Compressive fatigue response of Al-Si10-Mg bionic thin tubes under constant and variable amplitude loading

Abstract

In this study, two different lattice structures are mimicked from the Euplectella aspergillum. These lattice structures are used to design novel bionic tubes. Bionic tubes are fabricated with Al-Si10-Mg material using selective laser melting (SLM) process. The work investigates the thin tubes' dynamic response under cyclic fatigue loading; with constant and variable amplitude. Fatigue stiffness, fatigue life, and fracture mechanism of the bionic thin tubes are compared with honeycomb based thin tubes. The deformation and fracture behavior of the thin tubes under constant and variable amplitude is compared. Results showed that the portion of fatigue life spent in damage initiation and propagation depends on the stress amplitude and design. Also, the fracture mechanism is independent of stress amplitude and depends on fatigue loading and design type. Finite element modelling (FEM) is used to compare the stress distribution in different lattices. Numerical results showed the dependence of stress distribution on the loading and tube type. Overall, when novel bionic tubes are compared with honeycomb based thin tubes, the bionic tubes showed better fatigue performance. The newly designed bionic tubes can be used as grid-stiffened structures and structural applications.