Quasi-static and low-velocity impact behavior of the bio-inspired hybrid Al/GFRP sandwich tube with hierarchical core: Experimental and numerical investigation

Sandwich tube structures bio-mimicking horsetail and human tendons offered significant improvement over traditional single and multi-cell tubular energy absorbers. The present research aims to investigate three manufactured hybrid multi-cell aluminum and GFRP sandwich tubes subjected to quasi-static and low-velocity axial compression. The crashworthiness characteristics and axial crushing failure mechanisms of sandwich tubes are discussed and compared with the quasi-static axial behavior of single Al and GFRP tubes. Further investigations, based on the validation of an FE model versus experimental results, using the commercial finite element code LSDYNA, on the effects of material permutation and inner tubes diameter are perceived through the full-factorial approach of FE parametric study. The quasi-static results revealed that, packing the Al and GFRP tubes in the form of multi-cell sandwich tube generally improves the crushing patterns of individual hollow tubes. Moreover, the low-velocity response of the hybrid multi-cell sandwich tubes showed that the crushing response of the GFRP components despite AL ones depends significantly on the strain rate, where Al tubes undergo irregular diamond deformation. Eventually the results of bio-inspired hybrid multi-cell sandwich tubes indicate that incorporating more GFRP tubes provided an optimal crashworthy design and conduce to a broad range of applications within aerospace, transportation.