Full field strain measurement during a tensile split Hopkinson bar experiment

A method for full field measurement of strain (and strain rate) during a tensile split Hopkinson bar test is introduced. The measurements are done by using the ARAMIS three-dimensional image correlation system. The system uses two digital high-speed cameras that provide a synchronized stereo view of the specimen. Depending on the number of pixels used, the system is capable of recording frames at a rate of up to 250,000 per second. The results show the complete strain field during the tests, including details of the strain field when necking develops prior to the failure. Before necking, when the deformation is homogeneous, the strains from the ARAMIS system agree with the strain that is determined from the elastic waves that are recorded in the incident and transmitter bars