrupt the fatigue testing of the linked specimens should one or more finish before the others. Specimens tested in this fashion generate consistent data of FCGR.