Large Deformation and Energy Absorption Behaviour of Perforated Hollow Sphere Structures under Quasi-Static Compression

Abstract

Hollow sphere structures with perforations (PHSSs) in three different arrangements (simple cubic (SC), body-centred cubic (BCC), and face-centred cubic (FCC)) were fabricated through three-dimensional (3D) printing, and the mechanical behaviours of these PHSSs under quasi-static compression were investigated experimentally and numerically. The results indicated that under uniaxial compression, the PHSSs mainly undergo three stages, i.e., a linear elastic stage, a large deformation or plateau stage, and a densification stage. During the stage of large deformation, the SC and BCC PHSSs experience a preliminary compaction sub-stage after layer-by-layer buckling, while for the FCC PHSS, layer-by-layer collapse and compaction are the dominant deformation behaviours. A numerical simulation was employed to study the mechanical properties of PHSSs with different geometric parameters under quasi-static compression and to explore the effect of the wall thickness, hole diameter, and sphere arrangement on the first peak stress, plateau stress, and specific energy absorption (SEA) of the PHSSs. The results reveal that the geometric parameters have a significant impact on the large deformation behaviour and energy absorption capacity of PHSSs. The presented PHSS is also proven to be much lighter than traditional metallic hollow sphere structure (MHSS) and has higher specific strength and SEA.

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“…were reduced by the rule-of-mixture and the Reuss model [53]. According to the rule-of-mixture and the deformation stages of the unit cells, the strength of the BHC-SHC composite lattice at 𝜀 = 𝜀 2 can be modeled using Equations ( 21)-( 24 𝜀 2 (24) where 𝐸 𝐶𝐻𝐶,𝐹1 , 𝐸 𝐶𝐻𝐶,𝐹2 , and 𝐸 𝐶𝐻𝐶,𝐹2 are the effective moduli of the first, second, and third lattice layers, respectively; 𝐸 𝐵𝐻𝐶,𝜌 𝑚 =132 , 𝐸 𝐵𝐻𝐶,𝜌 𝑚 =212 , 𝐸 𝐵𝐻𝐶,𝜌 𝑚 =282 , 𝐸 𝑆𝐻𝐶,𝜌 𝑚 =180 , 𝐸 𝑆𝐻𝐶,𝜌 𝑚 =320 , and 𝐸 𝑆𝐻𝐶,𝜌 𝑚 =420 are the moduli of the unit cells with different types and densities of the microstructures calculated by Equation ( 9); and 𝜎 𝐵𝐻𝐶−𝑆𝐻𝐶𝛼 is the strength of the first wavy stage for the BHC-SHC composite lattice. Based on Equations ( 18)-( 21), the modulus of each BHC-SHC composite lattice layer was found to be decreased by the moduli of the BHC unit cells, whereas it was estimated by the Reuss model that a further reduction in the lattice strength originated from the tandem connection of the lattice layers.…”

“…Among the different metamaterial structural designs, the spherical hollow structure (SHS) [21,22] exhibits tremendous energy absorption and is lightweight because of the high porosity and highly plastic behavior of its microstructure. To explore the relationship between the energy absorption behavior and the design parameters of SHS materials, their mechanical properties were widely investigated as a function of sphere sizes [23], packing patterns [24], and relative densities [25]. Nevertheless, the SHS structures proposed in [23][24][25] were manufactured with identical hollow spheres and their structure was not optimized to further unlock its true energy absorption potential.…”

“…To explore the relationship between the energy absorption behavior and the design parameters of SHS materials, their mechanical properties were widely investigated as a function of sphere sizes [23], packing patterns [24], and relative densities [25]. Nevertheless, the SHS structures proposed in [23][24][25] were manufactured with identical hollow spheres and their structure was not optimized to further unlock its true energy absorption potential. With an increasing demand of the protective and damageresistance lightweight materials in nowadays aerospace industries, the development of lattice metamaterial with a more significant improvement of their protective energy absorption performance is desired [26].…”