Design of high-performing circular tubes of complex cross-sections guided by a single non-dimensional governing parameter

Abstract

Bio-inspired and hierarchical configurations have been extensively studied to enhance the energy absorption capacity of thin-walled tubes under axial crushing. However, general design guidelines with governing factors remain unclear. Our recent study [Li et al., IJMS 2024] has discovered a single non-dimensional governing parameter ω, which could guide the design of the configuration of high-performing tubes. It was unveiled that the larger the non-dimensional governing parameter ω, the better the performance of tubes under axial crushing. Following the aforementioned study, the present paper strategically proposes a class of circular tubes of complex cross-sections with relatively large magnitudes of ω and investigates them numerically, theoretically and experimentally. Tubes with a reduced diameter of small tubes on ribs without gaps possess larger ω and absorb the most energy among this class of tubes studied. Subsequently, to broaden the application range of theoretical models for the energy absorption of tubes, the effect of solidity ratios is explored. Both configuration (as indicated by ω) and solidity ratio ϕ play dominant roles in the performance of the tubes with complex cross-sections. The expression of effectiveness of energy absorption (EEA) is further expressed as a function of ω and ϕ so that it can be employed to predict the energy absorption characters of tubes with various relative density. The quasi-static axial compressive tests were also conducted and used to validate the numerical and theoretical models as well as the proposed design strategy.