Identifying the stress-strain curve of materials by microimpact testing. Application on pure copper, pure iron, and aluminum alloy 6061-T651

The mechanical response of materials under repeated impact loading is of primary importance to model different types of surface mechanical treatments, such as shot peening. A reverse identification method of stress-strain curves using repeated impact has been developed by Kermouche et al. [Kermouche et al., Mater. Sci. Eng., A 569, 71-77 (2013)] and later improved by Al Baida et al. [Al Baida et al., Mech. Mater. 86, 11-20 (2015)]. This study deals with the experimental validation of this method on three materials: a home-made pure iron, a commercially pure copper, and an industrial aluminum alloy. An approximate method derived from cone indentation theory to check the reverse method reliability. Balls of different sizes have been used to cover a wide enough range of strain. The results are also compared with macroscopic compression and traction tests. The effect of the strain rate on the stress-strain curve is discussed. The conclusion section highlights the rapidity and the ease of use of the reverse identification method.