Deformation and failure modes of Ti-6Al-4V lattice-walled tubes under uniaxial compression

The compressive large deformation response of tubes, comprising walls made of rhombic dodecahedron unit cells, under quasi-static and dynamic loadings is investigated. Six types of tubes with cellular walls that vary with respect to cell density, tube cross-section and cellular tube wall thickness are manufactured by selective laser melting (SLM). The quasi-static and dynamic compression tests are conducted by using a universal testing machine, a drop hammer device and direct-impact Hopkinson pressure bar (DHPB), respectively, to determine the force-deformation responses of the different structures. In addition, the deformation modes and energy absorption capacity of the tubes are identified. The influence of the cross-sectional shape and cellular-walled density gradient on the energy absorption capacity of the various tube configurations is examined. The results indicate that the Ti-6Al-4V lattice-walled tubes with a density gradient exhibit the best absorption efficiency among the tubes studied. The collapse strength of the square cross section tube tested is more significant than that of its cylindrical counterparts.