Origami-inspired honeycombs as energy absorbing materials

Abstract

This thesis proposed a type of origami-inspired honeycombs for energy absorption. The major findings of this thesis were as follows. First, a novel design of origami-inspired honeycomb with self-locking and stiffness gradient was proposed. The design used the concept of Miura-ori pattern to create the unique Miura-ori honeycomb, with a core layer being at the middle sandwiched by two secondary flange layers. The self-locking feature realized by the prior densification of the flanges increased the overall energy absorption whilst keeping the peak load low. It was found that properly designed honeycombs could reduce the peak force by more than 50% and meanwhile possess good specific energy absorption (SEA) in comparison with conventional square honeycomb. Second, derivative Miura-ori-based honeycomb cores were used to create a family of hybrid origami honeycombs. Experimental and numerical results were presented to study the energy absorption capacity of the hybrid honeycombs. It was found that the hybridization could notably affect the peak load and SEA when compared to the individual cores that was constructed in the same form. Especially, it was seen that the hybridization built in a weak-strong-weak manner could reduce the peak force and meanwhile increase the energy absorption efficiency. Third, the effects of dynamic loading on origami honeycombs were investigated numerically. The mechanical behaviors of derivative Miura-ori-based honeycombs, including the hybrid origami-honeycombs were studied under different compressive loading conditions. It was found that under dynamic loading condition, the hybrid origami-honeycomb with stiffness gradient in weak-strong-weak order could noticeably reduce the impact and transmitted force, and increase the energy absorption efficiency at the same time. In conclusion, this thesis presented new paths for creating programmable energy absorbing materials with controllable mechanical properties.