Dynamic impact testing of cellular solids and lattice structures: Application of two-sided direct impact Hopkinson bar

0534057 - ÚTAM 2022 RIV SE eng J - Journal Article
Fíla, T. - Koudelka_ml., P. - Falta, J. - Zlámal, P. - Rada, Václav - Adorna, M. - Bronder, S. - Jiroušek, O.
Dynamic impact testing of cellular solids and lattice structures: Application of two-sided direct impact Hopkinson bar.
International Journal of Impact Engineering. Roč. 148, February (2021), č. článku 103767. ISSN 0734-743X. E-ISSN 1879-3509
R&D Projects: GA MŠMT(CZ) EF16_019/0000766
Institutional support: RVO:68378297
Keywords : direct impact Hopkinson bar * cellular solids * auxetic metamaterials * digital image correlation * wave separation
OECD category: Materials engineering
Impact factor: 4.592, year: 2021
Method of publishing: Open access
https://doi.org/10.1016/j.ijimpeng.2020.103767

Direct impact testing with a Hopkinson bar is, nowadays, a very popular experimental technique for investigating the behavior of cellular materials, e.g., lattice metamaterials, at high strain-rates as it overcomes several limitations of the conventional Split Hopkinson Pressure Bar (SHPB). However, standard direct impact Hopkinson bars (DIHB) have only single-sided instrumentation complicating the analysis. In this paper, a DIHB apparatus instrumented with conventional straingauges on both bars (a so called Open Hopkinson Pressure Bar - OHPB) was used for dynamic impact experiments of cellular materials. Digital image correlation (DIC) is used as a tool for investigating the displacements and velocities at the faces of the bars. A straight-forward wave separation technique combining the data from the strain-gauges with the DIC is adopted to increase the experiment time window multiple times. The experimental method was successfully tested at impact velocities in a range of 5 − 30m · s−1 with both linear elastic and viscoelastic bars of a medium diameter. It is shown that, under certain circumstances, a simple linear elastic model is sufficient for the evaluation of the measurements with the visco-elastic bars, while no additional attenuation and phase-shift corrections are necessary. The applicability of the experimental method is demonstrated on various experiments with conventional metal foams, hybrid foams, and additively manufactured auxetic lattices subjected to dynamic compression.
Permanent Link: http://hdl.handle.net/11104/0318761