Research scientist, Ontario Research Foundation, Sheridan Park Research Community, Mississauga, Ontario
Manager, Metals Technology Centre, Ontario Research Foundation, Sheridan Park Research Community, Mississauga, Ontario
Instrumented impact testing should be a basic component of fracture resistance evaluation. However, the output signals from an instrumented tup can be difficult to interpret unless precautions are taken to minimize spurious signals generated by extraneous effects. Instrumented drop-weight tear testing (DWTT) was used to study the fracture behavior of G40.21-44T construction grade steel. The fracture process was monitored in detail by means of high-speed photography at 6000 frames per second, and correlated with the output traces from the Dynatup 8000 impact testing machine. The traces were analyzed with reference to the dynamic response characteristics of the machine/specimen system and compared with the output traces derived from instrumented specimens. The results of visual observation of the fracture process together with the output traces of load and strain-transducers provide strong evidence that the peak load coincides with crack initiation in this steel. The spurious signals are related primarily to the mechanical characteristics of the testing machine and to specimen oscillations.
Paper ID: JTE10776J