Dynamic Strain Measurement of Welded Tensile Specimens Using Digital Image Correlation

Abstract

The high strain rate behavior of a welded interface was evaluated using a direct tension Kolsky (Hopkinson) bar setup. The weld and the Heat Affected Zone (HAZ) were included in the gage section of the tensile specimen to evaluate the effects of structural constraint (vs. weld metal only). The welds of interest are under-matched Metal Inert Gas (MIG) butt welds between identical aluminum alloys. Limitations on specimen geometry and maintaining the weld bead intact were imposed to provide a specimen that was most representative of the material and application. Strain determination for the welded specimen with non-uniform cross section was challenging using traditional techniques. A Digital Image Correlation (DIC) system was employed for dynamic strain measurement during high strain rate tensile testing. The results obtained with the DIC system are compared with strain gage data and post-test deformation measurements. Numerical simulations were also employed to aid with interpretation. These will be presented in further detail at the conference.